Catalyst 6500 Series Software Configuration Guide, 6.3 and 6.4 - Configuring Multicast Services [Cisco Catalyst 6500 Series Switches]

Table Of Contents

Configuring Multicast Services

Understanding How Multicasting Works

Multicasting and Multicast Services Overview

Understanding How IGMP Snooping Works

Joining a Multicast Group

Constraining Multicast Traffic

Leaving a Multicast Group

IGMP Fast-Leave Processing

Understanding How GMRP Works

Understanding How RGMP Works

Suppressing Multicast Traffic

Nonreverse Path Forwarding Multicast Fast Drop

Enabling Installation of Directly Connected Subnets

Configuring IGMP Snooping

Default IGMP Snooping Configuration

Enabling IGMP Snooping

Specifying IGMP Snooping Mode

Enabling IGMP Rate Limiting

Enabling IGMP Fast-Leave Processing

Displaying Multicast Router Information

Displaying Multicast Group Information

Displaying IGMP Snooping Statistics

Disabling IGMP Fast-Leave Processing

Disabling IGMP Snooping

Configuring GMRP

GMRP Software Requirements

Default GMRP Configuration

Enabling GMRP Globally

Enabling GMRP on Individual Switch Ports

Disabling GMRP on Individual Switch Ports

Enabling GMRP Forward-All Option

Disabling GMRP Forward-All Option

Configuring GMRP Registration

Setting Normal Registration

Setting Fixed Registration

Setting Forbidden Registration

Setting the GARP Timers

Displaying GMRP Statistics

Clearing GMRP Statistics

Disabling GMRP Globally on the Switch

Configuring Multicast Router Ports and Group Entries

Specifying Multicast Router Ports

Configuring Multicast Groups

Clearing Multicast Router Ports

Clearing Multicast Group Entries

Configuring RGMP

Configuring RGMP on the Supervisor Engine

Default RGMP Configuration

Enabling and Disabling RGMP

Displaying RGMP Group Information

Displaying RGMP VLAN Statistics

Displaying Ports Connected to RGMP-Capable Routers

Clearing RGMP Statistics

RGMP-Related CLI Commands

Configuring RGMP on the MSFC

Displaying Multicast Protocol Status

Configuring Multicast Services

This chapter describes how to configure Internet Group Management Protocol (IGMP) snooping, GARP Multicast Registration Protocol (GMRP), and Router-Port Group Management Protocol (RGMP) on the Catalyst 6000 family switches.

Note For complete syntax and usage information for the commands used in this chapter, refer to the Catalyst 6000 Family Command Reference publication.

This chapter consists of these sections:

•Understanding How Multicasting Works

•Configuring IGMP Snooping

•Configuring GMRP

•Configuring Multicast Router Ports and Group Entries

•Configuring RGMP

•Displaying Multicast Protocol Status

Understanding How Multicasting Works

These sections describe how multicasting works on the Catalyst 6000 family switches:

•Multicasting and Multicast Services Overview

•Understanding How IGMP Snooping Works

•Understanding How GMRP Works

•Understanding How RGMP Works

•Suppressing Multicast Traffic

•Nonreverse Path Forwarding Multicast Fast Drop

•Enabling Installation of Directly Connected Subnets

Multicasting and Multicast Services Overview

IGMP snooping manages multicast traffic in switches by allowing directed switching of IP multicast traffic. GMRP is protocol independent and can manage both IP multicast traffic and any Layer 2 multicast traffic.

Switches can use IGMP snooping or GMRP to configure switch ports dynamically so that IP multicast traffic is forwarded only to those ports associated with IP multicast hosts. IGMP software components run on both the Cisco router and the switch.

Note For more information on IP multicast and IGMP, refer to RFC 1112. GMRP is described in IEEE 802.1p.

You can statically configure multicast groups using the set cam static command. Multicast groups learned through IGMP snooping are dynamic. If you specify group membership for a multicast group address, your static setting supersedes any automatic manipulation by IGMP snooping or GMRP. Multicast group membership lists can consist of both user-defined setting and setting learned through IGMP snooping or GMRP.

Understanding How IGMP Snooping Works

Note You can run IGMP snooping on any Catalyst 6000 family supervisor engine model (Supervisor Engine 1, Supervisor Engine 1A, and Supervisor Engine 2). A PFC is not required to enable IGMP snooping. Cisco Group Management Protocol (CGMP) is not supported on the Catalyst 6000 family switches, although CGMP server is supported on the MSFC. To support CGMP client devices, configure the MSFC as a CGMP server.

IGMP snooping manages multicast traffic at Layer 2 on the Catalyst 6000 family switches by allowing directed switching of IP multicast traffic.

