IP Multicast Routing Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches)
Configuring IGMP
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Configuring IGMP

Contents

Configuring IGMP

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http:/​/​www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Restrictions for Configuring IGMP

The following are the restrictions for configuring IGMP:

  • The device supports IGMP Versions 1, 2 , and 3.

    Note


    For IGMP Version 3, only IGMP Version 3 BISS (Basic IGMPv3 Snooping Support) is supported.


  • IGMP Version 3 uses new membership report messages that might not be correctly recognized by older IGMP snooping devices.
  • IGMP filtering and throttling is not supported under the WLAN.
  • You cannot have a device stack containing a mix of Catalyst 3850 and Catalyst 3650 devices.

Information About IGMP

Internet Group Management Protocol (IGMP) is used to dynamically register individual hosts in a multicast group on a particular LAN. Enabling PIM on an interface also enables IGMP. IGMP provides a means to automatically control and limit the flow of multicast traffic throughout your network with the use of special multicast queriers and hosts.

To participate in IP multicasting, multicast hosts, routers, and multilayer devices must have the Internet Group Management Protocol (IGMP) operating. This protocol defines the querier and host roles:

  • A querier is a network device that sends query messages to discover which network devices are members of a given multicast group.
  • A host is a receiver that sends report messages (in response to query messages) to inform a querier of a host membership.

Hosts identify group memberships by sending IGMP messages to their local multicast device. Under IGMP, devices listen to IGMP messages and periodically send out queries to discover which groups are active or inactive on a particular subnet.

A set of queriers and hosts that receive multicast data streams from the same source is called a multicast group. Queriers and hosts use IGMP messages to join and leave multicast groups.

Any host, regardless of whether it is a member of a group, can send to a group. However, only the members of a group receive the message. Membership in a multicast group is dynamic; hosts can join and leave at any time. There is no restriction on the location or number of members in a multicast group. A host can be a member of more than one multicast group at a time. How active a multicast group is and what members it has can vary from group to group and from time to time. A multicast group can be active for a long time, or it can be very short-lived. Membership in a group can constantly change.

IP Multicast Group Addresses

IP multicast traffic uses group addresses, which are class D addresses. The high-order bits of a Class D address are 1110. Therefore, host group addresses can be in the range 224.0.0.0 through 239.255.255.255. Multicast addresses in the range 224.0.0.0 to 224.0.0.255 are reserved for use by routing protocols and other network control traffic. The address 224.0.0.0 is guaranteed not to be assigned to any group.

IGMP packets are sent using these IP multicast group addresses:

  • IGMP general queries are destined to the address 224.0.0.1 (all systems on a subnet).
  • IGMP group-specific queries are destined to the group IP address for which the device is querying.
  • IGMP group membership reports are destined to the group IP address for which the device is reporting.
  • IGMP Version 2 (IGMPv2) leave messages are destined to the address 224.0.0.2 (all multicast routers on a subnet). In some old host IP stacks, leave messages might be destined to the group IP address rather than to the all-routers address.

IGMP Versions

The device supports IGMP version 1, IGMP version 2, and IGMP version 3. These versions are interoperable on the device. For example, if IGMP snooping is enabled and the querier's version is IGMPv2, and the device receives an IGMPv3 report from a host, then the device can forward the IGMPv3 report to the multicast router.

IGMP Version 1

IGMP version 1 (IGMPv1) primarily uses a query-response model that enables the multicast router and multilayer device to find which multicast groups are active (have one or more hosts interested in a multicast group) on the local subnet. IGMPv1 has other processes that enable a host to join and leave a multicast group. For more information, see RFC 1112.

IGMP Version 2

IGMPv2 extends IGMP functionality by providing such features as the IGMP leave process to reduce leave latency, group-specific queries, and an explicit maximum query response time. IGMPv2 also adds the capability for routers to elect the IGMP querier without depending on the multicast protocol to perform this task. For more information, see RFC 2236.


Note


IGMP version 2 is the default version for the device.


IGMP Version 3

The device supports IGMP version 3. The following are considerations for the device and IGMP version 3:

  • An IGMPv3 device supports Basic IGMPv3 Snooping Support (BISS), which includes support for the snooping features on IGMPv1 and IGMPv2 switches and for IGMPv3 membership report messages. BISS constrains the flooding of multicast traffic when your network includes IGMPv3 hosts. It constrains traffic to approximately the same set of ports as the IGMP snooping feature on IGMPv2 or IGMPv1 hosts.
  • The device supports IGMPv3 snooping based only on the destination multicast IP address. It does not support snooping based on a source IP address or proxy report.
  • IGMPv3 join and leave messages are not supported on devices running IGMP filtering or Multicast VLAN registration (MVR).
  • An IGMPv3 device can receive messages from and forward messages to a device running the Source Specific Multicast (SSM) feature.

IGMP Version Differences

There are three versions of IGMP, as defined by Request for Comments (RFC) documents of the Internet Engineering Task Force (IETF). IGMPv2 improves over IGMPv1 by adding the ability for a host to signal desire to leave a multicast group and IGMPv3 improves over IGMPv2 mainly by adding the ability to listen to multicast originating from a set of source IP addresses only.

Table 1 IGMP Versions

IGMP Version

Description

IGMPv1

Provides the basic query-response mechanism that allows the multicast device to determine which multicast groups are active and other processes that enable hosts to join and leave a multicast group. RFC 1112 defines the IGMPv1 host extensions for IP multicasting.

IGMPv2

Extends IGMP, allowing such capabilities as the IGMP leave process, group-specific queries, and an explicit maximum response time field. IGMPv2 also adds the capability for devices to elect the IGMP querier without dependence on the multicast protocol to perform this task. RFC 2236 defines IGMPv2.

IGMPv3

Provides for source filtering, which enables a multicast receiver host to signal to a device which groups it wants to receive multicast traffic from, and from which sources this traffic is expected. In addition, IGMPv3 supports the link local address 224.0.0.22, which is the destination IP address for IGMPv3 membership reports; all IGMPv3-capable multicast devices must listen to this address. RFC 3376 defines IGMPv3.


Note


By default, enabling a PIM on an interface enables IGMPv2 on that device. IGMPv2 was designed to be as backward compatible with IGMPv1 as possible. To accomplish this backward compatibility, RFC 2236 defined special interoperability rules. If your network contains legacy IGMPv1 hosts, you should be familiar with these operability rules. For more information about IGMPv1 and IGMPv2 interoperability, see RFC 2236, Internet Group Management Protocol, Version 2 .


Devices That Run IGMPv1

IGMPv1 devices send IGMP queries to the “all-hosts” multicast address of 224.0.0.1 to solicit multicast groups with active multicast receivers. The multicast receivers also can send IGMP reports to the device to notify it that they are interested in receiving a particular multicast stream. Hosts can send the report asynchronously or in response to the IGMP queries sent by the device. If more than one multicast receiver exists for the same multicast group, only one of these hosts sends an IGMP report message; the other hosts suppress their report messages.

In IGMPv1, there is no election of an IGMP querier. If more than one device on the segment exists, all the devices send periodic IGMP queries. IGMPv1 has no special mechanism by which the hosts can leave the group. If the hosts are no longer interested in receiving multicast packets for a particular group, they simply do not reply to the IGMP query packets sent from the device. The device continues sending query packets. If the device does not hear a response in three IGMP queries, the group times out and the device stops sending multicast packets on the segment for the group. If the host later wants to receive multicast packets after the timeout period, the host simply sends a new IGMP join to the device, and the device begins to forward the multicast packet again.

If there are multiple devices on a LAN, a designated router (DR) must be elected to avoid duplicating multicast traffic for connected hosts. PIM devices follow an election process to select a DR. The PIM device with the highest IP address becomes the DR.

The DR is responsible for the following tasks:

  • Sending PIM register and PIM Join and Prune messages toward the rendezvous point (RP) to inform it about host group membership.
  • Sending IGMP host-query messages.
  • Sending host-query messages by default every 60 seconds in order to keep the IGMP overhead on hosts and networks very low.
Devices That Run IGMPv2

IGMPv2 improves the query messaging capabilities of IGMPv1.

The query and membership report messages in IGMPv2 are identical to the IGMPv1 messages with two exceptions:

  • IGMPv2 query messages are broken into two categories: general queries (identical to IGMPv1 queries) and group-specific queries.
  • IGMPv1 membership reports and IGMPv2 membership reports have different IGMP type codes.

IGMPv2 also enhances IGMP by providing support for the following capabilities:

  • Querier election process--Provides the capability for IGMPv2 devices to elect the IGMP querier without having to rely on the multicast routing protocol to perform the process.
  • Maximum Response Time field--A new field in query messages permits the IGMP querier to specify the maximum query-response time. This field permits the tuning of the query-response process to control response burstiness and to fine-tune leave latencies.
  • Group-Specific Query messages--Permits the IGMP querier to perform the query operation on a specific group instead of all groups.
  • Leave-Group messages--Provides hosts with a method of notifying devices on the network that they wish to leave the group.

Unlike IGMPv1, in which the DR and the IGMP querier are typically the same device, in IGMPv2 the two functions are decoupled. The DR and the IGMP querier are selected based on different criteria and may be different devices on the same subnet. The DR is the device with the highest IP address on the subnet, whereas the IGMP querier is the device with the lowest IP address.

Query messages are used to elect the IGMP querier as follows:

  1. When IGMPv2 devices start, they each multicast a general query message to the all-systems group address of 224.0.0.1 with their interface address in the source IP address field of the message.
  2. When an IGMPv2 device receives a general query message, the device compares the source IP address in the message with its own interface address. The device with the lowest IP address on the subnet is elected the IGMP querier.
  3. All devices (excluding the querier) start the query timer, which is reset whenever a general query message is received from the IGMP querier. If the query timer expires, it is assumed that the IGMP querier has gone down, and the election process is performed again to elect a new IGMP querier.

By default, the timer is two times the query interval.

Devices Running IGMPv3

IGMPv3 adds support for source filtering, which enables a multicast receiver host to signal to a device which groups it wants to receive multicast traffic from, and from which sources this traffic is expected. This membership information enables the software to forward traffic only from those sources from which receivers requested the traffic.

IGMPv3 supports applications that explicitly signal sources from which they want to receive traffic. With IGMPv3, receivers signal membership to a multicast group in the following two modes:

  • INCLUDE mode--In this mode, the receiver announces membership to a group and provides a list of IP addresses (the INCLUDE list) from which it wants to receive traffic.
  • EXCLUDE mode--In this mode, the receiver announces membership to a group and provides a list of IP addresses (the EXCLUDE list) from which it does not want to receive traffic. In other words, the host wants to receive traffic only from sources whose IP addresses are not listed in the EXCLUDE list. To receive traffic from all sources, like in the case of the Internet Standard Multicast (ISM) service model, a host expresses EXCLUDE mode membership with an empty EXCLUDE list.

IGMPv3 is the industry-designated standard protocol for hosts to signal channel subscriptions in an SSM network environment. For SSM to rely on IGMPv3, IGMPv3 must be available in the network stack portion of the operating systems running on the last hop devices and hosts and be used by the applications running on those hosts.

In IGMPv3, hosts send their membership reports to 224.0.0.22; all IGMPv3 devices, therefore, must listen to this address. Hosts, however, do not listen or respond to 224.0.0.22; they only send their reports to that address. In addition, in IGMPv3, there is no membership report suppression because IGMPv3 hosts do not listen to the reports sent by other hosts. Therefore, when a general query is sent out, all hosts on the wire respond.

IGMPv3 Host Signalling

In IGMPv3, hosts signal membership to last hop routers of multicast groups. Hosts can signal group membership with filtering capabilities with respect to sources. A host can either signal that it wants to receive traffic from all sources sending to a group except for some specific sources (called exclude mode), or that it wants to receive traffic only from some specific sources sending to the group (called include mode).

IGMPv3 can operate with both Internet Standard Multicast (ISM) and Source Specific Multicast (SSM). In ISM, both exclude and include mode reports are applicable. In SSM, only include mode reports are accepted by the last-hop router. Exclude mode reports are ignored.

IGMP Join and Leave Process

IGMP Join Process

When a host wants to join a multicast group, the host sends one or more unsolicited membership reports for the multicast group it wants to join. The IGMP join process is the same for IGMPv1 and IGMPv2 hosts.

In IGMPv3, the join process for hosts proceeds as follows:

  • When a hosts wants to join a group, it sends an IGMPv3 membership report to 224.0.0.22 with an empty EXCLUDE list.
  • When a host wants to join a specific channel, it sends an IGMPv3 membership report to 224.0.0.22 with the address of the specific source included in the INCLUDE list.
  • When a host wants to join a group excluding particular sources, it sends an IGMPv3 membership report to 224.0.0.22 excluding those sources in the EXCLUDE list.

Note


If some IGMPv3 hosts on a LAN wish to exclude a source and others wish to include the source, then the device will send traffic for the source on the LAN (that is, inclusion trumps exclusion in this situation).


IGMP Leave Process

The method that hosts use to leave a group varies depending on the version of IGMP in operation.

IGMPv1 Leave Process

There is no leave-group message in IGMPv1 to notify the devices on the subnet that a host no longer wants to receive the multicast traffic from a specific group. The host simply stops processing traffic for the multicast group and ceases responding to IGMP queries with IGMP membership reports for the group. As a result, the only way IGMPv1 devices know that there are no longer any active receivers for a particular multicast group on a subnet is when the devices stop receiving membership reports. To facilitate this process, IGMPv1 devices associate a countdown timer with an IGMP group on a subnet. When a membership report is received for the group on the subnet, the timer is reset. For IGMPv1 devices, this timeout interval is typically three times the query interval (3 minutes). This timeout interval means that the device may continue to forward multicast traffic onto the subnet for up to 3 minutes after all hosts have left the multicast group.

