Consolidated Platform Configuration Guide, Cisco IOS XE 3.3SE (Catalyst 3850 Switches)
Configuring PIM
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Contents

Configuring PIM

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.

Prerequisites for Configuring PIM

The following are the prerequisites for configuring PIM and PIM stub routing:

  • Before configuring PIM stub routing, you must have IP multicast routing configured on both the stub router and the central router. You must also have PIM mode (dense-mode, sparse-mode, or sparse-dense-mode) configured on the uplink interface of the stub router.
  • Before configuring PIM stub routing, you must also configure either Enhanced Interior Gateway Routing Protocol (EIGRP) stub routing or Open Shortest Path First (OSPF) stub routing on the switch. The PIM stub router does not route the transit traffic between the distribution routers. Unicast (EIGRP) stub routing enforces this behavior. You must configure unicast stub routing to assist the PIM stub router behavior.

    Note


    For information about EIGRP or OSPF configurations, see the Catalyst 3850 Routing Configuration Guide, Release 3SE.


Restrictions for Configuring PIM

The following are the restrictions for configuring PIM:

  • PIM
    • PIM is not supported when running the LAN Base feature set.
    • Bidirectional PIM is not supported.
  • PIM stub routing
    • The IP Services image contains complete multicast routing.
    • In a network using PIM stub routing, the only allowable route for IP traffic to the user is through a switch that is configured with PIM stub routing.
    • The redundant PIM stub router topology is not supported. Only the nonredundant access router topology is supported by the PIM stub feature.
    • Only directly connected multicast (IGMP) receivers and sources are allowed in the Layer 2 access domains. The PIM protocol is not supported in access domains.

Restrictions for Configuring Auto-RP

The following are restrictions for configuring Auto-RP (if used in your network configuration):

  • Auto-RP is not supported when running the LAN Base feature set.
  • If you configure PIM in sparse mode or sparse-dense mode and do not configure Auto-RP, you must manually configure an RP.
  • If routed interfaces are configured in sparse mode, Auto-RP can still be used if all devices are configured with a manual RP address for the Auto-RP groups.
  • If routed interfaces are configured in sparse mode and you enter the ip pim autorp listener global configuration command, Auto-RP can still be used even if all devices are not configured with a manual RP address for the Auto-RP groups.

Restrictions for Configuring Auto-RP and BSR

The following are restrictions for configuring Auto-RP and BSR (if used in your network configuration):

  • If your network is all Cisco routers and multilayer switches, you can use either Auto-RP or BSR.
  • If you have non-Cisco routers in your network, you must use BSR.
  • If you have Cisco PIMv1 and PIMv2 routers and multilayer switches and non-Cisco routers, you must use both Auto-RP and BSR. If your network includes routers from other vendors, configure the Auto-RP mapping agent and the BSR on a Cisco PIMv2 device. Ensure that no PIMv1 device is located in the path a between the BSR and a non-Cisco PIMv2 device.

    Note


    There are two approaches to using PIMv2. You can use Version 2 exclusively in your network or migrate to Version 2 by employing a mixed PIM version environment.


  • Because bootstrap messages are sent hop-by-hop, a PIMv1 device prevents these messages from reaching all routers and multilayer switches in your network. Therefore, if your network has a PIMv1 device in it and only Cisco routers and multilayer switches, it is best to use Auto-RP.
  • If you have a network that includes non-Cisco routers, configure the Auto-RP mapping agent and the BSR on a Cisco PIMv2 router or multilayer switch. Ensure that no PIMv1 device is on the path between the BSR and a non-Cisco PIMv2 router.
  • If you have non-Cisco PIMv2 routers that need to interoperate with Cisco PIMv1 routers and multilayer switches, both Auto-RP and a BSR are required. We recommend that a Cisco PIMv2 device be both the Auto-RP mapping agent and the BSR.

Information About PIM

Protocol-Independent Multicast (PIM) is called protocol-independent because regardless of the unicast routing protocols used to populate the unicast routing table, PIM uses this information to perform multicast forwarding instead of maintaining a separate multicast routing table.

PIM can leverage whichever unicast routing protocols are used to populate the unicast routing table, including EIGRP, OSPF, BGP, or static routes. PIM uses this unicast routing information to perform the multicast forwarding function, so it is IP protocol independent. Although PIM is called a multicast routing protocol, it actually uses the unicast routing table to perform the reverse path forwarding (RPF) check function instead of building up a completely independent multicast routing table. PIM does not send and receive multicast routing updates between routers as the other routing protocols do.

PIM is defined in RFC 4601, Protocol-Independent Multicast-Sparse Mode (PIM-SM): Protocol Specification. PIM is defined in these Internet Engineering Task Force (IETF) Internet drafts:

  • Protocol Independent Multicast (PIM): Motivation and Architecture
  • Protocol Independent Multicast (PIM), Dense Mode Protocol Specification
  • Protocol Independent Multicast (PIM), Sparse Mode Protocol Specification
  • draft-ietf-idmr-igmp-v2-06.txt, Internet Group Management Protocol, Version 2
  • draft-ietf-pim-v2-dm-03.txt, PIM Version 2 Dense Mode

PIM Versions

PIMv2 includes these improvements over PIMv1:

  • A single, active rendezvous point (RP) exists per multicast group, with multiple backup RPs. This single RP compares to multiple active RPs for the same group in PIMv1.
  • A bootstrap router (BSR) provides a fault-tolerant, automated RP discovery and distribution function that enables routers and multilayer switches to dynamically learn the group-to-RP mappings.
  • Sparse mode and dense mode are properties of a group, as opposed to an interface.

    Note


    We strongly recommend using sparse-dense mode as opposed to either sparse mode or dense mode only.


  • PIM join and prune messages have more flexible encoding for multiple address families.
  • A more flexible hello packet format replaces the query packet to encode current and future capability options.
  • Register messages sent to an RP specify whether they are sent by a border router or a designated router.
  • PIM packets are no longer inside IGMP packets; they are standalone packets.

PIMv1 and PIMv2 Interoperability

To avoid misconfiguring multicast routing on your switch, review the information in this section.

The Cisco PIMv2 implementation provides interoperability and transition between Version 1 and Version 2, although there might be some minor problems.

You can upgrade to PIMv2 incrementally. PIM Versions 1 and 2 can be configured on different routers and multilayer switches within one network. Internally, all routers and multilayer switches on a shared media network must run the same PIM version. Therefore, if a PIMv2 device detects a PIMv1 device, the Version 2 device downgrades itself to Version 1 until all Version 1 devices have been shut down or upgraded.

PIMv2 uses the BSR to discover and announce RP-set information for each group prefix to all the routers and multilayer switches in a PIM domain. PIMv1, together with the Auto-RP feature, can perform the same tasks as the PIMv2 BSR. However, Auto-RP is a standalone protocol, separate from PIMv1, and is a proprietary Cisco protocol. PIMv2 is a standards track protocol in the IETF.


Note


We recommend that you use PIMv2. The BSR function interoperates with Auto-RP on Cisco routers and multilayer switches.