Switches can use IGMP snooping to configure Layer 2 interfaces dynamically so that IP multicast traffic is forwarded only to those interfaces associated with IP multicast devices.

Catalyst 6000 switches can distinguish IGMP control traffic from multicast data traffic. When IGMP is enabled on the switch, IGMP control traffic is redirected to the CPU for further processing. This process is performed in hardware by specialized ASICs, which allow the switch to snoop IGMP control traffic with no performance penalty.

The route processor periodically sends out general queries to all VLANs, and as multicast receivers respond to the router's queries, the switch intercepts them. Only the first IGMP join (report) per VLAN and per IP multicast group is forwarded to the router. Subsequent reports for the same VLAN and group are suppressed. The switch processor creates one entry per VLAN in the Layer 2 forwarding table for each MAC group from which it receives an IGMP join request. All hosts interested in this multicast traffic send join requests and are added to the port list of this forwarding table entry.

If a port is disabled, it will be removed from all multicast group entries.

Note You cannot enable IGMP snooping on a switch if GMRP is already enabled on the switch.

Joining a Multicast Group

When a host wants to join an IP multicast group, it sends an IGMP join (also known as a join message) specifying the IP multicast group it wants to join (for example, group 224.1.2.3). The switch hardware recognizes that the packet is an IGMP report and redirects it to the switch CPU. The switch installs a new group entry for 01-00-5e-01-02-03 and adds the host port and the router port to that entry. The switch then relays the join from the host to all multicast router ports. The designated multicast router for the segment adds the outgoing interface (OIF) to the outgoing interface list (OIL) for the group and begins forwarding multicast traffic for 224.1.2.3 to this segment.

When a second host in this VLAN wants to join group 244.1.2.3, it sends out an IGMP join for this group. The switch hardware recognizes that this is an IGMP control packet and redirects it to the switch CPU. Since the switch already has a group entry for 01-00-5e-01-02-03 in this VLAN, it just adds the second host port to the entry. Because this is not the first host joining the group, the switch suppresses the report (does not send it to the router).

Constraining Multicast Traffic

When a host sends multicast traffic to a group, the switch hardware does not recognize the stream as IGMP control packets and therefore the packets are not redirected to the switch CPU. Instead the multicast traffic hits the MAC group entry and the switch constrains the traffic to only those ports that have been added to that group entry.

The router sends IGMP general queries every 60 seconds by default. The switch floods these queries on all ports in the VLAN, and hosts that are interested in a multicast group respond with an IGMP join for each group in which they are interested.

The switch intercepts these IGMP joins, and only the first join per VLAN and per IP multicast group is forwarded on the multicast router ports. Subsequent reports for the same VLAN and group are suppressed (not sent to the router).

Note If there are CGMP switches in the network, join and leave suppression does not occur. In a network that has both IGMP and CGMP switches, all join and leave messages are forwarded to the multicast routers so that CGMP join and leave messages can be generated by the router.

Leaving a Multicast Group

The designated multicast router for a segment continues forwarding the multicast traffic to that VLAN as long as at least one host in the VLAN wishes to receive multicast traffic. When hosts want to leave a multicast group, they can either ignore the periodic general queries sent by the multicast router (IGMP v1 host behavior), or they can send an IGMP leave (IGMP v2 host behavior). When the switch receives a leave message, it sends out a MAC-based general query on the port on which it received the leave message to determine if any devices connected to this port are interested in traffic for the specific multicast group. If this port is the last port in the VLAN, the switch sends a MAC-based general query to all ports in the VLAN. MAC-based general queries are addressed to the Layer 2 Group Destination Address (GDA) MAC address for which the IGMP leave message was received. At Layer 3, the MAC-based general queries are addressed to 244.0.0.1 (all hosts), and in the IGMP header, the group address field is set to 0.0.0.0.

If no IGMP join is received for any of the IP multicast groups that map to the MAC multicast group address, the port is removed from the multicast forwarding entry. If the port is not the last non-multicast-router port in the entry, the switch suppresses the IGMP leave (does not send it to the router). If the port is the last non-multicast-router port in the entry, the IGMP leave is forwarded to the multicast router ports and the MAC group forwarding entry is removed.

When the router receives the IGMP leave, it sends several IGMP group-specific queries. If no join messages are received in response to the queries, and there are no downstream routers connected through that interface, the router removes the interface from the OIL for that IP multicast group entry in the multicast routing table.