IGMPv2 Leave Process

IGMPv2 incorporates a leave-group message that provides the means for a host to indicate that it wishes to stop receiving multicast traffic for a specific group. When an IGMPv2 host leaves a multicast group, if it was the last host to respond to a query with a membership report for that group, it sends a leave-group message to the all-devices multicast group (224.0.0.2).

IGMPv3 Leave Process

IGMPv3 enhances the leave process by introducing the capability for a host to stop receiving traffic from a particular group, source, or channel in IGMP by including or excluding sources, groups, or channels in IGMPv3 membership reports.

IGMP Snooping

Layer 2 devices can use IGMP snooping to constrain the flooding of multicast traffic by dynamically configuring Layer 2 interfaces so that multicast traffic is forwarded to only those interfaces associated with IP multicast devices. As the name implies, IGMP snooping requires the LAN device to snoop on the IGMP transmissions between the host and the router and to keep track of multicast groups and member ports. When the device receives an IGMP report from a host for a particular multicast group, the device adds the host port number to the forwarding table entry; when it receives an IGMP Leave Group message from a host, it removes the host port from the table entry. It also periodically deletes entries if it does not receive IGMP membership reports from the multicast clients.


Note


For more information on IP multicast and IGMP, see RFC 1112 and RFC 2236.


The multicast router (which could be a device with the IP services feature set on the active device) sends out periodic general queries to all VLANs. All hosts interested in this multicast traffic send join requests and are added to the forwarding table entry. The device creates one entry per VLAN in the IGMP snooping IP multicast forwarding table for each group from which it receives an IGMP join request.

The device supports IP multicast group-based bridging, instead of MAC-addressed based groups. With multicast MAC address-based groups, if an IP address being configured translates (aliases) to a previously configured MAC address or to any reserved multicast MAC addresses (in the range 224.0.0.xxx), the command fails. Because the device uses IP multicast groups, there are no address aliasing issues.

The IP multicast groups learned through IGMP snooping are dynamic. However, you can statically configure multicast groups by using the ip igmp snooping vlan vlan-id static ip_address interface interface-id global configuration command. If you specify group membership for a multicast group address statically, your setting supersedes any automatic manipulation by IGMP snooping. Multicast group membership lists can consist of both user-defined and IGMP snooping-learned settings.

You can configure an IGMP snooping querier to support IGMP snooping in subnets without multicast interfaces because the multicast traffic does not need to be routed.

If a port spanning-tree, a port group, or a VLAN ID change occurs, the IGMP snooping-learned multicast groups from this port on the VLAN are deleted.

Joining a Multicast Group

Figure 1. Initial IGMP Join Message.

When a host connected to the device wants to join an IP multicast group and it is an IGMP version 2 client, it sends an unsolicited IGMP join message, specifying the IP multicast group to join. Alternatively, when the device receives a general query from the router, it forwards the query to all ports in the VLAN. IGMP version 1 or version 2 hosts wanting to join the multicast group respond by sending a join message to the device. The device CPU creates a multicast forwarding-table entry for the group if it is not already present. The CPU also adds the interface where the join message was received to the forwarding-table entry. The host associated with that interface receives multicast traffic for that multicast group.



Router A sends a general query to the device, which forwards the query to ports 2 through 5, which are all members of the same VLAN. Host 1 wants to join multicast group 224.1.2.3 and multicasts an IGMP membership report (IGMP join message) to the group. The device CPU uses the information in the IGMP report to set up a forwarding-table entry that includes the port numbers connected to Host 1 and to the router.

Table 2 IGMP Snooping Forwarding Table

Destination Address

Type of Packet

Ports

224.1.2.3

IGMP

1, 2

The device hardware can distinguish IGMP information packets from other packets for the multicast group. The information in the table tells the switching engine to send frames addressed to the 224.1.2.3 multicast IP address that are not IGMP packets to the router and to the host that has joined the group.

Figure 2. Second Host Joining a Multicast Group. If another host (for example, Host 4) sends an unsolicited IGMP join message for the same group, the CPU receives that message and adds the port number of Host 4 to the forwarding table. Because the forwarding table directs IGMP messages only to the CPU, the message is not flooded to other ports on the device. Any known multicast traffic is forwarded to the group and not to the CPU.

Table 3 Updated IGMP Snooping Forwarding Table

Destination Address

Type of Packet

Ports

224.1.2.3

IGMP

1, 2, 5

Leaving a Multicast Group

The router sends periodic multicast general queries, and the device forwards these queries through all ports in the VLAN. Interested hosts respond to the queries. If at least one host in the VLAN wants to receive multicast traffic, the router continues forwarding the multicast traffic to the VLAN. The device forwards multicast group traffic only to those hosts listed in the forwarding table for that IP multicast group maintained by IGMP snooping.

When hosts want to leave a multicast group, they can silently leave, or they can send a leave message. When the device receives a leave message from a host, it sends a group-specific query to learn if any other devices connected to that interface are interested in traffic for the specific multicast group. The device then updates the forwarding table for that MAC group so that only those hosts interested in receiving multicast traffic for the group are listed in the forwarding table. If the router receives no reports from a VLAN, it removes the group for the VLAN from its IGMP cache.

Immediate Leave

The device uses IGMP snooping Immediate Leave to remove from the forwarding table an interface that sends a leave message without the device sending group-specific queries to the interface. The VLAN interface is pruned from the multicast tree for the multicast group specified in the original leave message. Immediate Leave ensures optimal bandwidth management for all hosts on a switched network, even when multiple multicast groups are simultaneously in use.

Immediate Leave is only supported on IGMP version 2 hosts. IGMP version 2 is the default version for the device.


Note


You should only use the Immediate Leave feature on VLANs where a single host is connected to each port. If Immediate Leave is enabled in VLANs where more than one host is connected to a port, some hosts might inadvertently be dropped.


IGMP Configurable-Leave Timer

You can configure the time that the device waits after sending a group-specific query to determine if hosts are still interested in a specific multicast group. The IGMP leave response time can be configured from 100 to 5000 milliseconds. The timer can be set either globally or on a per-VLAN basis. The VLAN configuration of the leave time overrides the global configuration.

IGMP Report Suppression


Note


IGMP report suppression is supported only when the multicast query has IGMPv1 and IGMPv2 reports. This feature is not supported when the query includes IGMPv3 reports.


The device uses IGMP report suppression to forward only one IGMP report per multicast router query to multicast devices. When IGMP report suppression is enabled (the default), the device sends the first IGMP report from all hosts for a group to all the multicast routers. The device does not send the remaining IGMP reports for the group to the multicast routers. This feature prevents duplicate reports from being sent to the multicast devices.

If the multicast router query includes requests only for IGMPv1 and IGMPv2 reports, the device forwards only the first IGMPv1 or IGMPv2 report from all hosts for a group to all the multicast routers.

If the multicast router query also includes requests for IGMPv3 reports, the device forwards all IGMPv1, IGMPv2, and IGMPv3 reports for a group to the multicast devices.

If you disable IGMP report suppression, all IGMP reports are forwarded to the multicast routers.

IGMP Snooping and Device Stacks

IGMP snooping functions across the device stack; that is, IGMP control information from one device is distributed to all devices in the stack. Regardless of the stack member through which IGMP multicast data enters the stack, the data reaches the hosts that have registered for that group.

If a device in the stack fails or is removed from the stack, only the members of the multicast group that are on that device will not receive the multicast data. All other members of a multicast group on other devices in the stack continue to receive multicast data streams. However, multicast groups that are common for both Layer 2 and Layer 3 (IP multicast routing) might take longer to converge if the active device is removed.

IGMP Filtering and Throttling Overview

In some environments, for example, metropolitan or multiple-dwelling unit (MDU) installations, you might want to control the set of multicast groups to which a user on a device port can belong. You can control the distribution of multicast services, such as IP/TV, based on some type of subscription or service plan. You might also want to limit the number of multicast groups to which a user on a device port can belong.

With the IGMP filtering feature, you can filter multicast joins on a per-port basis by configuring IP multicast profiles and associating them with individual device ports. An IGMP profile can contain one or more multicast groups and specifies whether access to the group is permitted or denied. If an IGMP profile denying access to a multicast group is applied to a device port, the IGMP join report requesting the stream of IP multicast traffic is dropped, and the port is not allowed to receive IP multicast traffic from that group. If the filtering action permits access to the multicast group, the IGMP report from the port is forwarded for normal processing. You can also set the maximum number of IGMP groups that a Layer 2 interface can join.

IGMP filtering controls only group-specific query and membership reports, including join and leave reports. It does not control general IGMP queries. IGMP filtering has no relationship with the function that directs the forwarding of IP multicast traffic. The filtering feature operates in the same manner whether CGMP or MVR is used to forward the multicast traffic.

IGMP filtering applies only to the dynamic learning of IP multicast group addresses, not static configuration.

With the IGMP throttling feature, you can set the maximum number of IGMP groups that a Layer 2 interface can join. If the maximum number of IGMP groups is set, the IGMP snooping forwarding table contains the maximum number of entries, and the interface receives an IGMP join report, you can configure an interface to drop the IGMP report or to replace the randomly selected multicast entry with the received IGMP report.


Note


IGMPv3 join and leave messages are not supported on devices running IGMP filtering.


Default IGMP Configuration

This table displays the default IGMP configuration for the device.

Table 4 Default IGMP Configuration

Feature

Default Setting

Multilayer device as a member of a multicast group

No group memberships are defined.

Access to multicast groups

All groups are allowed on an interface.

IGMP version

Version 2 on all interfaces.

IGMP host-query message interval

60 seconds on all interfaces.

IGMP query timeout

60 seconds on all interfaces.

IGMP maximum query response time

10 seconds on all interfaces.

Multilayer device as a statically connected member

Disabled.

Default IGMP Snooping Configuration

This table displays the default IGMP snooping configuration for the device.

Table 5 Default IGMP Snooping Configuration

Feature

Default Setting

IGMP snooping

Enabled globally and per VLAN

Multicast routers

None configured

IGMP snooping Immediate Leave

Disabled

Static groups

None configured

TCN1 flood query count

2

TCN query solicitation

Disabled

IGMP snooping querier

Disabled

IGMP report suppression

Enabled

1 (1) TCN = Topology Change Notification

Default IGMP Filtering and Throttling Configuration

This table displays the default IGMP filtering and throttling configuration for the device.

Table 6 Default IGMP Filtering Configuration

Feature

Default Setting

IGMP filters

None applied.

IGMP maximum number of IGMP groups

No maximum set.

Note   

When the maximum number of groups is in the forwarding table, the default IGMP throttling action is to deny the IGMP report.

IGMP profiles

None defined.

IGMP profile action

Deny the range addresses.

How to Configure IGMP

Configuring the Device as a Member of a Group (CLI)

You can configure the device as a member of a multicast group and discover multicast reachability in a network. If all the multicast-capable routers and multilayer devices that you administer are members of a multicast group, pinging that group causes all of these devices to respond. The devices respond to ICMP echo-request packets addressed to a group of which they are members. Another example is the multicast trace-route tools provided in the software.


Caution


Performing this procedure might impact the CPU performance because the CPU will receive all data traffic for the group address.


This procedure is optional.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    interface interface-id

    4.    ip igmp join-group group-address

    5.    end

    6.    show ip igmp interface [interface-id]

    7.    copy running-config startup-config


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example:
    Device> enable
    
    
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     

    Step 2configure terminal


    Example:
    
    Device# configure terminal
    
    
     

    Enters the global configuration mode.

     
    Step 3interface interface-id


    Example:
    
    Device(config)# interface 
    gigabitethernet 1/0/1
    
    
     

    Specifies the Layer 3 interface on which you want to enable multicast routing, and enters interface configuration mode.

    The specified interface must be one of the following:

    • A routed port—A physical port that has been configured as a Layer 3 port by entering the no switchport interface configuration command. You will also need to enable IP PIM sparse-dense-mode on the interface, and join the interface as a statically connected member to an IGMP static group. For a configuration example, see Example: Interface Configuration as a Routed Port.
    • An SVI—A VLAN interface created by using the interface vlan vlan-id global configuration command. You will also need to enable IP PIM sparse-dense-mode on the VLAN, join the VLAN as a statically connected member to an IGMP static group, and then enable IGMP snooping on the VLAN, the IGMP static group, and physical interface. For a configuration example, see Example: Interface Configuration as an SVI.

    These interfaces must have IP addresses assigned to them.

     
    Step 4ip igmp join-group group-address


    Example:
    
    Device(config-if)# ip igmp 
    join-group 225.2.2.2
    
    
     

    Configures the device to join a multicast group.

    By default, no group memberships are defined.

    For group-address, specify the multicast IP address in dotted decimal notation.

     
    Step 5end


    Example:
    
    Device(config-if)# end
    
    
     

    Returns to privileged EXEC mode.

     
    Step 6show ip igmp interface [interface-id]


    Example:
    
    Device# show ip igmp interface
    
    
     

    Verifies your entries.

     
    Step 7copy running-config startup-config


    Example:
    
    Device# copy running-config 
    startup-config
    
    
     

    (Optional) Saves your entries in the configuration file.