When PIMv2 devices interoperate with PIMv1 devices, Auto-RP should have already been deployed. A PIMv2 BSR that is also an Auto-RP mapping agent automatically advertises the RP elected by Auto-RP. That is, Auto-RP sets its single RP on every router or multilayer switch in the group. Not all routers and switches in the domain use the PIMv2 hash function to select multiple RPs.

Dense-mode groups in a mixed PIMv1 and PIMv2 region need no special configuration; they automatically interoperate.

Sparse-mode groups in a mixed PIMv1 and PIMv2 region are possible because the Auto-RP feature in PIMv1 interoperates with the PIMv2 RP feature. Although all PIMv2 devices can also use PIMv1, we recommend that the RPs be upgraded to PIMv2. To ease the transition to PIMv2, we recommend:

  • Using Auto-RP throughout the region.
  • Configuring sparse-dense mode throughout the region.

If Auto-RP is not already configured in the PIMv1 regions, configure Auto-RP.

PIM Modes

PIM can operate in dense mode (DM), sparse mode (SM), or in sparse-dense mode (PIM DM-SM), which handles both sparse groups and dense groups at the same time.

PIM DM

PIM DM builds source-based multicast distribution trees. In dense mode, a PIM DM router or multilayer switch assumes that all other routers or multilayer switches forward multicast packets for a group. If a PIM DM device receives a multicast packet and has no directly connected members or PIM neighbors present, a prune message is sent back to the source to stop unwanted multicast traffic. Subsequent multicast packets are not flooded to this router or switch on this pruned branch because branches without receivers are pruned from the distribution tree, leaving only branches that contain receivers.

When a new receiver on a previously pruned branch of the tree joins a multicast group, the PIM DM device detects the new receiver and immediately sends a graft message up the distribution tree toward the source. When the upstream PIM DM device receives the graft message, it immediately puts the interface on which the graft was received into the forwarding state so that the multicast traffic begins flowing to the receiver.

PIM-SM

PIM-SM uses shared trees and shortest-path-trees (SPTs) to distribute multicast traffic to multicast receivers in the network. In PIM-SM, a router or multilayer switch assumes that other routers or switches do not forward multicast packets for a group, unless there is an explicit request for the traffic (join message). When a host joins a multicast group using IGMP, its directly connected PIM-SM device sends PIM join messages toward the root, also known as the rendezvous point (RP). This join message travels router-by-router toward the root, constructing a branch of the shared tree as it goes.

The RP keeps track of multicast receivers. It also registers sources through register messages received from the source’s first-hop router (designated router [DR]) to complete the shared tree path from the source to the receiver. When using a shared tree, sources must send their traffic to the RP so that the traffic reaches all receivers.

Prune messages are sent up the distribution tree to prune multicast group traffic. This action permits branches of the shared tree or SPT that were created with explicit join messages to be torn down when they are no longer needed.

When the number of PIM-enabled interfaces exceeds the hardware capacity and PIM-SM is enabled with the SPT threshold is set to infinity, the switch does not create (source, group (S, G) ) entries in the multicast routing table for the some directly connected interfaces if they are not already in the table. The switch might not correctly forward traffic from these interfaces.

Multicast Source Discovery Protocol (MSDP)

Multicast Source Discovery Protocol (MSDP) is used for inter-domain source discovery when PIM SM is used. Each PIM administrative domain has its own RP. In order for the RP in one domain to signal new sources to the RP in the other domain, MSDP is used.

When RP in a domain receives a PIM register message for a new source, with MSDP configured it sends a new source-active (SA) message to all its MSDP peers in other domains. Each intermediate MSDP peer floods this SA message away from the originating RP. The MSDP peers install this SA message in their MSDP sa-cache. If the RPs in other domains have any join requests for the group in the SA message (indicated by the presence of a (*,G) entry with non empty outgoing interface list), the domain is interested in the group, and the RP triggers an (S,G) join toward the source.

PIM Stub Routing

The PIM stub routing feature, available in all of the switch software images, reduces resource usage by moving routed traffic closer to the end user.

The PIM stub routing feature supports multicast routing between the distribution layer and the access layer. It supports two types of PIM interfaces: uplink PIM interfaces and PIM passive interfaces. A routed interface configured with the PIM passive mode does not pass or forward PIM control traffic, it only passes and forwards IGMP traffic.

In a network using PIM stub routing, the only allowable route for IP traffic to the user is through a switch that is configured with PIM stub routing. PIM passive interfaces are connected to Layer 2 access domains, such as VLANs, or to interfaces that are connected to other Layer 2 devices. Only directly connected multicast (IGMP) receivers and sources are allowed in the Layer 2 access domains. The PIM passive interfaces do not send or process any received PIM control packets.

When using PIM stub routing, you should configure the distribution and remote routers to use IP multicast routing and configure only the switch as a PIM stub router. The switch does not route transit traffic between distribution routers. You also need to configure a routed uplink port on the switch. The switch uplink port cannot be used with SVIs. If you need PIM for an SVI uplink port, you should upgrade to the IP Services feature set.

You must also configure EIGRP stub routing when configuring PIM stub routing on the switch. For information about this procedure, refer to the Catalyst 3850 IP Routing Configuration Guide.

The redundant PIM stub router topology is not supported. The redundant topology exists when there is more than one PIM router forwarding multicast traffic to a single access domain. PIM messages are blocked, and the PIM asset and designated router election mechanisms are not supported on the PIM passive interfaces. Only the nonredundant access router topology is supported by the PIM stub feature. By using a nonredundant topology, the PIM passive interface assumes that it is the only interface and designated router on that access domain.

Figure 1. PIM Stub Router Configuration. In the following figure, Switch A routed uplink port 25 is connected to the router and PIM stub routing is enabled on the VLAN 100 interfaces and on Host 3. This configuration allows the directly connected hosts to receive traffic from multicast source 200.1.1.3.

IGMP Helper

PIM stub routing moves routed traffic closer to the end user and reduces network traffic. You can also reduce traffic by configuring a stub router (switch) with the IGMP helper feature.

You can configure a stub router (switch) with the ip igmp helper help-address interface configuration command to enable the switch to send reports to the next-hop interface. Hosts that are not directly connected to a downstream router can then join a multicast group sourced from an upstream network. The IGMP packets from a host wanting to join a multicast stream are forwarded upstream to the next-hop device when this feature is configured. When the upstream central router receives the helper IGMP reports or leaves, it adds or removes the interfaces from its outgoing interface list for that group.

For complete syntax and usage information for the ip igmp helper-address command, see the IP Multicast Command Reference, Cisco IOS XE Release 3SE (Catalyst 3850 Switches).

Auto-RP

The PIM-SM protocols require the presence of a rendezvous point (RP) in the network. An RP acts as the meeting place for sources and receivers of multicast data. If a static RP configuration is used, then the configuration needs to be applied on all the routers in the multicast network. To automate this process, the Auto-RP protocol was devised.

This Cisco proprietary feature eliminates the need to manually configure the RP information in every router and multilayer switch in the network. For Auto-RP to work, you configure a Cisco router or multilayer switch as the mapping agent. It uses IP multicast to learn which routers or switches in the network are possible candidate RPs to receive candidate RP announcements. Candidate RPs periodically send multicast RP-announce messages to a particular group or group range to announce their availability.