IGMP Fast-Leave Processing

IGMP snooping fast-leave processing allows the switch processor to remove an interface from the port list of a forwarding-table entry without first sending out a MAC-based general query on the port. When an IGMP leave is received on a port, the port is immediately removed from the multicast forwarding entry (or the entire entry is removed).

Note Do not use the fast-leave processing feature if more than one host is connected to each port. If fast-leave is enabled when more than one host is connected to a port, some hosts might be dropped inadvertently. Fast leave is supported with IGMP version 2 hosts only.

Understanding How GMRP Works

GMRP is a Generic Attribute Registration Protocol (GARP) application that provides a constrained multicast flooding facility similar to IGMP snooping. GMRP and GARP are industry-standard protocols defined by the IEEE. For detailed protocol operational information, refer to 802.1p.

GMRP software components run on both the switch and on the host. (Cisco is not a source for GMRP host software.) On the host, in an IP multicast environment, you must use IGMP with GMRP; the host GMRP software spawns Layer 2 GMRP versions of the host's Layer 3 IGMP control packets. The switch receives both the Layer 2 GMRP and the Layer 3 IGMP traffic from the host. The switch forwards the Layer 3 IGMP control packets to the router and uses the received GMRP traffic to constrain multicasts at Layer 2 in the host's VLAN.

When a host wants to join an IP multicast group, it sends an IGMP join, which spawns a GMRP join. When the switch receives the GMRP join, it adds the port through which the join was received to the appropriate multicast group. The switch propagates the GMRP join to all other hosts in the VLAN, one of which is typically the multicast source. When the source is multicasting to the group, the switch forwards the multicast only to the ports from which it received join messages for the group.

The switch sends periodic GMRP queries. If a host wants to remain in a multicast group, it responds to the query and the switch does nothing. If a host does not want to remain in the multicast group, it can either send a leave message or not respond to the periodic queries from the switch. If the switch receives a leave message or receives no response from the host for the duration of the leaveall timer, the switch removes the host from the multicast group.

Note To use GMRP in a routed environment, enable the GMRP forwardall option on all ports where routers are attached. (See the "Enabling GMRP Forward-All Option" section.)

Understanding How RGMP Works

Without RGMP, all multicast routers receive all multicast data traffic entering the switch. With RGMP, a multicast router can request not to receive multicast traffic if that router has no downstream receivers for the multicast traffic. Catalyst 6000 family switches support RGMP, which enables a switch to reduce network congestion by forwarding multicast data traffic only to those routers that are configured to receive it.

Note To use RGMP, IGMP Snooping must be enabled on the switch. Protocol independent multicast (PIM) must be enabled on all routers for RGMP to work. Only PIM sparse mode is currently supported.

All routers on the network must be RGMP-capable. RGMP-capable routers periodically send an RGMP hello message to the switch. The RGMP hello message tells the switch not to send multicast data to the router unless an RGMP join has also been sent to the switch from that router. When an RGMP join is sent, the router is able to receive multicast data. To learn how to set a router to receive RGMP data, see the "RGMP-Related CLI Commands" section.

To stop receiving multicast data, a router must send an RGMP leave message to the switch. To disable RGMP on a router, the router must send an RGMP bye message to the switch.

Table 40-1 provides a summary of the RGMP packet types.

Table 40-1 RGMP Message Types

Description

Action

Hello

When the RGMP feature is enabled on the router, no multicast data traffic is sent to the router by the switch unless an RGMP join is specifically sent for a group.

Bye

When RGMP feature is disabled on the router, all multicast data traffic will be sent to the router by the switch.

Join

Multicast data traffic for a multicast MAC address from the L3 group address G are sent to the router. These packets will have group G in the Group Address field of the RGMP packet.

Leave

Multicast data traffic for the group G will not be sent to the router. These packets will have group G in the group address field of the RGMP packet.

Suppressing Multicast Traffic

On Gigabit Ethernet ports, you can limit the amount of bandwidth to be used for multicast traffic. Use the set port broadcast command to specify a percentage of the total bandwidth to be used for multicast traffic on Gigabit Ethernet ports.

Nonreverse Path Forwarding Multicast Fast Drop

In a redundant configuration where multiple routers connect to the same LAN segment, only one router forwards the multicast traffic from the source to the receivers on the outgoing interfaces. In this kind of topology, only the Protocol Independent Multicast designated forwarder (PIM-DF) forwards the data in the common VLAN, but the non-PIM-DF receives the forwarded multicast traffic. The redundant router (non-PIM-DF) must drop this traffic because it has arrived on the wrong interface and will fail the reverse path forwarding (RPF) check. Traffic that fails the RPF check is called non-RPF traffic.