     

    Controlling Access to IP Multicast Group (CLI)

    The device sends IGMP host-query messages to find which multicast groups have members on attached local networks. The device then forwards to these group members all packets addressed to the multicast group. You can place a filter on each interface to restrict the multicast groups that hosts on the subnet serviced by the interface can join.

    To limit the number of joins on the interface, configure the port for the filter which associates with the IGMP profile.

    This procedure is optional.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    ip igmp profile

      4.    permit

      5.    exit

      6.    interface interface-id

      7.    ip igmp filter filter_number

      8.    end

      9.    show ip igmp interface [interface-id]


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example:
      Device> enable
      
      
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.

       

      Step 2configure terminal


      Example:
      
      Device# configure terminal
      
      
       

      Enters the global configuration mode.

       
      Step 3ip igmp profile


      Example:
      Device(config)# ip igmp profile 10 
      Device(config-igmp-profile)# ?
      
       

      Enters an IGMP filter profile number from 1 to 4294967295.

      For additional information about configuring IGMP filter profiles, see Configuring IGMP Profiles (CLI).

       

      Step 4permit


      Example:
      Device(config-igmp-profile)# 
      permit 229.9.9.0
      
      
       

      Enters an IGMP profile configuration action. The following IGMP profile configuration actions are supported:

      • deny—Matching IP addresses are denied.
      • exit—Exits from the IGMP profile configuration mode.
      • no—Negates a command or set its defaults.
      • permit—Matching addresses are permitted.
      • range—Adds a range to the set.

       

      Step 5exit


      Example:
      
      Device(config-igmp-profile)# exit
      
      
       

      Returns to global configuration mode.

       
      Step 6interface interface-id


      Example:
      
      Device(config)# interface 
      gigabitethernet 1/0/1
      
      
       

      Specifies the interface to be configured, and enters interface configuration mode.

       
      Step 7ip igmp filter filter_number


      Example:
      Device(config-if)# ip igmp filter 10
      
      
       

      Specifies the IGMP filter profile number.

      For additional information about applying IGMP filter profiles, see Applying IGMP Profiles (CLI).

       

      Step 8end


      Example:
      Device(config-igmp-profile)# end
      
      
       

      Returns to privileged EXEC mode.

       
      Step 9show ip igmp interface [interface-id]


      Example:
      
      Device# show ip igmp interface
      
      
       

      Verifies your entries.

       

      Modifying the IGMP Host-Query Message Interval (CLI)

      The device periodically sends IGMP host-query messages to discover which multicast groups are present on attached networks. These messages are sent to the all-hosts multicast group (224.0.0.1) with a time-to-live (TTL) of 1. The device sends host-query messages to refresh its knowledge of memberships present on the network. If, after some number of queries, the software discovers that no local hosts are members of a multicast group, the software stops forwarding multicast packets to the local network from remote origins for that group and sends a prune message upstream toward the source.

      The device elects a PIM designated router (DR) for the LAN (subnet). The DR is the router or multilayer device with the highest IP address for IGMPv2. For IGMPv1, the DR is elected according to the multicast routing protocol that runs on the LAN. The designated router is responsible for sending IGMP host-query messages to all hosts on the LAN. In sparse mode, the designated router also sends PIM register and PIM join messages toward the RP router.

      This procedure is optional.

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    interface interface-id

        4.    ip igmp query-interval seconds

        5.    end

        6.    show ip igmp interface [interface-id]

        7.    copy running-config startup-config


      DETAILED STEPS
         Command or ActionPurpose
        Step 1 enable


        Example:
        Device> enable
        
        
         

        Enables privileged EXEC mode.

        • Enter your password if prompted.

         

        Step 2configure terminal


        Example:
        
        Device# configure terminal
        
        
         

        Enters the global configuration mode.

         
        Step 3interface interface-id


        Example:
        
        Device(config)# interface 
        gigabitethernet 1/0/1
        
        
         

        Specifies the Layer 3 interface on which you want to enable multicast routing, and enters interface configuration mode.

        The specified interface must be one of the following:

        • A routed port—A physical port that has been configured as a Layer 3 port by entering the no switchport interface configuration command. You will also need to enable IP PIM sparse-dense-mode on the interface, and join the interface as a statically connected member to an IGMP static group. For a configuration example, see Example: Interface Configuration as a Routed Port.
        • An SVI—A VLAN interface created by using the interface vlan vlan-id global configuration command. You will also need to enable IP PIM sparse-dense-mode on the VLAN, join the VLAN as a statically connected member to an IGMP static group, and then enable IGMP snooping on the VLAN, the IGMP static group, and physical interface. For a configuration example, see Example: Interface Configuration as an SVI.

        These interfaces must have IP addresses assigned to them.

         
        Step 4ip igmp query-interval seconds


        Example:
        
        Device(config-if)# ip igmp 
        query-interval 75
        
        
         

        Configures the frequency at which the designated router sends IGMP host-query messages.

        By default, the designated router sends IGMP host-query messages every 60 seconds to keep the IGMP overhead very low on hosts and networks.

        The range is 1 to 65535.

         
        Step 5end


        Example:
        
        Device(config-if)# end 
        
        
         

        Returns to privileged EXEC mode.

         
        Step 6show ip igmp interface [interface-id]


        Example:
        
        Device# show ip igmp interface
        
        
         

        Verifies your entries.

         
        Step 7copy running-config startup-config


        Example:
        
        Device# copy running-config 
        startup-config
        
        
         

        (Optional) Saves your entries in the configuration file.

         

        Changing the IGMP Query Timeout for IGMPv2 (CLI)

        If you are using IGMPv2, you can specify the period of time before the device takes over as the querier for the interface. By default, the device waits twice the query interval period controlled by the ip igmp query-interval interface configuration command. After that time, if the device has received no queries, it becomes the querier.

        This procedure is optional.

        SUMMARY STEPS

          1.    enable

          2.    configure terminal

          3.    interface interface-id

          4.    ip igmp querier-timeout seconds

          5.    end

          6.    show ip igmp interface [interface-id]

          7.    copy running-config startup-config


        DETAILED STEPS
           Command or ActionPurpose
          Step 1 enable


          Example:
          Device> enable
          
          
           

          Enables privileged EXEC mode.

          • Enter your password if prompted.

           

          Step 2configure terminal


          Example:
          
          Device# configure terminal
          
          
           

          Enters the global configuration mode.

           
          Step 3interface interface-id


          Example:
          
          Device(config)# interface 
          gigabitethernet 1/0/1
          
          
           

          Specifies the Layer 3 interface on which you want to enable multicast routing, and enters interface configuration mode.

          The specified interface must be one of the following:

          • A routed port—A physical port that has been configured as a Layer 3 port by entering the no switchport interface configuration command. You will also need to enable IP PIM sparse-dense-mode on the interface, and join the interface as a statically connected member to an IGMP static group. For a configuration example, see Example: Interface Configuration as a Routed Port.
          • An SVI—A VLAN interface created by using the interface vlan vlan-id global configuration command. You will also need to enable IP PIM sparse-dense-mode on the VLAN, join the VLAN as a statically connected member to an IGMP static group, and then enable IGMP snooping on the VLAN, the IGMP static group, and physical interface. For a configuration example, see Example: Interface Configuration as an SVI.

          These interfaces must have IP addresses assigned to them.

           
          Step 4ip igmp querier-timeout seconds


          Example:
          
          Device(config-if)# ip igmp 
          querier-timeout 120
          
          
           

          Specifies the IGMP query timeout.

          The default is 60 seconds (twice the query interval). The range is 60 to 300.

           
          Step 5end


          Example:
          
          Device(config-if)# end
          
          
           

          Returns to privileged EXEC mode.

           
          Step 6show ip igmp interface [interface-id]


          Example:
          
          Device# show ip igmp interface
          
          
           

          Verifies your entries.

           
          Step 7copy running-config startup-config


          Example:
          
          Device# copy running-config 
          startup-config
          
          
           

          (Optional) Saves your entries in the configuration file.

           

          Changing the Maximum Query Response Time for IGMPv2 (CLI)

          If you are using IGMPv2, you can change the maximum query response time advertised in IGMP queries. The maximum query response time enables the device to quickly detect that there are no more directly connected group members on a LAN. Decreasing the value enables the device to prune groups faster.

          This procedure is optional.

          SUMMARY STEPS

            1.    enable

            2.    configure terminal

            3.    interface interface-id

            4.    ip igmp query-max-response-time seconds

            5.    end

            6.    show ip igmp interface [interface-id]

            7.    copy running-config startup-config


          DETAILED STEPS
             Command or ActionPurpose
            Step 1 enable


            Example:
            Device> enable
            
            
             

            Enables privileged EXEC mode.

            • Enter your password if prompted.

             

            Step 2configure terminal


            Example:
            
            Device# configure terminal
            
            
             

            Enters the global configuration mode.

             
            Step 3interface interface-id


            Example:
            
            Device(config)# interface 
            gigabitethernet 1/0/1
            
            
             

            Specifies the Layer 3 interface on which you want to enable multicast routing, and enters interface configuration mode.

            The specified interface must be one of the following:

            • A routed port—A physical port that has been configured as a Layer 3 port by entering the no switchport interface configuration command. You will also need to enable IP PIM sparse-dense-mode on the interface, and join the interface as a statically connected member to an IGMP static group. For a configuration example, see Example: Interface Configuration as a Routed Port.
            • An SVI—A VLAN interface created by using the interface vlan vlan-id global configuration command. You will also need to enable IP PIM sparse-dense-mode on the VLAN, join the VLAN as a statically connected member to an IGMP static group, and then enable IGMP snooping on the VLAN, the IGMP static group, and physical interface. For a configuration example, see Example: Interface Configuration as an SVI.

            These interfaces must have IP addresses assigned to them.

             
            Step 4ip igmp query-max-response-time seconds


            Example:
            
            Device(config-if)# ip igmp 
            query-max-response-time 15
            
            
             

            Changes the maximum query response time advertised in IGMP queries.

            The default is 10 seconds. The range is 1 to 25.

             
            Step 5end


            Example:
            
            Device(config-if)# end
            
            
             

            Returns to privileged EXEC mode.

             
            Step 6show ip igmp interface [interface-id]


            Example:
            
            Device# show ip igmp interface 
            
            
             

            Verifies your entries.

             
            Step 7copy running-config startup-config


            Example:
            
            Device# copy running-config 
            startup-config 
            
            
             

            (Optional) Saves your entries in the configuration file.

             

            Configuring the Device as a Statically Connected Member (CLI)

            At various times, either there is not a group member on a network segment or a host that cannot report its group membership by using IGMP. However, you may want multicast traffic to be sent to that network segment. The following commands are used to pull multicast traffic down to a network segment:

            • ip igmp join-group—The device accepts the multicast packets in addition to forwarding them. Accepting the multicast packets prevents the device from fast switching.
            • ip igmp static-group—The device does not accept the packets itself, but only forwards them. This method enables fast switching. The outgoing interface appears in the IGMP cache, but the device itself is not a member, as evidenced by lack of an L (local) flag in the multicast route entry.

            This procedure is optional.

            SUMMARY STEPS

              1.    enable

              2.    configure terminal

              3.    interface interface-id

              4.    ip igmp static-group group-address

              5.    end

              6.    show ip igmp interface [interface-id]

              7.    copy running-config startup-config


            DETAILED STEPS
               Command or ActionPurpose
              Step 1 enable


              Example:
              Device> enable
              
              
               

              Enables privileged EXEC mode.

              • Enter your password if prompted.

               

              Step 2configure terminal


              Example:
              
              Device# configure terminal
              
              
               

              Enters the global configuration mode.

               
              Step 3interface interface-id


              Example:
              
              Device(config)# interface 
              gigabitethernet 1/0/1
              
              
               

              Specifies the Layer 3 interface on which you want to enable multicast routing, and enters interface configuration mode.

              The specified interface must be one of the following:

              • A routed port—A physical port that has been configured as a Layer 3 port by entering the no switchport interface configuration command. You will also need to enable IP PIM sparse-dense-mode on the interface, and join the interface as a statically connected member to an IGMP static group. For a configuration example, see Example: Interface Configuration as a Routed Port.
              • An SVI—A VLAN interface created by using the interface vlan vlan-id global configuration command. You will also need to enable IP PIM sparse-dense-mode on the VLAN, join the VLAN as a statically connected member to an IGMP static group, and then enable IGMP snooping on the VLAN, the IGMP static group, and physical interface. For a configuration example, see Example: Interface Configuration as an SVI.

              These interfaces must have IP addresses assigned to them.

               
              Step 4ip igmp static-group group-address


              Example:
              
              Device(config-if)# ip igmp static-group 239.100.100.101
              
              
               

              Configures the device as a statically connected member of a group.

              By default, this feature is disabled.

               
              Step 5end


              Example:
              
              Device(config-if)# end
              
              
               

              Returns to privileged EXEC mode.

               
              Step 6show ip igmp interface [interface-id]


              Example:
              
              Device# show ip igmp interface 
              gigabitethernet 1/0/1
              
              
               

              Verifies your entries.

               
              Step 7copy running-config startup-config


              Example:
              
              Device# copy running-config 
              startup-config 
              
              
               

              (Optional) Saves your entries in the configuration file.