Mapping agents listen to these candidate RP announcements and use the information to create entries in their group-to-RP mapping caches. Only one mapping cache entry is created for any group-to-RP range received, even if multiple candidate RPs are sending RP announcements for the same range. As the RP-announce messages arrive, the mapping agent selects the router or switch with the highest IP address as the active RP and stores this RP address in the group-to-RP mapping cache.

Mapping agents periodically multicast the contents of their group-to-RP mapping caches. Thus, all routers and switches automatically discover which RP to use for the groups that they support. If a router or switch fails to receive RP-discovery messages and the group-to-RP mapping information expires, it changes to a statically configured RP that was defined with the ip pim rp-address global configuration command. If no statically configured RP exists, the router or switch changes the group to dense-mode operation.

Multiple RPs serve different group ranges or serve as hot backups of each other.

Related References

Auto-RP Benefits

Auto-RP uses IP multicast to automate the distribution of group-to-RP mappings to all Cisco routers and multilayer switches in a PIM network. Auto-RP has these benefits:

  • Easy to use multiple RPs within a network to serve different group ranges.
  • Provides load splitting among different RPs and arrangement of RPs according to the location of group participants.
  • Avoids inconsistent, manual RP configurations on every router and multilayer switch in a PIM network, which can cause connectivity problems.

PIM v2 BSR

PIMv2 BSR (Bootstrap Router) is another method to distribute group-to-RP mapping information to all PIM routers and multilayer switches in the network. It eliminates the need to manually configure RP information in every router and switch in the network. However, instead of using IP multicast to distribute group-to-RP mapping information, BSR uses hop-by-hop flooding of special BSR messages to distribute the mapping information.

The BSR is elected from a set of candidate routers and switches in the domain that have been configured to function as BSRs. The election mechanism is similar to the root-bridge election mechanism used in bridged LANs. The BSR election is based on the BSR priority of the device contained in the BSR messages that are sent hop-by-hop through the network. Each BSR device examines the message and forwards out all interfaces only the message that has either a higher BSR priority than its BSR priority or the same BSR priority, but with a higher BSR IP address. Using this method, the BSR is elected.

The elected BSR sends BSR messages with a TTL of 1. Neighboring PIMv2 routers or multilayer switches receive the BSR message and multicast it out all other interfaces (except the one on which it was received) with a TTL of 1. In this way, BSR messages travel hop-by-hop throughout the PIM domain. Because BSR messages contain the IP address of the current BSR, the flooding mechanism enables candidate RPs to automatically learn which device is the elected BSR.

Candidate RPs send candidate RP advertisements showing the group range for which they are responsible to the BSR, which stores this information in its local candidate-RP cache. The BSR periodically advertises the contents of this cache in BSR messages to all other PIM devices in the domain. These messages travel hop-by-hop through the network to all routers and switches, which store the RP information in the BSR message in their local RP cache. The routers and switches select the same RP for a given group because they all use a common RP hashing algorithm.

Multicast Forwarding and Reverse Path Check

With unicast routing, routers and multilayer switches forward traffic through the network along a single path from the source to the destination host whose IP address appears in the destination address field of the IP packet. Each router and switch along the way makes a unicast forwarding decision, using the destination IP address in the packet, by looking up the destination address in the unicast routing table and forwarding the packet through the specified interface to the next hop toward the destination.

With multicasting, the source is sending traffic to an arbitrary group of hosts represented by a multicast group address in the destination address field of the IP packet. To decide whether to forward or drop an incoming multicast packet, the router or multilayer switch uses a reverse path forwarding (RPF) check on the packet as follows:

  1. The router or multilayer switch examines the source address of the arriving multicast packet to decide whether the packet arrived on an interface that is on the reverse path back to the source.
  2. If the packet arrives on the interface leading back to the source, the RPF check is successful and the packet is forwarded to all interfaces in the outgoing interface list (which might not be all interfaces on the router).
  3. If the RPF check fails, the packet is discarded.

Some multicast routing protocols, such as DVMRP, maintain a separate multicast routing table and use it for the RPF check. However, PIM uses the unicast routing table to perform the RPF check.


Note


DVMRP is not supported on the switch.


Figure 2. RPF Check. The following figure shows port 2 receiving a multicast packet from source 151.10.3.21. The following table shows that the port on the reverse path to the source is port 1, not port 2. Because the RPF check fails, the multilayer switch discards the packet. Another multicast packet from source 151.10.3.21 is received on port 1, and the routing table shows this port is on the reverse path to the source. Because the RPF check passes, the switch forwards the packet to all port in the outgoing port list

Table 1 Routing Table Example for an RPF Check

Network

Port

151.10.0.0/16

Gigabit Ethernet 1/0/1

198.14.32.0/32

Gigabit Ethernet 1/0/3

204.1.16.0/24

Gigabit Ethernet 1/0/4

PIM uses both source trees and RP-rooted shared trees to forward datagrams. The RPF check is performed differently for each:

  • If a PIM router or multilayer switch has a source-tree state (that is, an (S, G) entry is present in the multicast routing table), it performs the RPF check against the IP address of the source of the multicast packet.
  • If a PIM router or multilayer switch has a shared-tree state (and no explicit source-tree state), it performs the RPF check on the RP address (which is known when members join the group).

Sparse-mode PIM uses the RPF lookup function to decide where it needs to send joins and prunes:

  • (S, G) joins (which are source-tree states) are sent toward the source.
  • (*,G) joins (which are shared-tree states) are sent toward the RP.

DVMRP and dense-mode PIM use only source trees and use RPF.


Note


DVMRP is not supported on the switch.


PIM Shared Tree and Source Tree

By default, members of a group receive data from senders to the group across a single data-distribution tree rooted at the RP.

Figure 3. Shared Tree and Source Tree (Shortest-Path Tree). The following figure shows this type of shared-distribution tree. Data from senders is delivered to the RP for distribution to group members joined to the shared tree.

If the data rate warrants, leaf routers (routers without any downstream connections) on the shared tree can use the data distribution tree rooted at the source. This type of distribution tree is called a shortest-path tree or source tree. By default, the software switches to a source tree upon receiving the first data packet from a source.

This process describes the move from a shared tree to a source tree:

  1. A receiver joins a group; leaf Router C sends a join message toward the RP.
  2. The RP puts a link to Router C in its outgoing interface list.
  3. A source sends data; Router A encapsulates the data in a register message and sends it to the RP.
  4. The RP forwards the data down the shared tree to Router C and sends a join message toward the source. At this point, data might arrive twice at Router C, once encapsulated and once natively.
  5. When data arrives natively (unencapsulated) at the RP, it sends a register-stop message to Router A.
  6. By default, reception of the first data packet prompts Router C to send a join message toward the source.
  7. When Router C receives data on (S, G), it sends a prune message for the source up the shared tree.
  8. The RP deletes the link to Router C from the outgoing interface of (S, G). The RP triggers a prune message toward the source.

Join and prune messages are sent for sources and RPs. They are sent hop-by-hop and are processed by each PIM device along the path to the source or RP. Register and register-stop messages are not sent hop-by-hop. They are sent by the designated router that is directly connected to a source and are received by the RP for the group.