Non-RPF multicast fast drop (MFD) rate limits packets that fail the RPF check (non-RPF packets) and drops the majority of the non-RPF packets in hardware. According to the multicast protocol specification, the router needs to see the non-RPF packets for the PIM assert mechanism to work, so all non-RPF packets cannot be dropped in hardware. To support the PIM assert mechanism, the PFC leaks a percentage of the non-RFP flow packets to the MSFC.

Non-RPF MFD is enabled on the switch by default. Non-RPF MFD is supported with Supervisor Engine 2 only.

Enabling Installation of Directly Connected Subnets

In PIM sparse mode, a first-hop router that is the designated router (DR) for the interface may need to encapsulate the source traffic in a PIM register message and unicast it to the rendezvous point (RP). To prevent new sources for the group from being learned in the routing table, the (*,G) flows should remain completely hardware-switched flows. (subnet/mask, 224/4) entries installed in the hardware FIB allow both (*,G) flows to remain completely hardware-switched flows, and new, directly connected sources to be learned correctly. Installation of directly connected subnets is enabled globally by default. One (subnet/mask, 224/4) is installed per PIM-enabled interface.

Use the show mls ip multicast connected command to view such FIB entries.

To enable installation of directly connected subnets, perform this task:

Task

Command

Enable downloading of directly connected subnets.

Router(config) # mls ip multicast connected

This example shows how to install directly connected subnets:
Router(config)# mls ip multicast connected
Router(config)#
Configuring IGMP Snooping

IGMP snooping allows switches to examine IGMP packets and make forwarding decisions based on their content.

Note Quality of service (QoS) does not support IGMP traffic when IGMP snooping is enabled.

These sections describe how to configure IGMP snooping:

•Default IGMP Snooping Configuration

•Enabling IGMP Snooping

•Specifying IGMP Snooping Mode

•Enabling IGMP Fast-Leave Processing

•Enabling IGMP Rate Limiting

•Displaying Multicast Router Information

•Displaying Multicast Group Information

•Displaying IGMP Snooping Statistics

•Disabling IGMP Fast-Leave Processing

•Disabling IGMP Snooping

Default IGMP Snooping Configuration

Table 40-2 shows the default IGMP snooping configuration.

Note IGMP snooping is enabled by default in supervisor engine software release 5.5(9) and later releases and 6.3(1) and later releases.

Table 40-2 IGMP Snooping Default Configuration

Feature

Default Value

IGMP snooping

Disabled

Multicast routers

None configured

Enabling IGMP Snooping

Note You cannot enable IGMP snooping if GMRP is enabled.

To enable IGMP snooping, perform this task in privileged mode:

Task

Command

Step 1

Enable IGMP snooping on the switch.

set igmp enable

Step 2

Verify that IGMP snooping is enabled.

show igmp statistics [vlan]

This example shows how to enable IGMP snooping and verify the configuration:
Console> (enable) set igmp enable
IGMP Snooping is enabled.
Console> (enable) show igmp statistics
IGMP enabled
IGMP statistics for vlan 1:
Total valid pkts rcvd:           18951
Total invalid pkts recvd         0
General Queries recvd            377
Group Specific Queries recvd     0
MAC-Based General Queries recvd  0
Leaves recvd                     14
Reports recvd                    16741
Queries  Xmitted                 0
GS Queries Xmitted               16
Reports Xmitted                  0
Leaves Xmitted                   0
Failures to add GDA to EARL      0
Topology Notifications rcvd      10
IGMP packets dropped             0
Console> (enable)
Specifying IGMP Snooping Mode

IGMP snooping runs in teither IGMP-only mode or IGMP-CGMP mode. The switch dynamically chooses either IGMP-only or IGMP-CGMP mode, depending on the traffic present on the network. IGMP-only mode is used in networks with no CGMP devices. IGMP-CGMP mode is used in networks with both IGMP and CGMP devices. Auto mode overrides the dynamic switching of the modes.

To specify the IGMP snooping mode, perform this task in privileged mode:

Task

Command

Step 1

Specifies the IGMP snooping mode.

set igmp mode {igmp-only | igmp-cgmp | auto}

Step 2

Displays the IGMP snooping mode.

show igmp mode

This example shows how to set the IGMP mode to IGMP-only and verify the configuration:
Console> (enable) set igmp mode igmp-only 
IGMP mode set to igmp-only 
Console> (enable) show igmp mode
IGMP Mode:                  igmp-only
IGMP Operational Mode:      igmp-only
IGMP Address Aliasing Mode: normal
Console> (enable)
Enabling IGMP Rate Limiting

IGMP rate limiting is disabled by default and the default rate limit is 100 packets per 30 seconds for all packet types. Valid rate-limit values are from 1 to 65535 packets per 30 seconds.