               

              Configuring IGMP Profiles (CLI)

              To configure an IGMP profile, use the ip igmp profile global configuration command with a profile number to create an IGMP profile and to enter IGMP profile configuration mode. From this mode, you can specify the parameters of the IGMP profile to be used for filtering IGMP join requests from a port. When you are in IGMP profile configuration mode, you can create the profile by using these commands:

              • deny—Specifies that matching addresses are denied; this is the default.
              • exit—Exits from igmp-profile configuration mode.
              • no—Negates a command or returns to its defaults.
              • permit—Specifies that matching addresses are permitted.
              • range—Specifies a range of IP addresses for the profile. You can enter a single IP address or a range with a start and an end address.

              The default is for the device to have no IGMP profiles configured. When a profile is configured, if neither the permit nor deny keyword is included, the default is to deny access to the range of IP addresses.

              SUMMARY STEPS

                1.    enable

                2.    configure terminal

                3.    ip igmp profile profile number

                4.    permit | deny

                5.    range ip multicast address

                6.    end

                7.    show ip igmp profile profile number

                8.    copy running-config startup-config


              DETAILED STEPS
                 Command or ActionPurpose
                Step 1 enable


                Example:
                Device> enable
                
                
                 

                Enables privileged EXEC mode.

                • Enter your password if prompted.

                 

                Step 2configure terminal


                Example:
                
                Device# configure terminal
                
                
                 

                Enters the global configuration mode.

                 
                Step 3ip igmp profile profile number


                Example:
                
                Device(config)# ip igmp profile 3
                
                
                 

                Assigns a number to the profile you are configuring, and enters IGMP profile configuration mode. The profile number range is 1 to 4294967295.

                Note    To delete a profile, use the no ip igmp profile profile number global configuration command.
                 
                Step 4permit | deny

                Example:
                
                Device(config-igmp-profile)# permit
                
                
                 

                (Optional) Sets the action to permit or deny access to the IP multicast address. If no action is configured, the default for the profile is to deny access.

                 
                Step 5range ip multicast address


                Example:
                
                Device(config-igmp-profile)# range 229.9.9.0
                
                
                 

                Enters the IP multicast address or range of IP multicast addresses to which access is being controlled. If entering a range, enter the low IP multicast address, a space, and the high IP multicast address.

                You can use the range command multiple times to enter multiple addresses or ranges of addresses.

                Note   

                To delete an IP multicast address or range of IP multicast addresses, use the no range ip multicast address IGMP profile configuration command.

                 
                Step 6end


                Example:
                
                Device(config-igmp-profile)# end
                
                
                 

                Returns to privileged EXEC mode.

                 
                Step 7show ip igmp profile profile number


                Example:
                
                Device# show ip igmp profile 3
                
                
                 

                Verifies the profile configuration.

                 
                Step 8copy running-config startup-config


                Example:
                
                Device# copy running-config startup-config
                
                
                 

                (Optional) Saves your entries in the configuration file.

                 

                Applying IGMP Profiles (CLI)

                To control access as defined in an IGMP profile, use the ip igmp filter interface configuration command to apply the profile to the appropriate interfaces. You can apply IGMP profiles only to Layer 2 access ports; you cannot apply IGMP profiles to routed ports or SVIs. You cannot apply profiles to ports that belong to an EtherChannel port group. You can apply a profile to multiple interfaces, but each interface can have only one profile applied to it.

                SUMMARY STEPS

                  1.    enable

                  2.    configure terminal

                  3.    interface interface-id

                  4.    ip igmp filter profile number

                  5.    end

                  6.    show running-config interface interface-id

                  7.    copy running-config startup-config


                DETAILED STEPS
                   Command or ActionPurpose
                  Step 1 enable


                  Example:
                  Device> enable
                  
                  
                   

                  Enables privileged EXEC mode.

                  • Enter your password if prompted.

                   

                  Step 2configure terminal


                  Example:
                  
                  Device# configure terminal
                  
                  
                   

                  Enters the global configuration mode.

                   
                  Step 3interface interface-id


                  Example:
                  
                  Device(config)# interface gigabitethernet1/0/1
                  
                  
                   

                  Specifies the physical interface, and enters interface configuration mode. The interface must be a Layer 2 port that does not belong to an EtherChannel port group.

                   
                  Step 4ip igmp filter profile number


                  Example:
                  
                  Device(config-if)# ip igmp filter 321
                  
                  
                   

                  Applies the specified IGMP profile to the interface. The range is 1 to 4294967295.

                  Note   

                  To remove a profile from an interface, use the no ip igmp filter profile number interface configuration command.

                   
                  Step 5end


                  Example:
                  
                  Device(config-if)# end
                  
                  
                   

                  Returns to privileged EXEC mode.

                   
                  Step 6show running-config interface interface-id


                  Example:
                  
                  Device# show running-config interface gigabitethernet1/0/1
                  
                  
                   

                  Verifies the configuration.

                   
                  Step 7copy running-config startup-config


                  Example:
                  
                  Device# copy running-config startup-config
                  
                  
                   

                  (Optional) Saves your entries in the configuration file.

                   

                  Setting the Maximum Number of IGMP Groups (CLI)

                  You can set the maximum number of IGMP groups that a Layer 2 interface can join by using the ip igmp max-groups interface configuration command. Use the no form of this command to set the maximum back to the default, which is no limit.

                  This restriction can be applied to Layer 2 ports only; you cannot set a maximum number of IGMP groups on routed ports or SVIs. You also can use this command on a logical EtherChannel interface but cannot use it on ports that belong to an EtherChannel port group.

                  Beginning in privileged EXEC mode, follow these steps to set the maximum number of IGMP groups in the forwarding table:

                  SUMMARY STEPS

                    1.    enable

                    2.    configure terminal

                    3.    interface interface-id

                    4.    ip igmp max-groups number

                    5.    end

                    6.    show running-config interface interface-id

                    7.    copy running-config startup-config


                  DETAILED STEPS
                     Command or ActionPurpose
                    Step 1 enable


                    Example:
                    Device> enable
                    
                    
                     

                    Enables privileged EXEC mode.

                    • Enter your password if prompted.

                     

                    Step 2configure terminal


                    Example:
                    
                    Device# configure terminal
                    
                    
                     

                    Enters the global configuration mode.

                     
                    Step 3interface interface-id


                    Example:
                    
                    Device(config)# interface gigabitethernet1/0/2
                    
                    
                     

                    Specifies the interface to be configured, and enters interface configuration mode. The interface can be a Layer 2 port that does not belong to an EtherChannel group or a EtherChannel interface.

                     
                    Step 4ip igmp max-groups number


                    Example:
                    
                    Device(config-if)# ip igmp max-groups 20
                    
                    
                     

                    Sets the maximum number of IGMP groups that the interface can join. The range is 0 to 4294967294. The default is to have no maximum set.

                    Note   

                    The device supports a maximum number of 4096 Layer 2 IGMP groups and 2048 Layer 3 IGMP groups.

                     
                    Step 5end


                    Example:
                    
                    Device(config-if)# end
                    
                    
                     

                    Returns to privileged EXEC mode.

                     
                    Step 6show running-config interface interface-id


                    Example:
                    
                    Device# show running-config interface gigabitethernet1/0/1
                    
                    
                     

                    Verifies your entries.

                     
                    Step 7copy running-config startup-config


                    Example:
                    
                    Device# copy running-config startup-config
                    
                    
                     

                    (Optional) Saves your entries in the configuration file.

                     

                    Configuring the IGMP Throttling Action (CLI)

                    After you set the maximum number of IGMP groups that a Layer 2 interface can join, you can configure an interface to replace the existing group with the new group for which the IGMP report was received by using the ip igmp max-groups action replace interface configuration command. Use the no form of this command to return to the default, which is to drop the IGMP join report.

                    Follow these guidelines when configuring the IGMP throttling action:

                    • This restriction can be applied only to Layer 2 ports. You can use this command on a logical EtherChannel interface but cannot use it on ports that belong to an EtherChannel port group.
                    • When the maximum group limitation is set to the default (no maximum), entering the ip igmp max-groups action {deny | replace} command has no effect.
                    • If you configure the throttling action and set the maximum group limitation after an interface has added multicast entries to the forwarding table, the forwarding-table entries are either aged out or removed, depending on the throttling action.
                      • If you configure the throttling action as deny, the entries that were previously in the forwarding table are not removed but are aged out. After these entries are aged out and the maximum number of entries is in the forwarding table, the device drops the next IGMP report received on the interface.
                      • If you configure the throttling action as replace, the entries that were previously in the forwarding table are removed. When the maximum number of entries is in the forwarding table, the device replaces a randomly selected entry with the received IGMP report. To prevent the device from removing the forwarding-table entries, you can configure the IGMP throttling action before an interface adds entries to the forwarding table.
                    SUMMARY STEPS

                      1.    enable

                      2.    configure terminal

                      3.    interface interface-id

                      4.    ip igmp max-groups action {deny | replace}

                      5.    end

                      6.    show running-config interface interface-id

                      7.    copy running-config startup-config


                    DETAILED STEPS
                       Command or ActionPurpose
                      Step 1 enable


                      Example:
                      Device> enable
                      
                      
                       

                      Enables privileged EXEC mode.

                      • Enter your password if prompted.

                       

                      Step 2configure terminal


                      Example:
                      
                      Device# configure terminal
                      
                      
                       

                      Enters the global configuration mode.

                       
                      Step 3interface interface-id


                      Example:
                      
                      Device(config)# interface gigabitethernet 1/0/1
                      
                      
                       

                      Specifies the physical interface to be configured, and enters interface configuration mode. The interface can be a Layer 2 port that does not belong to an EtherChannel group or an EtherChannel interface. The interface cannot be a trunk port.

                       
                      Step 4ip igmp max-groups action {deny | replace}


                      Example:
                      
                      Device(config-if)# ip igmp max-groups action replace
                      
                      
                       

                      When an interface receives an IGMP report and the maximum number of entries is in the forwarding table, specifies the action that the interface takes:

                      • deny—Drops the report.
                      • replace—Replaces the existing group with the new group for which the IGMP report was received.
                      Note   

                      To return to the default action of dropping the report, use the no ip igmp max-groups action interface configuration command.

                       
                      Step 5end


                      Example:
                      
                      Device(config-if)# end
                      
                      
                       

                      Returns to privileged EXEC mode.

                       
                      Step 6show running-config interface interface-id


                      Example:
                      
                      Device# show running-config interface gigabitethernet1/0/1
                      
                      
                       

                      Verifies your entries.

                       
                      Step 7copy running-config startup-config


                      Example:
                      
                      Device# copy running-config startup-config
                      
                      
                       

                      (Optional) Saves your entries in the configuration file.

                       

                      Configuring the Device to Forward Multicast Traffic in the Absence of Directly Connected IGMP Hosts

                      Perform this optional task to configure the device to forward multicast traffic in the absence of directly connected IGMP hosts.

                      SUMMARY STEPS

                        1.    enable

                        2.    configure terminal

                        3.    interface type number

                        4.    Do one of the following:

                        • ip igmp join-group group-address
                        • ip igmp static-group {* | group-address [source source-address]}

                        5.    end

                        6.    show ip igmp interface [interface-type interface-number]


                      DETAILED STEPS
                         Command or ActionPurpose
                        Step 1 enable


                        Example:
                        Device> enable
                         

                        Enables privileged EXEC mode.

                        • Enter your password if prompted.
                         
                        Step 2 configure terminal


                        Example:
                        Device# configure terminal
                         

                        Enters global configuration mode.

                         
                        Step 3 interface type number


                        Example:
                        Device(config)# interface gigabitethernet 1
                         

                        Enters interface configuration mode.

                        • For the type and number arguments, specify an interface that is connected to hosts.
                         
                        Step 4Do one of the following:
                        • ip igmp join-group group-address
                        • ip igmp static-group {* | group-address [source source-address]}


                        Example:
                        Device(config-if)# ip igmp join-group 225.2.2.2 


                        Example:
                        Device(config-if)# ip igmp static-group 225.2.2.2
                         
                        The first sample shows how to configure an interface on the device to join the specified group.
                        • With this method, the device accepts the multicast packets in addition to forwarding them. Accepting the multicast packets prevents the device from fast switching.
                        The second example shows how to configure static group membership entries on an interface.
                        • With this method, the device does not accept the packets itself, but only forwards them. Hence, this method allows fast switching. The outgoing interface appears in the IGMP cache, but the device itself is not a member, as evidenced by lack of an “L” (local) flag in the multicast route entry.
                         
                        Step 5 end


                        Example:
                        Device(config-if)# end
                         

                        Returns to privileged EXEC mode.

                         
                        Step 6 show ip igmp interface [interface-type interface-number]


                        Example:
                        Device# show ip igmp interface 
                         

                        (Optional) Displays multicast-related information about an interface.

                         

                        Controlling Access to an SSM Network Using IGMP Extended Access Lists

                        Perform this optional task to control access to an SSM network by using an IGMP extended access list that filters SSM traffic based on source address, group address, or both.

                        SUMMARY STEPS

                          1.    enable

                          2.    configure terminal

                          3.    ip multicast-routing [distributed]

                          4.    ip pim ssm {default | range access-list}

                          5.    ip access-list extended access-list -name

                          6.    deny igmp source source-wildcard destination destination-wildcard [igmp-type] [precedence precedence] [tos tos] [log] [time-range time-range-name] [fragments]

                          7.    permit igmp source source-wildcard destination destination-wildcard [igmp-type] [precedence precedence] [tos tos] [log] [time-range time-range-name] [fragments]

                          8.    exit

                          9.    interface type number

                          10.    ip igmp access-group access-list

                          11.    ip pim sparse-mode

                          12.    Repeat Steps 1 through 11 on all interfaces that require access control of SSM channel membership.

                          13.    ip igmp version 3

                          14.    Repeat Step 13 on all host-facing interfaces.

                          15.    end


                        DETAILED STEPS
                           Command or ActionPurpose
                          Step 1 enable


                          Example:
                          Device> enable
                           

                          Enables privileged EXEC mode.