Multiple sources sending to groups use the shared tree.

You can configure the PIM device to stay on the shared tree. You can configure the PIM device to stay on the shared tree. For more information, see Delaying the Use of PIM Shortest-Path Tree (CLI).

Default PIM Routing Configuration

This table displays the default PIM routing configuration for the switch.

Table 2 Default Multicast Routing Configuration

Feature

Default Setting

Multicast routing

Disabled on all interfaces.

PIM version

Version 2.

PIM mode

No mode is defined.

PIM stub routing

None configured.

PIM RP address

None configured.

PIM domain border

Disabled.

PIM multicast boundary

None.

Candidate BSRs

Disabled.

Candidate RPs

Disabled.

Shortest-path tree threshold rate

0 kb/s.

PIM router query message interval

30 seconds.

How to Configure PIM

Enabling PIM Stub Routing (CLI)

This procedure is optional.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    interface interface-id

    4.    ip pim passive

    5.    end

    6.    show ip pim interface

    7.    show ip igmp groups detail

    8.    show ip mroute

    9.    show running-config

    10.    copy running-config startup-config


DETAILED STEPS
      Command or Action Purpose
    Step 1 enable


    Example:
    Switch> enable
    
    
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     
    Step 2 configure terminal


    Example:
    
                 
               
    Switch# configure terminal
    
    
     

    Enters the global configuration mode.

     
    Step 3 interface interface-id


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

    Specifies the interface on which you want to enable PIM stub 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 4 ip pim passive


    Example:
    
                 
               
    Switch(config-if)# ip pim passive
    
    
     

    Configures the PIM stub feature on the interface.

     
    Step 5 end


    Example:
    
                 
               
    Switch(config-if)# end
    
    
     

    Returns to privileged EXEC mode.

     
    Step 6 show ip pim interface


    Example:
    
                 
               
    Switch# show ip pim interface
    
    
     

    (Optional) Displays the PIM stub that is enabled on each interface.

     
    Step 7 show ip igmp groups detail


    Example:
    
                 
               
    Switch# show ip igmp groups detail
    
    
     

    (Optional) Displays the interested clients that have joined the specific multicast source group.

     
    Step 8 show ip mroute


    Example:
    
                 
               
    Switch# show ip mroute
    
    
     

    (Optional) Displays the IP multicast routing table.

     
    Step 9 show running-config


    Example:
    
                 
               
    Switch# show running-config
    
    
     

    (Optional) Verifies your entries.

     
    Step 10 copy running-config startup-config


    Example:
    
                 
               
    Switch# copy running-config startup-config
    
    
     

    (Optional) Saves your entries in the configuration file.

     
    Related Concepts

    Configuring a Rendezvous Point

    You must have a rendezvous point (RP), if the interface is in sparse-dense mode and if you want to handle the group as a sparse group. You can use several methods, as described in these sections:


    Note


    You can use Auto-RP, BSR, or a combination of both, depending on the PIM version that you are running and the types of routers in your network. For information about working with different PIM versions in your network, see PIMv1 and PIMv2 Interoperability.


    Manually Assigning an RP to Multicast Groups (CLI)

    If the rendezvous point (RP) for a group is learned through a dynamic mechanism (such as Auto-RP or BSR), you need not perform this task for that RP.

    Senders of multicast traffic announce their existence through register messages received from the source first-hop router (designated router) and forwarded to the RP. Receivers of multicast packets use RPs to join a multicast group by using explicit join messages.


    Note


    RPs are not members of the multicast group; they serve as a meeting place for multicast sources and group members.

    You can configure a single RP for multiple groups defined by an access list. If there is no RP configured for a group, the multilayer switch responds to the group as dense and uses the dense-mode PIM techniques.

    This procedure is optional.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    ip pim rp-address ip-address [ access-list-number] [ override]

      4.    access-list access-list-number { deny | permit} source [ source-wildcard]

      5.    end

      6.    show running-config

      7.    copy running-config startup-config


    DETAILED STEPS
        Command or Action Purpose
      Step 1 enable


      Example:
      Switch> enable
      
      
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.

       
      Step 2 configure terminal


      Example:
      
                    
                  
      Switch# configure terminal
      
      
       

      Enters the global configuration mode.

       
      Step 3 ip pim rp-address ip-address [ access-list-number] [ override]


      Example:
      
                    
                  
      Switch(config)# ip pim rp-address 10.1.1.1 20 override 
      
      
       

      Configures the address of a PIM RP.

      By default, no PIM RP address is configured. You must configure the IP address of RPs on all routers and multilayer switches (including the RP).

      Note    If there is no RP configured for a group, the switch treats the group as dense, using the dense-mode PIM techniques.

      A PIM device can be an RP for more than one group. Only one RP address can be used at a time within a PIM domain. The access list conditions specify for which groups the device is an RP.

      • For ip-address, enter the unicast address of the RP in dotted-decimal notation.
      • (Optional) For access-list-number, enter an IP standard access list number from 1 to 99. If no access list is configured, the RP is used for all groups.
      • (Optional) The override keyword indicates that if there is a conflict between the RP configured with this command and one learned by Auto-RP or BSR, the RP configured with this command prevails.
       
      Step 4 access-list access-list-number { deny | permit} source [ source-wildcard]


      Example:
      
                    
                  
      Switch(config)# access-list 25 permit 10.5.0.1 255.224.0.0 
      
      
       

      Creates a standard access list, repeating the command as many times as necessary.

      • For access-list-number, enter the access list number specified in Step 2.
      • The deny keyword denies access if the conditions are matched.
      • The permit keyword permits access if the conditions are matched.
      • For source, enter the multicast group address for which the RP should be used.
      • (Optional) For source-wildcard, enter the wildcard bits in dotted decimal notation to be applied to the source. Place ones in the bit positions that you want to ignore.

      The access list is always terminated by an implicit deny statement for everything.

       
      Step 5 end


      Example:
      
                    
                  
      Switch(config)# end
      
      
       

      Returns to privileged EXEC mode.

       
      Step 6 show running-config


      Example:
      
                    
                  
      Switch# show running-config 
      
      
       

      Verifies your entries.

       
      Step 7 copy running-config startup-config


      Example:
      
                    
                  
      Switch# copy running-config startup-config
      
      
       

      (Optional) Saves your entries in the configuration file.

       

      Setting Up Auto-RP in a New Internetwork (CLI)

      If you are setting up Auto-RP in a new internetwork, you do not need a default RP because you configure all the interfaces for sparse-dense mode.


      Note


      Omit Step 3 in the following procedure, if you want to configure a PIM router as the RP for the local group.


      SUMMARY STEPS

        1.    enable

        2.    show running-config

        3.    configure terminal

        4.    ip pim send-rp-announce interface-id scope ttl group-list access-list-number interval seconds

        5.    access-list access-list-number { deny | permit} source [ source-wildcard]

        6.    ip pim send-rp-discovery scope ttl

        7.    end

        8.    show running-config

        9.    show ip pim rp mapping

        10.    show ip pim rp

        11.    copy running-config startup-config


      DETAILED STEPS
          Command or Action Purpose
        Step 1 enable


        Example:
        Switch> enable
        
        
         

        Enables privileged EXEC mode.