Note If IGMP rate limiting and multicast are enabled, multicast router ports might age out sporadically because the rate of the multicast control packets (such as PIMv2 hellos or IGMP general queries) exceeds the IGMP rate limit watermarks that were configured. The default value for these watermarks is 100. We recommend that you increase the PIMv2 hello ratelimit to 3000 by entering the set igmp ratelimit pimv2 3000 command. You can also increase the IGMP general queries rate limit; we recommend that you set the value to 500 by entering the set igmp ratelimit general-query 500 command.

To enable IGMP rate limiting and set the rate limit for IGMP snooping packets, perform this task in privileged mode:

Task

Command

Enable IGMP rate limiting and set a rate limit for IGMP snooping packets.

set igmp ratelimit {enable | disable}

set igmp ratelimit {dvmrp | general-query | mospf1 | mospf2 | pimv2} rate

This example shows how to enable IGMP rate limiting:
Console> (enable) set igmp ratelimit enable
IGMP Ratelimiting enabled
Console> (enable)
This example shows how to set the IGMP rate limit for MOSPF2 to 550 packets per every 30 seconds:
Console> (enable) set igmp ratelimit mospf2 550
MOSPF2 Watermark set to allow 550 messages in 30 seconds
Console> (enable)
Enabling IGMP Fast-Leave Processing

To enable IGMP fast-leave processing, perform this task in privileged mode:

Task

Command

Step 1

Enable IGMP fast-leave processing on the switch.

set igmp fastleave enable

Step 2

Verify that IGMP fast-leave processing is enabled.

show igmp statistics

This example shows how to enable IGMP fast-leave processing and verify the configuration:
Console> (enable) set igmp fastleave enable
IGMP fastleave set to enable.
Console> (enable) show igmp statistics
IGMP enabled
IGMP fastleave enabled
IGMP statistics for vlan 1:
Total valid pkts rcvd:           18951
Total invalid pkts recvd         0
General Queries recvd            377
Group Specific Queries recvd     0
MAC-Based General Queries recvd  0
Leaves recvd                     14
Reports recvd                    16741
Other Pkts recvd                 0
Queries  Xmitted                 0
GS Queries Xmitted               16
Reports Xmitted                  0
Leaves Xmitted                   0
Failures to add GDA to EARL      0
Topology Notifications rcvd      10
Console> (enable) 
Displaying Multicast Router Information

When you enable IGMP snooping, the switch automatically learns to which ports a multicast router is connected.

To display the dynamically learned multicast router information, perform these tasks in privileged mode:

Task

Command

Display information on dynamically learned and manually configured multicast router ports.

show multicast router [mod/port] [vlan_id]

Display information only on those multicast router ports learned dynamically using IGMP snooping.

show multicast router igmp [mod/port] [vlan_id]

This example shows how to display information on all multicast router ports (the asterisk [*] next to the multicast router on port 5/7 indicates that the entry was configured manually):
Console> (enable) show multicast router
IGMP enabled
Port       Vlan
---------  ----------------
 1/1       1
 2/1       2,99,255
 5/7    *  99
Total Number of Entries = 3
'*' - Configured
Console> (enable)
This example shows how to display only those multicast router ports that were learned dynamically through IGMP:
Console> (enable) show multicast router igmp
IGMP enabled
Port       Vlan
---------  ----------------
 1/1       1
 2/1       2,99,255
Total Number of Entries = 2
'*' - Configured
Console> (enable)
Displaying Multicast Group Information

To display information about multicast groups, perform these tasks in privileged mode:

Task

Command

Display information about multicast groups.

show multicast group [mac_addr] [vlan_id]

Display only information about multicast groups learned dynamically through IGMP.

show multicast group igmp [mac_addr] [vlan_id]

Display the total number of multicast addresses (groups) in each VLAN.

show multicast group count [vlan_id]

Display the total number of multicast addresses (groups) in each VLAN that were learned dynamically through IGMP.

show multicast group count igmp [vlan_id]

This example shows how to display information about all multicast groups on the switch:
Console> (enable) show multicast group
IGMP enabled
VLAN  Dest MAC/Route Des  Destination Ports or VCs / [Protocol Type]
----  ------------------  ----------------------------------------------------
1     01-00-11-22-33-44*  2/6-12
1     01-11-22-33-44-55*  2/6-12
1     01-22-33-44-55-66*  2/6-12
1     01-33-44-55-66-77*  2/6-12
Total Number of Entries = 4
Console> (enable)
Displaying IGMP Snooping Statistics

To display IGMP snooping statistics on the switch, perform this task:

Task

Command

Display IGMP snooping statistics.

show igmp statistics [vlan_id]

This example shows how to display IGMP snooping statistics:
Console> (enable) show igmp statistics
IGMP enabled
IGMP statistics for vlan 1:
Total valid pkts rcvd:           18951
Total invalid pkts recvd         0
General Queries recvd            377
Group Specific Queries recvd     0
MAC-Based General Queries recvd  0
Leaves recvd                     14
Reports recvd                    16741
Queries  Xmitted                 0
GS Queries Xmitted               16
Reports Xmitted                  0
Leaves Xmitted                   0
Failures to add GDA to EARL      0
Topology Notifications rcvd      10
IGMP packets dropped             0
Console> (enable)
Disabling IGMP Fast-Leave Processing

To disable IGMP fast-leave processing, perform this task in privileged mode:

Task

Command

Disable IGMP fast-leave processing on the switch.

set igmp fastleave disable

This example shows how to disable IGMP fast-leave processing on the switch:
Console> (enable) set igmp fastleave disable
IGMP fastleave set to disable.
Console> (enable) 
Disabling IGMP Snooping

To disable IGMP snooping on the switch, perform this task in privileged mode:

Task

Command

Disable IGMP snooping on the switch.

set igmp disable

This example shows how to disable IGMP snooping:
Console> (enable) set igmp disable
IGMP feature for IP multicast disabled
Console> (enable)
Configuring GMRP

These sections describe how to configure the GARP Multicast Registration Protocol (GMRP):

•GMRP Software Requirements

•Default GMRP Configuration

•Enabling GMRP Globally

•Enabling GMRP on Individual Switch Ports

•Disabling GMRP on Individual Switch Ports

•Enabling GMRP Forward-All Option

•Disabling GMRP Forward-All Option

•Configuring GMRP Registration

•Setting the GARP Timers

•Displaying GMRP Statistics

•Clearing GMRP Statistics

•Disabling GMRP Globally on the Switch

Note For an overview of GMRP operation, see the "Understanding How GMRP Works" section.

GMRP Software Requirements

GMRP requires supervisor engine software release 5.2 or later releases.

Default GMRP Configuration

Table 40-3 shows the default GMRP configuration.

Table 40-3 GMRP Default Configuration

Feature

Default Value

GMRP enable state

Disabled

GMRP per-port enable state

Disabled

GMRP forward all

Disabled on all ports

GMRP registration

Normal on all ports

GARP/GMRP timers

•Join time: 200 ms

•Leave time: 600 ms

•Leaveall time: 10,000 ms

Enabling GMRP Globally

Note You cannot enable GMRP if IGMP snooping is enabled.

To enable GMRP globally, perform this task in privileged mode:

Task

Command

Step 1

Enable GMRP globally on the switch.

set gmrp enable

Step 2

Verify the configuration.

show gmrp configuration

This example shows how to enable GMRP globally and verify the configuration:
Console> (enable) set gmrp enable
GMRP enabled.
Console> (enable) show gmrp configuration
Global GMRP Configuration:
GMRP Feature is currently enabled on this switch.
GMRP Timers (milliseconds):
Join = 200
Leave = 600
LeaveAll = 10000
Port based GMRP Configuration:
Port                                         GMRP Status Registration ForwardAll
-------------------------------------------- ----------- ------------ ----------
1/1-2,3/1,6/1-48,7/1-24                      Enabled     Normal       Disabled  
Console> (enable)
Enabling GMRP on Individual Switch Ports

Note You can change the per-port GMRP configuration regardless of whether GMRP is enabled globally. However, GMRP will not function on any ports until you enable it globally. For information on configuring GMRP globally on the switch, see the "Enabling GMRP Globally" section.

To enable GMRP on individual switch ports, perform this task in privileged mode:

Task

Command

Step 1

Enable GMRP on an individual switch port.

set port gmrp enable mod/port

Step 2

Verify the configuration.

show gmrp configuration

This example shows how to enable GMRP on port 6/12 and verify the configuration:
Console> (enable) set port gmrp enable 6/12    
GMRP enabled on port 6/12.
Console> (enable) show gmrp configuration
Global GMRP Configuration:
GMRP Feature is currently enabled on this switch.
GMRP Timers (milliseconds):
Join = 200
Leave = 600
LeaveAll = 10000
Port based GMRP Configuration:
Port                                         GMRP Status Registration ForwardAll
-------------------------------------------- ----------- ------------ ----------
1/1-2,3/1,6/1-9,6/12,6/15-48,7/1-24          Enabled     Normal       Disabled  
6/10-11,6/13-14                              Disabled    Normal       Disabled  
Console> (enable)
Disabling GMRP on Individual Switch Ports

Note You can change the per-port GMRP configuration regardless of whether GMRP is enabled globally. However, GMRP will not function on any ports until you enable it globally. For information on configuring GMRP globally on the switch, see the "Enabling GMRP Globally" section.