                          • Enter your password if prompted.
                           
                          Step 2 configure terminal


                          Example:
                          Device# configure terminal
                           

                          Enters global configuration mode.

                           
                          Step 3 ip multicast-routing [distributed]


                          Example:
                          Device(config)# ip multicast-routing distributed
                           

                          Enables IP multicast routing.

                          • The distributed keyword is required for IPv4 multicast..
                           
                          Step 4 ip pim ssm {default | range access-list}


                          Example:
                          Device(config)# ip pim ssm default
                           

                          Configures SSM service.

                          • The default keyword defines the SSM range access list as 232/8.
                          • The range keyword specifies the standard IP access list number or name that defines the SSM range.
                           
                          Step 5 ip access-list extended access-list -name


                          Example:
                          Device(config)# ip access-list extended mygroup
                           

                          Specifies an extended named IP access list.

                           
                          Step 6 deny igmp source source-wildcard destination destination-wildcard [igmp-type] [precedence precedence] [tos tos] [log] [time-range time-range-name] [fragments]


                          Example:
                          Device(config-ext-nacl)# deny igmp host 10.1.2.3 any
                           

                          (Optional) Filters the specified source address or group address from the IGMP report, thereby restricting hosts on a subnet from membership to the (S, G) channel.

                          • Repeat this step to restrict hosts on a subnet membership to other (S, G) channels. (These sources should be more specific than a subsequent permit statement because any sources or groups not specifically permitted are denied.)
                          • Remember that the access list ends in an implicit deny statement.
                          • This example shows how to create a deny statement that filters all groups for source 10.1.2.3, which effectively denies the source.
                           
                          Step 7 permit igmp source source-wildcard destination destination-wildcard [igmp-type] [precedence precedence] [tos tos] [log] [time-range time-range-name] [fragments]


                          Example:
                          Device(config-ext-nacl)# permit igmp any any
                           

                          Allows a source address or group address in an IGMP report to pass the IP access list.

                          • You must have at least one permit statement in an access list.
                          • Repeat this step to allow other sources to pass the IP access list.
                          • This example shows how to allow group membership to sources and groups not denied by prior deny statements.
                           
                          Step 8 exit


                          Example:
                          Device(config-ext-nacl)# exit
                           

                          Exits the current configuration session and returns to global configuration mode.

                           
                          Step 9 interface type number

                          Example:
                          Device(config)# interface ethernet 0
                           

                          Selects an interface that is connected to hosts on which IGMPv3 can be enabled.

                           
                          Step 10 ip igmp access-group access-list


                          Example:
                          Device(config-if)# ip igmp access-group mygroup 
                           

                          Applies the specified access list to IGMP reports.

                           
                          Step 11 ip pim sparse-mode


                          Example:
                          Device(config-if)# ip pim sparse-mode
                           

                          Enables PIM-SM on the interface.

                          Note   

                          You must use sparse mode.

                           
                          Step 12 Repeat Steps 1 through 11 on all interfaces that require access control of SSM channel membership.  

                          --

                           
                          Step 13 ip igmp version 3


                          Example:
                          Device(config-if)# ip igmp version 3
                           

                          Enables IGMPv3 on this interface. The default version of IGMP is IGMP version 2. Version 3 is required by SSM.

                           
                          Step 14 Repeat Step 13 on all host-facing interfaces.  

                          --

                           
                          Step 15 end


                          Example:
                          Device(config-if)# end
                           

                          Returns to privileged EXEC mode.

                           

                          How to Configure IGMP Snooping

                          Enabling or Disabling IGMP Snooping on a Device (CLI)

                          By default, IGMP snooping is globally enabled on the device. When globally enabled or disabled, it is also enabled or disabled in all existing VLAN interfaces. IGMP snooping is by default enabled on all VLANs, but can be enabled and disabled on a per-VLAN basis.

                          Global IGMP snooping overrides the VLAN IGMP snooping. If global snooping is disabled, you cannot enable VLAN snooping. If global snooping is enabled, you can enable or disable VLAN snooping.

                          SUMMARY STEPS

                            1.    enable

                            2.    configure terminal

                            3.    ip igmp snooping

                            4.    end

                            5.    copy running-config startup-config


                          DETAILED STEPS
                             Command or ActionPurpose
                            Step 1 enable


                            Example:
                            Device> enable
                            
                            
                             

                            Enables privileged EXEC mode.

                            • Enter your password if prompted.

                             

                            Step 2configure terminal


                            Example:
                            
                            Device# configure terminal
                            
                            
                             

                            Enters the global configuration mode.

                             
                            Step 3ip igmp snooping


                            Example:
                            
                            Device(config)# ip igmp snooping
                            
                            
                             

                            Globally enables IGMP snooping in all existing VLAN interfaces.

                            Note   

                            To globally disable IGMP snooping on all VLAN interfaces, use the no ip igmp snooping global configuration command.

                             
                            Step 4end


                            Example:
                            
                            Device(config)# end
                            
                            
                             

                            Returns to privileged EXEC mode.

                             
                            Step 5copy running-config startup-config


                            Example:
                            
                            Device# copy running-config startup-config 
                            
                            
                             

                            (Optional) Saves your entries in the configuration file.

                             
                            Related Concepts

                            Enabling or Disabling IGMP Snooping on a VLAN Interface (CLI)

                            SUMMARY STEPS

                              1.    enable

                              2.    configure terminal

                              3.    ip igmp snooping vlan vlan-id

                              4.    end

                              5.    copy running-config startup-config


                            DETAILED STEPS
                               Command or ActionPurpose
                              Step 1 enable


                              Example:
                              Device> enable
                              
                              
                               

                              Enables privileged EXEC mode.

                              • Enter your password if prompted.

                               

                              Step 2configure terminal


                              Example:
                              
                              Device# configure terminal
                              
                              
                               

                              Enters the global configuration mode.

                               
                              Step 3ip igmp snooping vlan vlan-id


                              Example:
                              
                              Device(config)# ip igmp snooping vlan 7
                              
                              
                               

                              Enables IGMP snooping on the VLAN interface. The VLAN ID range is 1 to 1001 and 1006 to 4094.

                              IGMP snooping must be globally enabled before you can enable VLAN snooping.

                              Note   

                              To disable IGMP snooping on a VLAN interface, use the no ip igmp snooping vlan vlan-id global configuration command for the specified VLAN number.

                               
                              Step 4end


                              Example:
                              
                              Device(config)# end
                              
                              
                               

                              Returns to privileged EXEC mode.

                               
                              Step 5copy running-config startup-config


                              Example:
                              
                              Device# copy running-config startup-config
                              
                              
                               

                              (Optional) Saves your entries in the configuration file.

                               

                              Setting the Snooping Method (CLI)

                              Multicast-capable router ports are added to the forwarding table for every Layer 2 multicast entry. The device learns of the ports through one of these methods:

                              • Snooping on IGMP queries
                              • Statically connecting to a multicast router port using the ip igmp snooping mrouter global configuration command

                              Beginning in privileged EXEC mode, follow these steps to alter the method in which a VLAN interface accesses a multicast router:

                              SUMMARY STEPS

                                1.    enable

                                2.    configure terminal

                                3.    ip igmp snooping vlan vlan-id mrouter interface {GigabitEthernet | Port-Channel | TenGigabitEthernet}

                                4.    end

                                5.    show ip igmp snooping

                                6.    copy running-config startup-config


                              DETAILED STEPS
                                 Command or ActionPurpose
                                Step 1 enable


                                Example:
                                Device> enable
                                
                                
                                 

                                Enables privileged EXEC mode.

                                • Enter your password if prompted.

                                 

                                Step 2configure terminal


                                Example:
                                
                                Device# configure terminal
                                
                                
                                 

                                Enters the global configuration mode.

                                 
                                Step 3ip igmp snooping vlan vlan-id mrouter interface {GigabitEthernet | Port-Channel | TenGigabitEthernet}


                                Example:
                                Device(config)# ip igmp snooping 
                                vlan 1 mrouter interface GigabitEthernet1/0/3
                                
                                
                                 

                                Enables IGMP snooping on a VLAN. The VLAN ID range is 1 to 1001 and 1006 to 4094.

                                 
                                Step 4end


                                Example:
                                
                                Device(config)# end
                                
                                
                                 

                                Returns to privileged EXEC mode.

                                 
                                Step 5show ip igmp snooping


                                Example:
                                
                                Device# show ip igmp snooping
                                
                                
                                 

                                Verifies the configuration.

                                 
                                Step 6copy running-config startup-config


                                Example:
                                
                                Device# copy running-config startup-config
                                
                                
                                 

                                (Optional) Saves your entries in the configuration file.

                                 

                                Configuring a Multicast Router Port (CLI)

                                To add a multicast router port (add a static connection to a multicast router), use the ip igmp snooping vlan mrouter global configuration command on the device.


                                Note


                                Static connections to multicast routers are supported only on device ports.


                                SUMMARY STEPS

                                  1.    enable

                                  2.    configure terminal

                                  3.    ip igmp snooping vlan vlan-id mrouter interface interface-id

                                  4.    end

                                  5.    show ip igmp snooping mrouter [vlan vlan-id]

                                  6.    copy running-config startup-config


                                DETAILED STEPS
                                   Command or ActionPurpose
                                  Step 1 enable


                                  Example:
                                  Device> enable
                                  
                                  
                                   

                                  Enables privileged EXEC mode.

                                  • Enter your password if prompted.

                                   

                                  Step 2configure terminal


                                  Example:
                                  
                                  Device# configure terminal
                                  
                                  
                                   

                                  Enters the global configuration mode.

                                   
                                  Step 3ip igmp snooping vlan vlan-id mrouter interface interface-id


                                  Example:
                                  
                                  Device(config)# ip igmp snooping vlan 5 mrouter interface gigabitethernet1/0/1 
                                  
                                  
                                   

                                  Specifies the multicast router VLAN ID and the interface to the multicast router.

                                  • The VLAN ID range is 1 to 1001 and 1006 to 4094.
                                  • The interface can be a physical interface or a port channel. The port-channel range is 1 to 128.
                                  Note   

                                  To remove a multicast router port from the VLAN, use the no ip igmp snooping vlan vlan-id mrouter interface interface-id global configuration command.

                                   
                                  Step 4end


                                  Example:
                                  
                                  Device(config)# end
                                  
                                  
                                   

                                  Returns to privileged EXEC mode.

                                   
                                  Step 5show ip igmp snooping mrouter [vlan vlan-id]


                                  Example:
                                  
                                  Device# show ip igmp snooping mrouter vlan 5
                                  
                                  
                                   

                                  Verifies that IGMP snooping is enabled on the VLAN interface.

                                   
                                  Step 6copy running-config startup-config


                                  Example:
                                  
                                  Device# copy running-config startup-config
                                  
                                  
                                   

                                  (Optional) Saves your entries in the configuration file.

                                   

                                  Configuring a Host Statically to Join a Group (CLI)

                                  Hosts or Layer 2 ports normally join multicast groups dynamically, but you can also statically configure a host on an interface.

                                  SUMMARY STEPS

                                    1.    enable

                                    2.    configure terminal

                                    3.    ip igmp snooping vlan vlan-id static ip_address interface interface-id

                                    4.    end

                                    5.    show ip igmp snooping groups

                                    6.    copy running-config startup-config


                                  DETAILED STEPS
                                     Command or ActionPurpose
                                    Step 1 enable


                                    Example:
                                    Device> enable
                                    
                                    
                                     

                                    Enables privileged EXEC mode.

                                    • Enter your password if prompted.

                                     

                                    Step 2configure terminal


                                    Example:
                                    
                                    Device# configure terminal
                                    
                                    
                                     

                                    Enters the global configuration mode.

                                     
                                    Step 3ip igmp snooping vlan vlan-id static ip_address interface interface-id


                                    Example:
                                    
                                    Device(config)# ip igmp snooping vlan 105 static 230.0.0.1 interface gigabitethernet1/0/1
                                    
                                    
                                     

                                    Statically configures a Layer 2 port as a member of a multicast group:

                                    • vlan-id is the multicast group VLAN ID. The range is 1 to 1001 and 1006 to 4094.
                                    • ip-address is the group IP address.
                                    • interface-id is the member port. It can be a physical interface or a port channel (1 to 128).
                                    Note   

                                    To remove the Layer 2 port from the multicast group, use the no ip igmp snooping vlan vlan-id static mac-address interface interface-id global configuration command.

                                     
                                    Step 4end


                                    Example:
                                    
                                    Device(config)# end
                                    
                                    
                                     

                                    Returns to privileged EXEC mode.

                                     
                                    Step 5show ip igmp snooping groups


                                    Example:
                                    
                                    Device# show ip igmp snooping groups
                                    
                                    
                                     

                                    Verifies the member port and the IP address.

                                     
                                    Step 6copy running-config startup-config


                                    Example:
                                    
                                    Device# copy running-config startup-config
                                    
                                    
                                     

                                    (Optional) Saves your entries in the configuration file.