        • Enter your password if prompted.

         
        Step 2 show running-config


        Example:
        
                      
                    
        Switch# show running-config
        
        
         

        Verifies that a default RP is already configured on all PIM devices and the RP in the sparse-mode network. It was previously configured with the ip pim rp-address global configuration command.

        Note   

        This step is not required for spare-dense-mode environments.

        The selected RP should have good connectivity and be available across the network. Use this RP for the global groups (for example, 224.x.x.x and other global groups). Do not reconfigure the group address range that this RP serves. RPs dynamically discovered through Auto-RP take precedence over statically configured RPs. Assume that it is desirable to use a second RP for the local groups.

         
        Step 3 configure terminal


        Example:
        
                      
                    
        Switch# configure terminal
        
        
         

        Enters the global configuration mode.

         
        Step 4 ip pim send-rp-announce interface-id scope ttl group-list access-list-number interval seconds


        Example:
        Switch(config)# ip pim send-rp-announce gigabitethernet 1/0/5 scope 20 group-list 10 interval 120
        
        
         

        Configures another PIM device to be the candidate RP for local groups.

        • For interface-id, enter the interface type and number that identifies the RP address. Valid interfaces include physical ports, port channels, and VLANs.
        • For scope ttl, specify the time-to-live value in hops. Enter a hop count that is high enough so that the RP-announce messages reach all mapping agents in the network. There is no default setting. The range is 1 to 255.
        • For group-list access-list-number, enter an IP standard access list number from 1 to 99. If no access list is configured, the RP is used for all groups.
        • For interval seconds, specify how often the announcement messages must be sent. The default is 60 seconds. The range is 1 to 16383.

         
        Step 5 access-list access-list-number { deny | permit} source [ source-wildcard]


        Example:
        Switch(config)# access-list 10 permit 10.10.0.0
        
        
         

        Creates a standard access list, repeating the command as many times as necessary.

        • For access-list-number, enter the access list number specified in Step 3.
        • The deny keyword denies access if the conditions are matched.
        • The permit keyword permits access if the conditions are matched.
        • For source, enter the multicast group address range for which the RP should be used.
        • (Optional) For source-wildcard, enter the wildcard bits in dotted decimal notation to be applied to the source. Place ones in the bit positions that you want to ignore.
        Note   

        Recall that the access list is always terminated by an implicit deny statement for everything.

         
        Step 6 ip pim send-rp-discovery scope ttl


        Example:
        Switch(config)# ip pim send-rp-discovery scope 50
        
        
         

        Finds a switch whose connectivity is not likely to be interrupted, and assign it the role of RP-mapping agent.

        For scope ttl, specify the time-to-live value in hops to limit the RP discovery packets. All devices within the hop count from the source device receive the Auto-RP discovery messages. These messages tell other devices which group-to-RP mapping to use to avoid conflicts (such as overlapping group-to-RP ranges). There is no default setting. The range is 1 to 255.

         
        Step 7 end


        Example:
        
                      
                    
        Switch(config)# end
        
        
         

        Returns to privileged EXEC mode.

         
        Step 8 show running-config


        Example:
        Switch# show running-config
        
        
         

        Verifies your entries.

         
        Step 9 show ip pim rp mapping


        Example:
        Switch# show ip pim rp mapping
        
        
         

        Displays active RPs that are cached with associated multicast routing entries.

         
        Step 10 show ip pim rp


        Example:
        Switch# show ip pim rp
        
        
         

        Displays the information cached in the routing table.

         
        Step 11 copy running-config startup-config


        Example:
        Switch# copy running-config startup-config
        
        
         

        (Optional) Saves your entries in the configuration file.

         
        Related Concepts
        Related References

        Adding Auto-RP to an Existing Sparse-Mode Cloud (CLI)

        This section contains suggestions for the initial deployment of Auto-RP into an existing sparse-mode cloud to minimize disruption of the existing multicast infrastructure.

        This procedure is optional.

        SUMMARY STEPS

          1.    enable

          2.    show running-config

          3.    configure terminal

          4.    ip pim send-rp-announce interface-id scope ttl group-list access-list-number interval seconds

          5.    access-list access-list-number { deny | permit} source [ source-wildcard]

          6.    ip pim send-rp-discovery scope ttl

          7.    end

          8.    show running-config

          9.    show ip pim rp mapping

          10.    show ip pim rp

          11.    copy running-config startup-config


        DETAILED STEPS
            Command or Action Purpose
          Step 1 enable


          Example:
          Switch> enable
          
          
           

          Enables privileged EXEC mode.

          • Enter your password if prompted.

           
          Step 2 show running-config


          Example:
          
                        
                      
          Switch# show running-config
          
          
           

          Verifies that a default RP is already configured on all PIM devices and the RP in the sparse-mode network. It was previously configured with the ip pim rp-address global configuration command.

          Note   

          This step is not required for spare-dense-mode environments.

          The selected RP should have good connectivity and be available across the network. Use this RP for the global groups (for example, 224.x.x.x and other global groups). Do not reconfigure the group address range that this RP serves. RPs dynamically discovered through Auto-RP take precedence over statically configured RPs. Assume that it is desirable to use a second RP for the local groups.

           
          Step 3 configure terminal


          Example:
          
                        
                      
          Switch# configure terminal
          
          
           

          Enters the global configuration mode.

           
          Step 4 ip pim send-rp-announce interface-id scope ttl group-list access-list-number interval seconds


          Example:
          Switch(config)# ip pim send-rp-announce gigabitethernet 1/0/5 scope 20 group-list 10 interval 120
          
          
           

          Configures another PIM device to be the candidate RP for local groups.

          • For interface-id, enter the interface type and number that identifies the RP address. Valid interfaces include physical ports, port channels, and VLANs.
          • For scope ttl, specify the time-to-live value in hops. Enter a hop count that is high enough so that the RP-announce messages reach all mapping agents in the network. There is no default setting. The range is 1 to 255.
          • For group-list access-list-number, enter an IP standard access list number from 1 to 99. If no access list is configured, the RP is used for all groups.
          • For interval seconds, specify how often the announcement messages must be sent. The default is 60 seconds. The range is 1 to 16383.

           
          Step 5 access-list access-list-number { deny | permit} source [ source-wildcard]


          Example:
          Switch(config)# access-list 10 permit 224.0.0.0 15.255.255.255 
          
          
           

          Creates a standard access list, repeating the command as many times as necessary.

          • For access-list-number, enter the access list number specified in Step 3.
          • The deny keyword denies access if the conditions are matched.
          • The permit keyword permits access if the conditions are matched.
          • For source, enter the multicast group address range for which the RP should be used.
          • (Optional) For source-wildcard, enter the wildcard bits in dotted decimal notation to be applied to the source. Place ones in the bit positions that you want to ignore.

          Recall that the access list is always terminated by an implicit deny statement for everything.

           
          Step 6 ip pim send-rp-discovery scope ttl


          Example:
          Switch(config)# ip pim send-rp-discovery scope 50
          
           

          Finds a switch whose connectivity is not likely to be interrupted, and assigns it the role of RP-mapping agent.