To disable GMRP on individual switch ports, perform this task in privileged mode:

Task

Command

Step 1

Disable GMRP on individual switch ports.

set port gmrp disable mod/port

Step 2

Verify the configuration.

show gmrp configuration

This example shows how to disable GMRP on ports 6/10-14 and verify the configuration:
Console> (enable) set port gmrp disable 6/10-14
GMRP disabled on ports 6/10-14.
Console> (enable) show gmrp configuration
Global GMRP Configuration:
GMRP Feature is currently enabled on this switch.
GMRP Timers (milliseconds):
Join = 200
Leave = 600
LeaveAll = 10000
Port based GMRP Configuration:
Port                                         GMRP Status Registration ForwardAll
-------------------------------------------- ----------- ------------ ----------
1/1-2,3/1,6/1-9,6/15-48,7/1-24               Enabled     Normal       Disabled  
6/10-14                                      Disabled    Normal       Disabled  
Console> (enable) 
Enabling GMRP Forward-All Option

When you enable the GMRP forward-all option on a port, a copy of all multicast traffic registered on the switch is forwarded to that port. Enable the forward-all option on any port connected to a router that needs to receive any multicasts (routers do not support GMRP and so cannot send GMRP join mesages). The forward-all option can also be used to forward all registered multicast traffic to a port with a network analyzer or probe attached.

To enable the GMRP forward-all option on a switch port, perform this task in privileged mode:

Task

Command

Enable the GMRP forward-all option on a switch port.

set gmrp fwdall enable mod/port

This example shows how to enable the GMRP forward-all option on port 1/1:
Console> (enable) set gmrp fwdall enable 1/1
GMRP Forward All groups option enabled on port 1/1.
Console> (enable) 
Disabling GMRP Forward-All Option

To disable the GMRP forward-all option on a port, perform this task in privileged mode:

Task

Command

Disable the GMRP forward-all option on a port.

set gmrp fwdall disable mod/port

This example shows how to disable the GMRP forward-all option on port 1/1:
Console> (enable) set gmrp fwdall disable 1/1
GMRP Forward All groups option disabled on port 1/1.
Console> (enable) 
Configuring GMRP Registration

These sections describe how to configure GMRP registration modes on switch ports:

•Setting Normal Registration

•Setting Fixed Registration

•Setting Forbidden Registration

Setting Normal Registration

Configuring a port in normal registration mode allows dynamic GMRP multicast registration and deregistration on the port. Normal mode is the default on all switch ports.

To set normal registration on a port, perform this task in privileged mode:

Task

Command

Step 1

Set normal registration on a port.

set gmrp registration normal mod/port

Step 2

Verify the configuration.

show gmrp configuration

This example shows how to set normal registration on port 2/10:
Console> (enable) set gmrp registration normal 2/10
GMRP Registration is set normal on port 2/10.
Console> (enable)
Setting Fixed Registration

When you configure a port in fixed registration mode, all the multicast groups currently registered on all ports are registered on the port, but the port ignores any subsequent registrations or deregistrations on other ports. A port in fixed registration mode continues to register multicast groups that are specific to the port. You must return the port to normal registration mode to deregister multicast groups on the port.

To set fixed registration on a port, perform this task in privileged mode:

Task

Command

Step 1

Set fixed registration on a port.

set gmrp registration fixed mod/port

Step 2

Verify the configuration.

show gmrp configuration

This example shows how to set fixed registration on port 2/10 and verify the configuration:
Console> (enable) set gmrp registration fixed 2/10 
GMRP Registration is set fixed on port 2/10.
Console> (enable) show gmrp configuration
Global GMRP Configuration:
GMRP Feature is currently enabled on this switch.
GMRP Timers (milliseconds):
Join = 200
Leave = 600
LeaveAll = 10000
Port based GMRP Configuration:
GMRP-Status Registration ForwardAll Port(s)
----------- ------------ ---------- --------------------------------------------
Enabled     Normal       Disabled   1/1-4
                                    2/1-9,2/11-48
                                    3/1-24
                                    5/1
Enabled     Fixed        Disabled   2/10
Console> (enable) 
Setting Forbidden Registration

Setting a port in forbidden registration mode deregisters all GMRP multicasts and prevents any further GMRP multicast registration on the port.