                                     

                                    Enabling IGMP Immediate Leave (CLI)

                                    When you enable IGMP Immediate Leave, the device immediately removes a port when it detects an IGMP Version 2 leave message on that port. You should only use the Immediate-Leave feature when there is a single receiver present on every port in the VLAN.


                                    Note


                                    Immediate Leave is supported only on IGMP Version 2 hosts. IGMP Version 2 is the default version for the device.


                                    SUMMARY STEPS

                                      1.    enable

                                      2.    configure terminal

                                      3.    ip igmp snooping vlan vlan-id immediate-leave

                                      4.    end

                                      5.    show ip igmp snooping vlan vlan-id

                                      6.    copy running-config startup-config


                                    DETAILED STEPS
                                       Command or ActionPurpose
                                      Step 1 enable


                                      Example:
                                      Device> enable
                                      
                                      
                                       

                                      Enables privileged EXEC mode.

                                      • Enter your password if prompted.

                                       

                                      Step 2configure terminal


                                      Example:
                                      
                                      Device# configure terminal
                                      
                                      
                                       

                                      Enters the global configuration mode.

                                       
                                      Step 3ip igmp snooping vlan vlan-id immediate-leave


                                      Example:
                                      
                                      Device(config)# ip igmp snooping vlan 21 immediate-leave 
                                      
                                      
                                       

                                      Enables IGMP Immediate Leave on the VLAN interface.

                                      Note   

                                      To disable IGMP Immediate Leave on a VLAN, use the no ip igmp snooping vlan vlan-id immediate-leave global configuration command.

                                       
                                      Step 4end


                                      Example:
                                      
                                      Device(config)# end
                                      
                                      
                                       

                                      Returns to privileged EXEC mode.

                                       
                                      Step 5show ip igmp snooping vlan vlan-id


                                      Example:
                                      
                                      Device# show ip igmp snooping vlan 21 
                                      
                                      
                                       

                                      Verifies that Immediate Leave is enabled on the VLAN interface.

                                       
                                      Step 6copy running-config startup-config


                                      Example:
                                      
                                      Device# copy running-config startup-config
                                      
                                      
                                       

                                      (Optional) Saves your entries in the configuration file.

                                       

                                      Configuring the IGMP Leave Timer (CLI)

                                      Follow these guidelines when configuring the IGMP leave timer:

                                      • You can configure the leave time globally or on a per-VLAN basis.
                                      • Configuring the leave time on a VLAN overrides the global setting.
                                      • The default leave time is 1000 milliseconds.
                                      • The IGMP configurable leave time is only supported on hosts running IGMP Version 2. IGMP version 2 is the default version for the device.
                                      • The actual leave latency in the network is usually the configured leave time. However, the leave time might vary around the configured time, depending on real-time CPU load conditions, network delays and the amount of traffic sent through the interface.
                                      SUMMARY STEPS

                                        1.    enable

                                        2.    configure terminal

                                        3.    ip igmp snooping last-member-query-interval time

                                        4.    ip igmp snooping vlan vlan-id last-member-query-interval time

                                        5.    end

                                        6.    show ip igmp snooping

                                        7.    copy running-config startup-config


                                      DETAILED STEPS
                                         Command or ActionPurpose
                                        Step 1 enable


                                        Example:
                                        Device> enable
                                        
                                        
                                         

                                        Enables privileged EXEC mode.

                                        • Enter your password if prompted.

                                         

                                        Step 2configure terminal


                                        Example:
                                        
                                        Device# configure terminal
                                        
                                        
                                         

                                        Enters the global configuration mode.

                                         
                                        Step 3ip igmp snooping last-member-query-interval time


                                        Example:
                                        
                                        Device(config)# ip igmp snooping last-member-query-interval 1000
                                        
                                        
                                         

                                        Configures the IGMP leave timer globally. The range is 100 to 32768 milliseconds. The default is 1000 seconds.

                                        Note   

                                        To globally reset the IGMP leave timer to the default setting, use the no ip igmp snooping last-member-query-interval global configuration command.

                                         
                                        Step 4ip igmp snooping vlan vlan-id last-member-query-interval time


                                        Example:
                                        
                                        Device(config)# ip igmp snooping vlan 210 last-member-query-interval 1000
                                        
                                        
                                         

                                        (Optional) Configures the IGMP leave time on the VLAN interface. The range is 100 to 32768 milliseconds.

                                        Note   

                                        Configuring the leave time on a VLAN overrides the globally configured timer.

                                        Note   

                                        To remove the configured IGMP leave-time setting from the specified VLAN, use the no ip igmp snooping vlan vlan-id last-member-query-interval global configuration command.

                                         
                                        Step 5end


                                        Example:
                                        
                                        Device(config)# end
                                        
                                        
                                         

                                        Returns to privileged EXEC mode.

                                         
                                        Step 6show ip igmp snooping


                                        Example:
                                        
                                        Device# show ip igmp snooping
                                        
                                        
                                         

                                        (Optional) Displays the configured IGMP leave time.

                                         
                                        Step 7copy running-config startup-config


                                        Example:
                                        
                                        Device# copy running-config startup-config
                                        
                                        
                                         

                                        (Optional) Saves your entries in the configuration file.

                                         

                                        Configuring the IGMP Robustness-Variable (CLI)

                                        Use the following procedure to configure the IGMP robustness variable on the device.

                                        The robustness variable is the integer used by IGMP snooping during calculations for IGMP messages. The robustness variable provides fine tuning to allow for expected packet loss.

                                        SUMMARY STEPS

                                          1.    enable

                                          2.    configure terminal

                                          3.    ip igmp snooping robustness-variable count

                                          4.    ip igmp snooping vlan vlan-id robustness-variable count

                                          5.    end

                                          6.    show ip igmp snooping

                                          7.    copy running-config startup-config


                                        DETAILED STEPS
                                           Command or ActionPurpose
                                          Step 1 enable


                                          Example:
                                          Device> enable
                                          
                                          
                                           

                                          Enables privileged EXEC mode.

                                          • Enter your password if prompted.

                                           

                                          Step 2configure terminal


                                          Example:
                                          
                                          Device# configure terminal
                                          
                                          
                                           

                                          Enters the global configuration mode.

                                           
                                          Step 3ip igmp snooping robustness-variable count


                                          Example:
                                          
                                          Device(config)# ip igmp snooping
                                           robustness-variable 3
                                          
                                          
                                           

                                          Configures the IGMP robustness variable. The range is 1 to 3 times.

                                          The recommended value for the robustness variable is 2. Use this command to change the value of the robustness variable for IGMP snooping from the default (2) to a specified value.

                                           
                                          Step 4ip igmp snooping vlan vlan-id robustness-variable count


                                          Example:
                                          
                                          Device(config)#ip igmp snooping vlan 100 robustness-variable 3
                                          
                                          
                                           

                                          (Optional) Configures the IGMP robustness variable on the VLAN interface. The range is 1 to 3 times. The recommended value for the robustness variable is 2.

                                          Note   

                                          Configuring the robustness variable count on a VLAN overrides the globally configured value.

                                           
                                          Step 5end


                                          Example:
                                          
                                          Device(config)# end
                                          
                                          
                                           

                                          Returns to privileged EXEC mode.

                                           
                                          Step 6show ip igmp snooping


                                          Example:
                                          
                                          Device# show ip igmp snooping
                                          
                                          
                                           

                                          (Optional) Displays the configured IGMP robustness variable count.

                                           
                                          Step 7copy running-config startup-config


                                          Example:
                                          
                                          Device# copy running-config startup-config
                                          
                                          
                                           

                                          (Optional) Saves your entries in the configuration file.

                                           

                                          Configuring the IGMP Last Member Query Count (CLI)

                                          To configure the number of times the device sends IGMP group-specific or group-source-specific (with IGMP version 3) query messages in response to receiving a group-specific or group-source-specific leave message, use this command.

                                          SUMMARY STEPS

                                            1.    enable

                                            2.    configure terminal

                                            3.    ip igmp snooping last-member-query-count count

                                            4.    ip igmp snooping vlan vlan-id last-member-query-count count

                                            5.    end

                                            6.    show ip igmp snooping

                                            7.    copy running-config startup-config


                                          DETAILED STEPS
                                             Command or ActionPurpose
                                            Step 1 enable


                                            Example:
                                            Device> enable
                                            
                                            
                                             

                                            Enables privileged EXEC mode.

                                            • Enter your password if prompted.

                                             

                                            Step 2configure terminal


                                            Example:
                                            
                                            Device# configure terminal
                                            
                                            
                                             

                                            Enters the global configuration mode.

                                             
                                            Step 3ip igmp snooping last-member-query-count count


                                            Example:
                                            
                                            Device(config)# ip igmp snooping last-member-query-count 3
                                            
                                            
                                             

                                            Configures the IGMP last member query count. The range is 1 to 7 messages. The default is 2 messages.

                                             
                                            Step 4ip igmp snooping vlan vlan-id last-member-query-count count


                                            Example:
                                            
                                            Device(config)#ip igmp snooping vlan 100 last-member-query-count 3
                                            
                                            
                                             

                                            (Optional) Configures the IGMP last member query count on the VLAN interface. The range is 1 to 7 messages.

                                            Note   

                                            Configuring the last member query count on a VLAN overrides the globally configured timer.

                                             
                                            Step 5end


                                            Example:
                                            
                                            Device(config)# end
                                            
                                            
                                             

                                            Returns to privileged EXEC mode.

                                             
                                            Step 6show ip igmp snooping


                                            Example:
                                            
                                            Device# show ip igmp snooping
                                            
                                            
                                             

                                            (Optional) Displays the configured IGMP last member query count.

                                             
                                            Step 7copy running-config startup-config


                                            Example:
                                            
                                            Device# copy running-config startup-config
                                            
                                            
                                             

                                            (Optional) Saves your entries in the configuration file.

                                             

                                            Configuring TCN-Related Commands

                                            Controlling the Multicast Flooding Time After a TCN Event (CLI)

                                            You can control the time that multicast traffic is flooded after a topology change notification (TCN) event by using the ip igmp snooping tcn flood query count global configuration command. This command configures the number of general queries for which multicast data traffic is flooded after a TCN event. Some examples of TCN events are when the client changed its location and the receiver is on same port that was blocked but is now forwarding, and when a port went down without sending a leave message.

                                            If you set the TCN flood query count to 1 by using the ip igmp snooping tcn flood query count command, the flooding stops after receiving 1 general query. If you set the count to 7, the flooding continues until 7 general queries are received. Groups are relearned based on the general queries received during the TCN event.

                                            SUMMARY STEPS

                                              1.    enable

                                              2.    configure terminal

                                              3.    ip igmp snooping tcn flood query count count

                                              4.    end

                                              5.    show ip igmp snooping

                                              6.    copy running-config startup-config


                                            DETAILED STEPS
                                               Command or ActionPurpose
                                              Step 1 enable


                                              Example:
                                              Device> enable
                                              
                                              
                                               

                                              Enables privileged EXEC mode.

                                              • Enter your password if prompted.

                                               

                                              Step 2configure terminal


                                              Example:
                                              
                                              Device# configure terminal
                                              
                                              
                                               

                                              Enters the global configuration mode.

                                               
                                              Step 3ip igmp snooping tcn flood query count count


                                              Example:
                                              
                                              Device(config)# ip igmp snooping tcn flood query count 3
                                              
                                              
                                               

                                              Specifies the number of IGMP general queries for which the multicast traffic is flooded. The range is 1 to 10. By default, the flooding query count is 2.

                                              Note   

                                              To return to the default flooding query count, use the no ip igmp snooping tcn flood query count global configuration command.

                                               
                                              Step 4end


                                              Example:
                                              
                                              Device(config)# end
                                              
                                              
                                               

                                              Returns to privileged EXEC mode.

                                               
                                              Step 5show ip igmp snooping


                                              Example:
                                              
                                              Device# show ip igmp snooping
                                              
                                              
                                               

                                              Verifies the TCN settings.

                                               
                                              Step 6copy running-config startup-config


                                              Example:
                                              
                                              Device# copy running-config startup-config
                                              
                                              
                                               

                                              (Optional) Saves your entries in the configuration file.

                                               

                                              Recovering from Flood Mode (CLI)

                                              When a topology change occurs, the spanning-tree root sends a special IGMP leave message (also known as global leave) with the group multicast address 0.0.0.0. However, when you enable the ip igmp snooping tcn query solicit global configuration command, the device sends the global leave message whether or not it is the spanning-tree root. When the router receives this special leave, it immediately sends general queries, which expedite the process of recovering from the flood mode during the TCN event. Leaves are always sent if the device is the spanning-tree root regardless of this configuration command. By default, query solicitation is disabled.

                                              SUMMARY STEPS

                                                1.    enable

                                                2.    configure terminal

                                                3.    ip igmp snooping tcn query solicit

                                                4.    end

                                                5.    show ip igmp snooping

                                                6.    copy running-config startup-config


                                              DETAILED STEPS
                                                 Command or ActionPurpose
                                                Step 1 enable


                                                Example:
                                                Device> enable
                                                
                                                
                                                 

                                                Enables privileged EXEC mode.

                                                • Enter your password if prompted.

                                                 

                                                Step 2configure terminal


                                                Example:
                                                
                                                Device# configure terminal
                                                
                                                
                                                 

                                                Enters the global configuration mode.