          For scope ttl, specify the time-to-live value in hops to limit the RP discovery packets. All devices within the hop count from the source device receive the Auto-RP discovery messages. These messages tell other devices which group-to-RP mapping to use to avoid conflicts (such as overlapping group-to-RP ranges). There is no default setting. The range is 1 to 255.

          Note   

          To remove the switch as the RP-mapping agent, use the no ip pim send-rp-discovery global configuration command.

           
          Step 7 end


          Example:
          
                        
                      
          Switch(config)# end
          
          
           

          Returns to privileged EXEC mode.

           
          Step 8 show running-config


          Example:
          Switch# show running-config
          
          
           

          Verifies your entries.

           
          Step 9 show ip pim rp mapping


          Example:
          Switch# 
          show ip pim rp mapping
          
          
           

          Displays active RPs that are cached with associated multicast routing entries.

           
          Step 10 show ip pim rp


          Example:
          Switch# show ip pim rp
          
          
           

          Displays the information cached in the routing table.

           
          Step 11 copy running-config startup-config


          Example:
          Switch# copy running-config startup-config
          
          
           

          (Optional) Saves your entries in the configuration file.

           

          Preventing Join Messages to False RPs (CLI)

          Determine whether the ip pim accept-rp command was previously configured throughout the network by using the show running-config privileged EXEC command. If the ip pim accept-rp command is not configured on any device, this problem can be addressed later. In those routers or multilayer switches already configured with the ip pim accept-rp command, you must enter the command again to accept the newly advertised RP.

          To accept all RPs advertised with Auto-RP and reject all other RPs by default, use the ip pim accept-rp auto-rp global configuration command.

          This procedure is optional.

          Filtering Incoming RP Announcement Messages (CLI)

          You can add configuration commands to the mapping agents to prevent a maliciously configured router from masquerading as a candidate RP and causing problems.

          This procedure is optional.

          SUMMARY STEPS

            1.    enable

            2.    configure terminal

            3.    ip pim rp-announce-filter rp-list access-list-number group-list access-list-number

            4.    access-list access-list-number { deny | permit} source [ source-wildcard]

            5.    end

            6.    show running-config

            7.    copy running-config startup-config


          DETAILED STEPS
              Command or Action Purpose
            Step 1 enable


            Example:
            Switch> enable
            
            
             

            Enables privileged EXEC mode.

            • Enter your password if prompted.

             
            Step 2 configure terminal


            Example:
            
                          
                        
            Switch# configure terminal
            
            
             

            Enters the global configuration mode.

             
            Step 3 ip pim rp-announce-filter rp-list access-list-number group-list access-list-number


            Example:
            Switch(config)# ip pim rp-announce-filter rp-list 10 group-list 14
            
            
             

            Filters incoming RP announcement messages.

            Enter this command on each mapping agent in the network. Without this command, all incoming RP-announce messages are accepted by default.

            For rp-list access-list-number, configure an access list of candidate RP addresses that, if permitted, is accepted for the group ranges supplied in the group-list access-list-number variable. If this variable is omitted, the filter applies to all multicast groups.

            If more than one mapping agent is used, the filters must be consistent across all mapping agents to ensure that no conflicts occur in the group-to-RP mapping information.

             
            Step 4 access-list access-list-number { deny | permit} source [ source-wildcard]


            Example:
            Switch(config)# access-list 10 permit 10.8.1.0 255.255.224.0
            
            
             

            Creates a standard access list, repeating the command as many times as necessary.

            • For access-list-number, enter the access list number specified in Step 2.
            • The deny keyword denies access if the conditions are matched.
            • The permit keyword permits access if the conditions are matched.
            • Create an access list that specifies from which routers and multilayer switches the mapping agent accepts candidate RP announcements (rp-list ACL).
            • Create an access list that specifies the range of multicast groups from which to accept or deny (group-list ACL).
            • For source, enter the multicast group address range for which the RP should be used.
            • (Optional) For source-wildcard, enter the wildcard bits in dotted decimal notation to be applied to the source. Place ones in the bit positions that you want to ignore.

            The access list is always terminated by an implicit deny statement for everything.

             
            Step 5 end


            Example:
            
                          
                        
            Switch(config)# end
            
            
             

            Returns to privileged EXEC mode.

             
            Step 6 show running-config


            Example:
            Switch# show running-config
            
            
             

            Verifies your entries.

             
            Step 7 copy running-config startup-config


            Example:
            Switch# copy running-config startup-config
            
            
             

            (Optional) Saves your entries in the configuration file.

             

            Configuring PIMv2 BSR

            The process for configuring PIMv2 BSR may involve the following optional tasks:

            • Defining the PIM domain border
            • Defining the IP multicast boundary
            • Configuring candidate BSRs
            • Configuring candidate RPs

            Defining the PIM Domain Border (CLI)

            As IP multicast becomes more widespread, the chance of one PIMv2 domain bordering another PIMv2 domain increases. Because two domains probably do not share the same set of RPs, BSR, candidate RPs, and candidate BSRs, you need to constrain PIMv2 BSR messages from flowing into or out of the domain. Allowing messages to leak across the domain borders could adversely affect the normal BSR election mechanism and elect a single BSR across all bordering domains and comingle candidate RP advertisements, resulting in the election of RPs in the wrong domain.

            Figure 4. Constraining PIMv2 BSR Messages. This figure displays how you can configure the PIM domain border by using the ip pim bsr-border command.

            This procedure is optional.

            SUMMARY STEPS

              1.    enable

              2.    configure terminal

              3.    interface interface-id

              4.    ip pim bsr-border

              5.    end

              6.    show running-config

              7.    copy running-config startup-config


            DETAILED STEPS
                Command or Action Purpose
              Step 1 enable


              Example:
              Switch> enable
              
              
               

              Enables privileged EXEC mode.

              • Enter your password if prompted.

               
              Step 2 configure terminal


              Example:
              
                            
                          
              Switch# configure terminal
              
              
               

              Enters the global configuration mode.

               
              Step 3 interface interface-id


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

              Specifies the interface to be configured, 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 4 ip pim bsr-border


              Example:
              Switch(config-if)# ip pim bsr-border
              
              
               

              Defines a PIM bootstrap message boundary for the PIM domain.

              Enter this command on each interface that connects to other bordering PIM domains. This command instructs the switch to neither send nor receive PIMv2 BSR messages on this interface.

              Note   

              To remove the PIM border, use the no ip pim bsr-border interface configuration command.

               
              Step 5 end


              Example:
              
                            
                          
              Switch(config)# end
              
              
               

              Returns to privileged EXEC mode.

               
              Step 6 show running-config


              Example:
              Switch# show running-config
              
              
               

              Verifies your entries.

               
              Step 7 copy running-config startup-config


              Example:
              Switch# copy running-config startup-config
              
              
               

              (Optional) Saves your entries in the configuration file.

               

              Defining the IP Multicast Boundary (CLI)

              You define a multicast boundary to prevent Auto-RP messages from entering the PIM domain. You create an access list to deny packets destined for 224.0.1.39 and 224.0.1.40, which carry Auto-RP information.