To set forbidden registration on a port, perform this task in privileged mode:

Task

Command

Step 1

Set forbidden registration on a port.

set gmrp registration forbidden mod/port

Step 2

Verify the configuration.

show gmrp configuration

This example shows how to set forbidden registration on port 2/10 and verify the configuration:
Console> (enable) set gmrp registration forbidden 2/10
GMRP Registration is set forbidden on port 2/10.
Console> (enable) show gmrp configuration
Global GMRP Configuration:
GMRP Feature is currently enabled on this switch.
GMRP Timers (milliseconds):
Join = 200
Leave = 600
LeaveAll = 10000
Port based GMRP Configuration:
GMRP-Status Registration ForwardAll Port(s)
----------- ------------ ---------- --------------------------------------------
Enabled     Normal       Disabled   1/1-4
                                    2/1-9,2/11-48
                                    3/1-24
                                    5/1
Enabled     Forbidden    Disabled   2/10
Console> (enable) 
Setting the GARP Timers

Note The commands set gmrp timer and show gmrp timer are aliases for set garp timer and show garp timer. The aliases may be used if desired.

Note Modifying the GARP timer values affects the behavior of all GARP applications running on the switch, not just GMRP. (For example, GVRP uses the same timers.)

Note The only ports that send out the GMRP LeaveAll messages are the ports that have previously received GMRP joins.

You can modify the default GARP timer values on the switch.

When setting the timer values, the value for leave must be equal to or greater than three times the join value (leave >= join * 3). The value for leaveall must be greater than the value for leave (leaveall > leave). The more registered attributes on the switch, the greater you should configure the difference between the leave value and the join value.

For better performance on switches with many registered multicast groups, increase the timer values to the order of seconds.

If you attempt to set a timer value that does not adhere to these rules, an error is returned. For example, if you set the leave timer to 600 ms and you attempt to configure the join timer to 350 ms, an error is returned. Set the leave timer to at least 1050 ms and then set the join timer to 350 ms.

Caution Set the same GARP timer values on all Layer 2-connected devices. If the GARP timers are set differently on the Layer 2-connected devices, GARP applications (for example, GMRP and GVRP) do not operate successfully.

To set the GARP timer values, perform this task in privileged mode:

Task

Command

Step 1

Set the GARP timer values.

set garp timer {join | leave | leaveall} timer_value

Step 2

Verify the configuration.

show garp timer

This example shows how to set the GARP timers and verify the configuration:
Console> (enable) set garp timer leaveall 12000
GMRP/GARP leaveAll timer value is set to 12000 milliseconds.
Console> (enable) set garp timer leave 650
GMRP/GARP leave timer value is set to 650 milliseconds.
Console> (enable) set garp timer join 300
GMRP/GARP join timer value is set to 300 milliseconds.
Console> (enable) show garp timer
Timer     Timer Value (milliseconds)
--------  --------------------------
Join      300                       
Leave     650                       
LeaveAll  12000                    
Console> (enable)
Displaying GMRP Statistics

To display GMRP statistics on the switch, perform this task in privileged mode:

Task

Command

Display GMRP statistics.

show gmrp statistics [vlan_id]

This example shows how to display GMRP statistics for VLAN 23:
Console> show gmrp statistics 23
GMRP Statistics for vlan <23>:
Total valid GMRP Packets Received:500
Join Empties:200
Join INs:250
Leaves:10
Leave Alls:35
Empties:5
Fwd Alls:0
Fwd Unregistered:0
Total valid GMRP Packets Transmitted:600
Join Empties:200
Join INs:150
Leaves:45
Leave Alls:200
Empties:5
Fwd Alls:0
Fwd Unregistered:0
Total valid GMRP Packets Received:0
Total GMRP packets dropped:0
Total GMRP Registrations Failed:0
Console>
Clearing GMRP Statistics

To clear all GMRP statistics on the switch, perform this task in privileged mode:

Task

Command

Clear GMRP statistics.

clear gmrp statistics {vlan_id | all}

This example shows how to clear the GMRP statistics for all VLANs:
Console> (enable) clear gmrp statistics all
Console> (enable)
Disabling GMRP Globally on the Switch

To disable GMRP globally on the switch, perform this task in privileged mode:

Task

Command

Disable GMRP globally on the switch.

set gmrp disable

This example shows how to disable GMRP globally on the switch:
Console> (enable) set gmrp disable
GMRP disabled.
Console> (enable)
Configuring Multicast Router Ports and Group Entries

These sections describe how to specify multicast router ports manually and configure multicast group entries:

•Specifying Multicast Router Ports

•Configuring Multicast Groups

•