                                                 
                                                Step 3ip igmp snooping tcn query solicit


                                                Example:
                                                
                                                Device(config)# ip igmp snooping tcn query solicit
                                                
                                                
                                                 

                                                Sends an IGMP leave message (global leave) to speed the process of recovering from the flood mode caused during a TCN event. By default, query solicitation is disabled.

                                                Note   

                                                To return to the default query solicitation, use the no ip igmp snooping tcn query solicit global configuration command.

                                                 
                                                Step 4end


                                                Example:
                                                
                                                Device(config)# end
                                                
                                                
                                                 

                                                Returns to privileged EXEC mode.

                                                 
                                                Step 5show ip igmp snooping


                                                Example:
                                                
                                                Device# show ip igmp snooping
                                                
                                                
                                                 

                                                Verifies the TCN settings.

                                                 
                                                Step 6copy running-config startup-config


                                                Example:
                                                
                                                Device# copy running-config startup-config
                                                
                                                
                                                 

                                                (Optional) Saves your entries in the configuration file.

                                                 

                                                Disabling Multicast Flooding During a TCN Event (CLI)

                                                When the device receives a TCN, multicast traffic is flooded to all the ports until 2 general queries are received. If the device has many ports with attached hosts that are subscribed to different multicast groups, this flooding might exceed the capacity of the link and cause packet loss. You can use the ip igmp snooping tcn flood interface configuration command to control this operation function.

                                                SUMMARY STEPS

                                                  1.    enable

                                                  2.    configure terminal

                                                  3.    interface interface-id

                                                  4.    no ip igmp snooping tcn flood

                                                  5.    end

                                                  6.    show ip igmp snooping

                                                  7.    copy running-config startup-config


                                                DETAILED STEPS
                                                   Command or ActionPurpose
                                                  Step 1 enable


                                                  Example:
                                                  Device> enable
                                                  
                                                  
                                                   

                                                  Enables privileged EXEC mode.

                                                  • Enter your password if prompted.

                                                   

                                                  Step 2configure terminal


                                                  Example:
                                                  
                                                  Device# configure terminal
                                                  
                                                  
                                                   

                                                  Enters the global configuration mode.

                                                   
                                                  Step 3interface interface-id


                                                  Example:
                                                  
                                                  Device(config)# interface gigabitethernet 1/0/1
                                                  
                                                  
                                                   

                                                  Specifies the interface to be configured, and enters interface configuration mode.

                                                   
                                                  Step 4no ip igmp snooping tcn flood


                                                  Example:
                                                  
                                                  Device(config-if)# no ip igmp snooping tcn flood
                                                  
                                                  
                                                   

                                                  Disables the flooding of multicast traffic during a spanning-tree TCN event.

                                                  By default, multicast flooding is enabled on an interface.

                                                  Note   

                                                  To re-enable multicast flooding on an interface, use the ip igmp snooping tcn flood interface configuration command.

                                                   
                                                  Step 5end


                                                  Example:
                                                  
                                                  Device(config)# end
                                                  
                                                  
                                                   

                                                  Returns to privileged EXEC mode.

                                                   
                                                  Step 6show ip igmp snooping


                                                  Example:
                                                  
                                                  Device# show ip igmp snooping
                                                  
                                                  
                                                   

                                                  Verifies the TCN settings.

                                                   
                                                  Step 7copy running-config startup-config


                                                  Example:
                                                  
                                                  Device# copy running-config startup-config
                                                  
                                                  
                                                   

                                                  (Optional) Saves your entries in the configuration file.

                                                   

                                                  Configuring the IGMP Snooping Querier (CLI)

                                                  Follow these guidelines when configuring the IGMP snooping querier:

                                                  • Configure the VLAN in global configuration mode.
                                                  • Configure an IP address on the VLAN interface. When enabled, the IGMP snooping querier uses the IP address as the query source address.
                                                  • If there is no IP address configured on the VLAN interface, the IGMP snooping querier tries to use the configured global IP address for the IGMP querier. If there is no global IP address specified, the IGMP querier tries to use the VLAN device virtual interface (SVI) IP address (if one exists). If there is no SVI IP address, the device uses the first available IP address configured on the device. The first IP address available appears in the output of the show ip interface privileged EXEC command. The IGMP snooping querier does not generate an IGMP general query if it cannot find an available IP address on the device.
                                                  • The IGMP snooping querier supports IGMP Versions 1 and 2.
                                                  • When administratively enabled, the IGMP snooping querier moves to the nonquerier state if it detects the presence of a multicast router in the network.
                                                  • When it is administratively enabled, the IGMP snooping querier moves to the operationally disabled state under these conditions:
                                                    • IGMP snooping is disabled in the VLAN.
                                                    • PIM is enabled on the SVI of the corresponding VLAN.
                                                  SUMMARY STEPS

                                                    1.    enable

                                                    2.    configure terminal

                                                    3.    ip igmp snooping querier

                                                    4.    ip igmp snooping querier address ip_address

                                                    5.    ip igmp snooping querier query-interval interval-count

                                                    6.    ip igmp snooping querier tcn query [count count | interval interval]

                                                    7.    ip igmp snooping querier timer expiry timeout

                                                    8.    ip igmp snooping querier version version

                                                    9.    end

                                                    10.    show ip igmp snooping vlan vlan-id

                                                    11.    copy running-config startup-config


                                                  DETAILED STEPS
                                                     Command or ActionPurpose
                                                    Step 1 enable


                                                    Example:
                                                    Device> enable
                                                    
                                                    
                                                     

                                                    Enables privileged EXEC mode.

                                                    • Enter your password if prompted.

                                                     

                                                    Step 2configure terminal


                                                    Example:
                                                    
                                                    Device# configure terminal
                                                    
                                                    
                                                     

                                                    Enters the global configuration mode.

                                                     
                                                    Step 3ip igmp snooping querier


                                                    Example:
                                                    
                                                    Device(config)# ip igmp snooping querier
                                                    
                                                    
                                                     

                                                    Enables the IGMP snooping querier.

                                                     
                                                    Step 4ip igmp snooping querier address ip_address


                                                    Example:
                                                    
                                                    Device(config)# ip igmp snooping querier address 172.16.24.1
                                                    
                                                    
                                                    
                                                     

                                                    (Optional) Specifies an IP address for the IGMP snooping querier. If you do not specify an IP address, the querier tries to use the global IP address configured for the IGMP querier.

                                                    Note   

                                                    The IGMP snooping querier does not generate an IGMP general query if it cannot find an IP address on the device.

                                                     
                                                    Step 5ip igmp snooping querier query-interval interval-count


                                                    Example:
                                                    
                                                    Device(config)# ip igmp snooping querier query-interval 30
                                                    
                                                    
                                                     

                                                    (Optional) Sets the interval between IGMP queriers. The range is 1 to 18000 seconds.

                                                     
                                                    Step 6ip igmp snooping querier tcn query [count count | interval interval]


                                                    Example:
                                                    
                                                    Device(config)# ip igmp snooping querier tcn query interval 20
                                                    
                                                    
                                                     

                                                    (Optional) Sets the time between Topology Change Notification (TCN) queries. The count range is 1 to 10. The interval range is 1 to 255 seconds.

                                                     
                                                    Step 7ip igmp snooping querier timer expiry timeout


                                                    Example:
                                                    
                                                    Device(config)# ip igmp snooping querier timer expiry 180
                                                    
                                                    
                                                     

                                                    (Optional) Sets the length of time until the IGMP querier expires. The range is 60 to 300 seconds.

                                                     
                                                    Step 8ip igmp snooping querier version version


                                                    Example:
                                                    
                                                    Device(config)# ip igmp snooping querier version 2
                                                    
                                                    
                                                     

                                                    (Optional) Selects the IGMP version number that the querier feature uses. Select 1 or 2.

                                                     
                                                    Step 9end


                                                    Example:
                                                    
                                                    Device(config)# end
                                                    
                                                    
                                                     

                                                    Returns to privileged EXEC mode.

                                                     
                                                    Step 10show ip igmp snooping vlan vlan-id


                                                    Example:
                                                    
                                                    Device# show ip igmp snooping vlan 30
                                                    
                                                    
                                                     

                                                    (Optional) Verifies that the IGMP snooping querier is enabled on the VLAN interface. The VLAN ID range is 1 to 1001 and 1006 to 4094.

                                                     
                                                    Step 11copy running-config startup-config


                                                    Example:
                                                    
                                                    Device# copy running-config startup-config
                                                    
                                                    
                                                     

                                                    (Optional) Saves your entries in the configuration file.

                                                     

                                                    Disabling IGMP Report Suppression (CLI)


                                                    Note


                                                    IGMP report suppression is supported only when the multicast query has IGMPv1 and IGMPv2 reports. This feature is not supported when the query includes IGMPv3 reports.


                                                    IGMP report suppression is enabled by default. When it is enabled, the device forwards only one IGMP report per multicast router query. When report suppression is disabled, all IGMP reports are forwarded to the multicast routers.

                                                    SUMMARY STEPS

                                                      1.    enable

                                                      2.    configure terminal

                                                      3.    no ip igmp snooping report-suppression

                                                      4.    end

                                                      5.    show ip igmp snooping

                                                      6.    copy running-config startup-config


                                                    DETAILED STEPS
                                                       Command or ActionPurpose
                                                      Step 1 enable


                                                      Example:
                                                      Device> enable
                                                      
                                                      
                                                       

                                                      Enables privileged EXEC mode.

                                                      • Enter your password if prompted.

                                                       

                                                      Step 2configure terminal


                                                      Example:
                                                      
                                                      Device# configure terminal
                                                      
                                                      
                                                       

                                                      Enters the global configuration mode.

                                                       
                                                      Step 3no ip igmp snooping report-suppression


                                                      Example:
                                                      
                                                      Device(config)# no ip igmp snooping report-suppression 
                                                      
                                                      
                                                       

                                                      Disables IGMP report suppression.

                                                      Note   

                                                      To re-enable IGMP report suppression, use the ip igmp snooping report-suppression global configuration command.

                                                       
                                                      Step 4end


                                                      Example:
                                                      
                                                      Device(config)# end
                                                      
                                                      
                                                       

                                                      Returns to privileged EXEC mode.

                                                       
                                                      Step 5show ip igmp snooping


                                                      Example:
                                                      
                                                      Device# show ip igmp snooping 
                                                      
                                                      
                                                       

                                                      Verifies that IGMP report suppression is disabled.

                                                       
                                                      Step 6copy running-config startup-config


                                                      Example:
                                                      
                                                      Device# copy running-config startup-config 
                                                      
                                                      
                                                       

                                                      (Optional) Saves your entries in the configuration file.

                                                       

                                                      Monitoring IGMP

                                                      You can display specific statistics, such as the contents of IP routing tables, caches, and databases.


                                                      Note


                                                      This release does not support per-route statistics.


                                                      You can display information to learn resource usage and solve network problems. You can also display information about node reachability and discover the routing path that packets of your device are taking through the network.

                                                      You can use any of the privileged EXEC commands in the following table to display various routing statistics.

                                                      Table 7 Commands for Displaying System and Network Statistics

                                                      Command

                                                      Purpose

                                                      ping [group-name | group-address]

                                                      Sends an ICMP Echo Request to a multicast group address.

                                                      show ip igmp filter

                                                      Displays IGMP filter information.

                                                      show ip igmp groups [type-number | detail ]

                                                      Displays the multicast groups that are directly connected to the device and that were learned through IGMP.

                                                      show ip igmp interface [type number]

                                                      Displays multicast-related information about an interface.

                                                      show ip igmp membership [ name/group address | all | tracked ]

                                                      Displays IGMP membership information for forwarding.

                                                      show ip igmp profile [ profile_number]

                                                      Displays IGMP profile information.

                                                      show ip igmp ssm-mapping [ hostname/IP address ]

                                                      Displays IGMP SSM mapping information.

                                                      show ip igmp static-group {class-map [ interface [ type ] ]

                                                      Displays static group information.

                                                      show ip igmp vrf

                                                      Displays the selected VPN routing/forwarding instance by name.

                                                      Displaying IGMP Snooping Information

                                                      You can display IGMP snooping information for dynamically learned and statically configured router ports and VLAN interfaces. You can also display MAC address multicast entries for a VLAN configured for IGMP snooping.

                                                      Table 8 Commands for Displaying IGMP Snooping Information

                                                      Command

                                                      Purpose

                                                      show ip igmp snooping detail

                                                      Displays the operational state information.

                                                      show ip igmp snooping groups [ count | [vlan vlan-id [A.B.C.D | count ] ]

                                                      Displays multicast table information for the device or about a specific parameter:

                                                      • count—Displays the total number of groups.
                                                      • vlan—Displays group information by VLAN ID.

                                                      show ip igmp snooping igmpv2-tracking

                                                      Displays the IGMP snooping tracking.

                                                      Note   

                                                      This command displays group and IP address entries only for wireless multicast IGMP joins and not for wired IGMP joins. Wireless IP multicast must be enabled for this command to display.

                                                      show ip igmp snooping mrouter [vlan vlan-id]

                                                      Displays information on dynamically learned and manually configured multicast router interfaces.

                                                      Note   

                                                      When you enable IGMP snooping, the device automatically learns the interface to which a multicast router is connected. These are dynamically learned interfaces.

                                                      (Optional) Enter vlan vlan-id to display information for a single VLAN.

                                                      show ip igmp snooping querier [ detail | vlan vlan-id]

                                                      Displays information about the IP address and receiving port for the most-recently received IGMP query messages in the VLAN.