              This procedure is optional.

              SUMMARY STEPS

                1.    enable

                2.    configure terminal

                3.    access-list access-list-number deny source [ source-wildcard]

                4.    interface interface-id

                5.    ip multicast boundary access-list-number

                6.    end

                7.    show running-config

                8.    copy running-config startup-config


              DETAILED STEPS
                  Command or Action Purpose
                Step 1 enable


                Example:
                Switch> enable
                
                
                 

                Enables privileged EXEC mode.

                • Enter your password if prompted.

                 
                Step 2 configure terminal


                Example:
                
                              
                            
                Switch# configure terminal
                
                
                 

                Enters the global configuration mode.

                 
                Step 3 access-list access-list-number deny source [ source-wildcard]


                Example:
                Switch(config)# 
                access-list 12 deny 224.0.1.39
                access-list 12 deny 224.0.1.40
                
                
                 

                Creates a standard access list, repeating the command as many times as necessary.

                • For access-list-number, the range is 1 to 99.
                • The deny keyword denies access if the conditions are matched.
                • For source, enter multicast addresses 224.0.1.39 and 224.0.1.40, which carry Auto-RP information.
                • (Optional) For source-wildcard, enter the wildcard bits in dotted decimal notation to be applied to the source. Place ones in the bit positions that you want to ignore.

                The access list is always terminated by an implicit deny statement for everything.

                 
                Step 4 interface interface-id


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

                Specifies the interface to be configured, 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 5 ip multicast boundary access-list-number


                Example:
                Switch(config-if)# ip multicast boundary 12
                
                
                 

                Configures the boundary, specifying the access list you created in Step 2.

                 
                Step 6 end


                Example:
                Switch(config-if)# end
                
                
                 

                Returns to privileged EXEC mode.

                 
                Step 7 show running-config


                Example:
                Switch# show running-config
                
                
                 

                Verifies your entries.

                 
                Step 8 copy running-config startup-config


                Example:
                Switch# copy running-config startup-config
                
                
                 

                (Optional) Saves your entries in the configuration file.

                 

                Configuring Candidate BSRs (CLI)

                You can configure one or more candidate BSRs. The devices serving as candidate BSRs should have good connectivity to other devices and be in the backbone portion of the network.

                This procedure is optional.

                SUMMARY STEPS

                  1.    enable

                  2.    configure terminal

                  3.    ip pim bsr-candidate interface-id hash-mask-length [ priority]

                  4.    end

                  5.    show running-config

                  6.    copy running-config startup-config


                DETAILED STEPS
                    Command or Action Purpose
                  Step 1 enable


                  Example:
                  Switch> enable
                  
                  
                   

                  Enables privileged EXEC mode.

                  • Enter your password if prompted.

                   
                  Step 2 configure terminal


                  Example:
                  
                                
                              
                  Switch# configure terminal
                  
                  
                   

                  Enters the global configuration mode.

                   
                  Step 3 ip pim bsr-candidate interface-id hash-mask-length [ priority]


                  Example:
                  Switch(config)# ip pim bsr-candidate gigabitethernet 1/0/3 28 100
                  
                  
                   

                  Configures your switch to be a candidate BSR.

                  • For interface-id, enter the interface on this switch from which the BSR address is derived to make it a candidate. This interface must be enabled with PIM. Valid interfaces include physical ports, port channels, and VLANs.
                  • For hash-mask-length, specify the mask length (32 bits maximum) that is to be ANDed with the group address before the hash function is called. All groups with the same seed hash correspond to the same RP. For example, if this value is 24, only the first 24 bits of the group addresses matter.
                  • (Optional) For priority, enter a number from 0 to 255. The BSR with the larger priority is preferred. If the priority values are the same, the device with the highest IP address is selected as the BSR. The default is 0.

                   
                  Step 4 end


                  Example:
                  Switch(config-if)# end
                  
                  
                   

                  Returns to privileged EXEC mode.

                   
                  Step 5 show running-config


                  Example:
                  Switch# show running-config
                  
                  
                   

                  Verifies your entries.

                   
                  Step 6 copy running-config startup-config


                  Example:
                  Switch# copy running-config startup-config
                  
                  
                   

                  (Optional) Saves your entries in the configuration file.

                   
                  Related Concepts

                  Configuring the Candidate RPs (CLI)

                  You can configure one or more candidate RPs. Similar to BSRs, the RPs should also have good connectivity to other devices and be in the backbone portion of the network. An RP can serve the entire IP multicast address space or a portion of it. Candidate RPs send candidate RP advertisements to the BSR. When deciding which devices should be RPs, consider these options:

                  • In a network of Cisco routers and multilayer switches where only Auto-RP is used, any device can be configured as an RP.
                  • In a network that includes only Cisco PIMv2 routers and multilayer switches and with routers from other vendors, any device can be used as an RP.
                  • In a network of Cisco PIMv1 routers, Cisco PIMv2 routers, and routers from other vendors, configure only Cisco PIMv2 routers and multilayer switches as RPs.

                  This procedure is optional.

                  SUMMARY STEPS

                    1.    enable

                    2.    configure terminal

                    3.    ip pim rp-candidate interface-id [ group-list access-list-number]

                    4.    access-list access-list-number { deny | permit} source [ source-wildcard]

                    5.    end

                    6.    show running-config

                    7.    copy running-config startup-config


                  DETAILED STEPS
                      Command or Action Purpose
                    Step 1 enable


                    Example:
                    Switch> enable
                    
                    
                     

                    Enables privileged EXEC mode.

                    • Enter your password if prompted.

                     
                    Step 2 configure terminal


                    Example:
                    
                                  
                                
                    Switch# configure terminal
                    
                    
                     

                    Enters the global configuration mode.

                     
                    Step 3 ip pim rp-candidate interface-id [ group-list access-list-number]


                    Example:
                    Switch(config)# ip pim rp-candidate gigabitethernet 1/0/5 group-list 10
                    
                    
                     

                    Configures your switch to be a candidate RP.

                    • For interface-id, specify the interface whose associated IP address is advertised as a candidate RP address. Valid interfaces include physical ports, port channels, and VLANs.
                    • (Optional) For group-list access-list-number, enter an IP standard access list number from 1 to 99. If no group-list is specified, the switch is a candidate RP for all groups.

                     
                    Step 4 access-list access-list-number { deny | permit} source [ source-wildcard]


                    Example:
                    Switch(config)# access-list 10 permit 239.0.0.0 0.255.255.255
                    
                    
                     

                    Creates a standard access list, repeating the command as many times as necessary.

                    • For access-list-number, enter the access list number specified in Step 2.
                    • The deny keyword denies access if the conditions are matched. The permit keyword permits access if the conditions are matched.
                    • For source, enter the number of the network or host from which the packet is being sent.
                    • (Optional) For source-wildcard, enter the wildcard bits in dotted decimal notation to be applied to the source. Place ones in the bit positions that you want to ignore.

                    The access list is always terminated by an implicit deny statement for everything.

                     
                    Step 5 end


                    Example:
                    Switch(config-if)# end
                    
                    
                     

                    Returns to privileged EXEC mode.