                                                      (Optional) Enter detail to display the detailed IGMP querier information in a VLAN.

                                                      (Optional) Enter vlan vlan-id to display information for a single VLAN.

                                                      show ip igmp snooping [vlan vlan-id [ detail ] ]

                                                      Displays the snooping configuration information for all VLANs on the device or for a specified VLAN.

                                                      (Optional) Enter vlan vlan-id to display information for a single VLAN. The VLAN ID range is 1 to 1001 and 1006 to 4094.

                                                      show ip igmp snooping wireless mgid

                                                      Displays wireless-related events.

                                                      Displaying IGMP Filtering and Throttling Configuration

                                                      You can display IGMP profile characteristics, and you can display the IGMP profile and maximum group configuration for all interfaces on the device or for a specified interface. You can also display the IGMP throttling configuration for all interfaces on the device or for a specified interface.

                                                      Table 9 Commands for Displaying IGMP Filtering and Throttling Configuration

                                                      Command

                                                      Purpose

                                                      show ip igmp profile [profile number]

                                                      Displays the specified IGMP profile or all the IGMP profiles defined on the device.

                                                      show running-config [interface interface-id]

                                                      Displays the configuration of the specified interface or the configuration of all interfaces on the device, including (if configured) the maximum number of IGMP groups to which an interface can belong and the IGMP profile applied to the interface.

                                                      Configuration Examples for IGMP

                                                      Example: Configuring the Device as a Member of a Multicast Group

                                                      This example shows how to enable the device to join multicast group 255.2.2.2:

                                                      
                                                      Device(config)# interface gigabitethernet1/0/1
                                                      Device(config-if)# ip igmp join-group 255.2.2.2
                                                      Device(config-if)#
                                                      
                                                      

                                                      Example: Controlling Access to Multicast Groups

                                                      To limit the number of joins on the interface, configure the port for filter which associates with the IGMP profile.

                                                      
                                                      Device# configure terminal
                                                      Device(config)# ip igmp profile 10
                                                      Device(config-igmp-profile)# ?
                                                      
                                                      IGMP profile configuration commands:
                                                      deny matching addresses are denied
                                                      exit Exit from igmp profile configuration mode
                                                      no Negate a command or set its defaults
                                                      permit matching addresses are permitted
                                                      range add a range to the set
                                                      
                                                      Device(config-igmp-profile)# range 172.16.5.1
                                                      Device(config-igmp-profile)# exit
                                                      Device(config)#
                                                      Device(config)# interface gigabitEthernet 2/0/10
                                                      Device(config-if)# ip igmp filter 10
                                                      
                                                      

                                                      Examples: Configuring IGMP Snooping

                                                      This example shows how to enable a static connection to a multicast router:

                                                      
                                                      Device# configure terminal
                                                      Device(config)# ip igmp snooping vlan 200 mrouter interface gigabitethernet1/0/2
                                                      Device(config)# end
                                                      
                                                      

                                                      This example shows how to statically configure a host on a port:

                                                      
                                                      Device# configure terminal
                                                      Device(config)# ip igmp snooping vlan 105 static 224.2.4.12 interface gigabitethernet1/0/1
                                                      Device(config)# end
                                                      
                                                      

                                                      This example shows how to enable IGMP Immediate Leave on VLAN 130:

                                                      
                                                      Device# configure terminal
                                                      Device(config)# ip igmp snooping vlan 130 immediate-leave
                                                      Device(config)# end
                                                      
                                                      

                                                      This example shows how to set the IGMP snooping querier source address to 10.0.0.64:

                                                      
                                                      Device# configure terminal
                                                      Device(config)# ip igmp snooping querier 10.0.0.64
                                                      Device(config)# end
                                                      
                                                      

                                                      This example shows how to set the IGMP snooping querier maximum response time to 25 seconds:

                                                      
                                                      Device# configure terminal
                                                      Device(config)# ip igmp snooping querier query-interval 25
                                                      Device(config)# end
                                                      
                                                      

                                                      This example shows how to set the IGMP snooping querier timeout to 60 seconds:

                                                      
                                                      Device# configure terminal
                                                      Device(config)# ip igmp snooping querier timer expiry 60
                                                      Device(config)# end
                                                      
                                                      

                                                      This example shows how to set the IGMP snooping querier feature to Version 2:

                                                      
                                                      Device# configure terminal
                                                      Device(config)# no ip igmp snooping querier version 2
                                                      Device(config)# end
                                                      
                                                      
                                                      Related Concepts

                                                      Examples: Configuring Filtering and Throttling

                                                      This example shows how to create IGMP profile 4 allowing access to the single IP multicast address and how to verify the configuration. If the action was to deny (the default), it would not appear in the show ip igmp profile output display.

                                                      
                                                      Device(config)# ip igmp profile 4
                                                      Device(config-igmp-profile)# permit
                                                      Device(config-igmp-profile)# range 229.9.9.0
                                                      Device(config-igmp-profile)# end
                                                      Device# show ip igmp profile 4
                                                      IGMP Profile 4
                                                          permit
                                                          range 229.9.9.0 229.9.9.0
                                                      
                                                      

                                                      This example shows how to apply IGMP profile 4 to a port:

                                                      
                                                      Device(config)# interface gigabitethernet1/0/2
                                                      Device(config-if)# ip igmp filter 4
                                                      Device(config-if)# end
                                                      
                                                      

                                                      This example shows how to limit to 25 the number of IGMP groups that a port can join:

                                                      
                                                      Device(config)# interface gigabitethernet1/0/2
                                                      Device(config-if)# ip igmp max-groups 25
                                                      Device(config-if)# end
                                                      
                                                      

                                                      Example: Interface Configuration as a Routed Port

                                                      This example shows how to configure an interface on the device as a routed port. This configuration is required on the interface for several IP multicast routing configuration procedures that require running the no switchport command.

                                                      Device configure terminal
                                                      Device(config)#  interface GigabitEthernet1/0/9
                                                      Device(config-if)# description interface to be use as routed port
                                                      Device(config-if)# no switchport
                                                      Device(config-if)# ip address 20.20.20.1 255.255.255.0
                                                      Device(config-if)# ip pim sparse-dense-mode
                                                      Device(config-if)# ip igmp join-group 224.1.2.3 source 15.15.15.2
                                                      Device(config-if)# end
                                                      Device# configure terminal
                                                      Device# show run interface gigabitEthernet 1/0/9
                                                      
                                                      Current configuration : 166 bytes
                                                      !
                                                      interface GigabitEthernet1/0/9
                                                       no switchport
                                                       ip address 20.20.20.1 255.255.255.0
                                                       ip pim sparse-dense-mode
                                                       ip igmp static-group 224.1.2.3 source 15.15.15.2
                                                      end
                                                      
                                                      

                                                      Example: Interface Configuration as an SVI

                                                      This example shows how to configure an interface on the device as an SVI. This configuration is required on the interface for several IP multicast routing configuration procedures that require running the no switchport command.

                                                      Device(config)# interface vlan 150
                                                      Device(config-if)# ip address 20.20.20.1 255.255.255.0
                                                      Device(config-if)# ip pim sparse-dense-mode
                                                      Device(config-if)# ip igmp join-group 224.1.2.3 source 15.15.15.2
                                                      Device(config-if)# end
                                                      Device# configure terminal
                                                      Device(config)#  ip igmp snooping vlan 20 static 224.1.2.3 
                                                      interface gigabitEthernet 1/0/9
                                                      Device# show run interface vlan 150
                                                      
                                                      Current configuration : 137 bytes
                                                      !
                                                      interface Vlan150
                                                       ip address 20.20.20.1 255.255.255.0
                                                       ip pim sparse-dense-mode
                                                       ip igmp static-group 224.1.2.3 source 15.15.15.2
                                                      end
                                                      
                                                      
                                                      

                                                      Example: Configuring the Device to Forward Multicast Traffic in the Absence of Directly Connected IGMP Hosts

                                                      The following example shows how to configure a device to forward multicast traffic in the absence of directly connected IGMP hosts using the ip igmp join-group command. With this method, the device accepts the multicast packets in addition to forwarding them. Accepting the multicast packets prevents the device from fast switching.

                                                      In this example, Fast Ethernet interface 0/0/0 on the device is configured to join the group 225.2.2.2:

                                                      interface FastEthernet0/0/0
                                                       ip igmp join-group 225.2.2.2 
                                                      

                                                      The following example shows how to configure a device to forward multicast traffic in the absence of directly connected IGMP hosts using the ip igmp static-group command. With this method, the device does not accept the packets itself, but only forwards them. Hence, this method allows fast switching. The outgoing interface appears in the IGMP cache, but the device itself is not a member, as evidenced by lack of an “L” (local) flag in the multicast route entry.

                                                      In this example, static group membership entries for group 225.2.2.2 are configured on Fast Ethernet interface 0/1/0:

                                                      interface FastEthernet0/1/0
                                                       ip igmp static-group 225.2.2.2

                                                      Controlling Access to an SSM Network Using IGMP Extended Access Lists

                                                      This section contains the following configuration examples for controlling access to an SSM network using IGMP extended access lists:


                                                      Note


                                                      Keep in mind that access lists are very flexible: there are many combinations of permit and deny statements one could use in an access list to filter multicast traffic. The examples in this section simply provide a few examples of how it can be done.


                                                      Example: Denying All States for a Group G

                                                      The following example shows how to deny all states for a group G. In this example, Fast Ethernet interface 0/0/0 is configured to filter all sources for SSM group 232.2.2.2 in IGMPv3 reports, which effectively denies this group.

                                                      ip access-list extended test1
                                                       deny igmp any host 232.2.2.2
                                                       permit igmp any any
                                                      !
                                                      interface FastEthernet0/0/0
                                                       ip igmp access-group test1

                                                      Example: Denying All States for a Source S

                                                      The following example shows how to deny all states for a source S. In this example, Gigabit Ethernet interface 1/1/0 is configured to filter all groups for source 10.2.1.32 in IGMPv3 reports, which effectively denies this source.

                                                      ip access-list extended test2
                                                       deny igmp host 10.2.1.32 any
                                                       permit igmp any any
                                                      !
                                                      interface GigabitEthernet1/1/0
                                                       ip igmp access-group test2

                                                      Example: Permitting All States for a Group G

                                                      The following example shows how to permit all states for a group G. In this example, Gigabit Ethernet interface 1/2/0 is configured to accept all sources for SSM group 232.1.1.10 in IGMPv3 reports, which effectively accepts this group altogether.

                                                      ip access-list extended test3
                                                       permit igmp any host 232.1.1.10
                                                      !
                                                      interface GigabitEthernet1/2/0
                                                       ip igmp access-group test3

                                                      Example: Permitting All States for a Source S

                                                      The following example shows how to permit all states for a source S. In this example, Gigabit Ethernet interface 1/2 is configured to accept all groups for source 10.6.23.32 in IGMPv3 reports, which effectively accepts this source altogether.

                                                      ip access-list extended test4
                                                       permit igmp host 10.6.23.32 any
                                                      !
                                                      interface GigabitEthernet1/2/0
                                                       ip igmp access-group test4

                                                      Example: Filtering a Source S for a Group G

                                                      The following example shows how to filter a particular source S for a group G. In this example, Gigabit Ethernet interface 0/3/0 is configured to filter source 232.2.2.2 for SSM group 232.2.30.30 in IGMPv3 reports.

                                                      ip access-list extended test5
                                                       deny igmp host 10.4.4.4 host 232.2.30.30
                                                       permit igmp any any
                                                      !
                                                      interface GigabitEthernet0/3/0
                                                       ip igmp access-group test5

                                                      Where to Go Next for IGMP

                                                      You can configure the following:

                                                      • Wireless Multicast
                                                      • PIM
                                                      • SSM
                                                      • IP Multicast Routing
                                                      • Service Discovery Gateway

                                                      You can also review the following IP Multicast Optimization processes for your configuration:

                                                      • Optimizing PIM Sparse Mode in a Large IP Multicast Deployment
                                                      • Multicast Subsecond Convergence
                                                      • IP Multicast Load Splitting across Equal-Cost Paths
                                                      • SSM Channel Based Filtering for Multicast
                                                      • PIM Dense Mode State Refresh
                                                      • IGMP State Limit

                                                      Additional References

                                                      Related Documents

                                                      Related Topic Document Title

                                                      For complete syntax and usage information for the commands used in this chapter.

                                                      IP Multicast Routing Command Reference (Catalyst 3850 Switches)

                                                      Error Message Decoder

                                                      Description Link

                                                      To help you research and resolve system error messages in this release, use the Error Message Decoder tool.

                                                      https:/​/​www.cisco.com/​cgi-bin/​Support/​Errordecoder/​index.cgi

                                                      Standards and RFCs

                                                      Standard/RFC Title

                                                      RFC 1112

                                                      Host Extensions for IP Multicasting

                                                      RFC 2236

                                                      Internet Group Management Protocol, Version 2

                                                      MIBs

                                                      MIB MIBs Link
                                                      All supported MIBs for this release.

                                                      To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

                                                      http:/​/​www.cisco.com/​go/​mibs

                                                      Technical Assistance

                                                      Description Link

                                                      The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

                                                      To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

                                                      Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

                                                      http:/​/​www.cisco.com/​support

                                                      Feature History and Information for IGMP

                                                      Release

                                                      Modification

                                                      Cisco IOS XE 3.2SE

                                                      This feature was introduced.