                     
                    Step 6 show running-config


                    Example:
                    Switch# show running-config
                    
                    
                     

                    Verifies your entries

                     
                    Step 7 copy running-config startup-config


                    Example:
                    Switch# copy running-config startup-config
                    
                    
                     

                    (Optional) Saves your entries in the configuration file

                     

                    Configuring Auto-RP and BSR for the Network (CLI)

                    If there are only Cisco devices in your network (no routers from other vendors), there is no need to configure a BSR. Configure Auto-RP in a network that is running both PIMv1 and PIMv2.

                    If you have non-Cisco PIMv2 routers that need to interoperate with Cisco PIMv1 routers and multilayer switches, both Auto-RP and a BSR are required. We recommend that a Cisco PIMv2 router or multilayer switch be both the Auto-RP mapping agent and the BSR.

                    If you must have one or more BSRs, we have these recommendations:

                    • Configure the candidate BSRs as the RP-mapping agents for Auto-RP. For information about these procedures, see:
                    • For group prefixes advertised through Auto-RP, the PIMv2 BSR mechanism should not advertise a subrange of these group prefixes served by a different set of RPs. In a mixed PIMv1 and PIMv2 domain, backup RPs should serve the same group prefixes. This prevents the PIMv2 DRs from selecting a different RP from those PIMv1 DRs, due to the longest match lookup in the RP-mapping database.
                    Before You Begin

                    Beginning in privileged EXEC mode, follow these steps to verify the consistency of group-to-RP mappings. This procedure is optional.

                    SUMMARY STEPS

                      1.    show ip pim rp [ hostname or IP address | mapping [ hostname or IP address | elected | in-use ] | metric [ hostname or IP address ] ]

                      2.    show ip pim rp-hash group


                    DETAILED STEPS
                        Command or Action Purpose
                      Step 1 show ip pim rp [ hostname or IP address | mapping [ hostname or IP address | elected | in-use ] | metric [ hostname or IP address ] ]


                      Example:
                      Switch# show ip pim rp mapping 
                       

                      On any Cisco device, displays available RP mappings and metrics:

                      • (Optional) For the hostname, specify the IP name of the group about which to display RPs.
                      • (Optional) For the IP address, specify the IP address of the group about which to display RPs.
                      • (Optional) Use the mapping keyword to display all group-to-RP mappings of which the Cisco device is aware (either configured or learned from Auto-RP).
                      • (Optional) Use the metric keyword to display the RP RPF metric.

                       
                      Step 2 show ip pim rp-hash group


                      Example:
                      
                                   
                                 
                      Switch# show ip pim rp-hash 239.1.1.1 
                      
                      
                       

                      On a PIMv2 router or multilayer switch, confirms that the same RP is the one that a PIMv1 system chooses.

                      For group, enter the group address for which to display RP information.

                       

                      Delaying the Use of PIM Shortest-Path Tree (CLI)

                      The change from shared to source tree happens when the first data packet arrives at the last-hop router. This change occurs because the ip pim spt-threshold global configuration command controls that timing.

                      The shortest-path tree requires more memory than the shared tree but reduces delay. You might want to postpone its use. Instead of allowing the leaf router to immediately move to the shortest-path tree, you can specify that the traffic must first reach a threshold.

                      You can configure when a PIM leaf router should join the shortest-path tree for a specified group. If a source sends at a rate greater than or equal to the specified kbps rate, the multilayer switch triggers a PIM join message toward the source to construct a source tree (shortest-path tree). If the traffic rate from the source drops below the threshold value, the leaf router switches back to the shared tree and sends a prune message toward the source.

                      You can specify to which groups the shortest-path tree threshold applies by using a group list (a standard access list). If a value of 0 is specified or if the group list is not used, the threshold applies to all groups.

                      This procedure is optional.

                      SUMMARY STEPS

                        1.    enable

                        2.    configure terminal

                        3.    access-list access-list-number { deny | permit} source [ source-wildcard]

                        4.    ip pim spt-threshold { kbps | infinity} [ group-list access-list-number]

                        5.    end

                        6.    show running-config

                        7.    copy running-config startup-config


                      DETAILED STEPS
                          Command or Action Purpose
                        Step 1 enable


                        Example:
                        Switch> enable
                        
                        
                         

                        Enables privileged EXEC mode.

                        • Enter your password if prompted.

                         
                        Step 2 configure terminal


                        Example:
                        
                                     
                                   
                        Switch# configure terminal
                        
                        
                         

                        Enters global configuration mode.

                         
                        Step 3 access-list access-list-number { deny | permit} source [ source-wildcard]


                        Example:
                        
                                     
                                   
                        Switch(config)# access-list 16 permit 225.0.0.0 0.255.255.255
                        
                        
                         

                        Creates a standard access list.

                        • For access-list-number, the range is 1 to 99.
                        • The deny keyword denies access if the conditions are matched.
                        • The permit keyword permits access if the conditions are matched.
                        • For source, specify the multicast group to which the threshold will apply.
                        • (Optional) For source-wildcard, enter the wildcard bits in dotted decimal notation to be applied to the source. Place ones in the bit positions that you want to ignore.

                        The access list is always terminated by an implicit deny statement for everything.

                         
                        Step 4 ip pim spt-threshold { kbps | infinity} [ group-list access-list-number]


                        Example:
                        
                                     
                                   
                        Switch(config)# ip pim spt-threshold infinity group-list 16
                        
                        
                         

                        Specifies the threshold that must be reached before moving to shortest-path tree (spt).

                        • For kbps, specify the traffic rate in kilobits per second. The default is 0 kbps.
                          Note   

                          Because of switch hardware limitations, 0 kbps is the only valid entry even though the range is 0 to 4294967.

                        • Specify infinity if you want all sources for the specified group to use the shared tree, never switching to the source tree.
                        • (Optional) For group-list access-list-number, specify the access list created in Step 2. If the value is 0 or if the group list is not used, the threshold applies to all groups.
                         
                        Step 5 end


                        Example:
                        
                                     
                                   
                        Switch(config)# end
                        
                        
                         

                        Returns to privileged EXEC mode.

                         
                        Step 6 show running-config


                        Example:
                        
                                     
                                   
                        Switch# show running-config
                        
                        
                         

                        Verifies your entries.

                         
                        Step 7 copy running-config startup-config


                        Example:
                        
                                     
                                   
                        Switch# copy running-config startup-config
                        
                        
                         

                        (Optional) Saves your entries in the configuration file.

                         

                        Modifying the PIM Router-Query Message Interval (CLI)

                        PIM routers and multilayer switches send PIM router-query messages to find which device will be the designated router (DR) for each LAN segment (subnet). The DR is responsible for sending IGMP host-query messages to all hosts on the directly connected LAN.

                        With PIM DM operation, the DR has meaning only if IGMPv1 is in use. IGMPv1 does not have an IGMP querier election process, so the elected DR functions as the IGMP querier. With PIM-SM operation, the DR is the device that is directly connected to the multicast source. It sends PIM register messages to notify the RP that multicast traffic from a source needs to be forwarded down the shared tree. In this case, the DR is the device with the highest IP address.

                        This procedure is optional.

                        SUMMARY STEPS

                          1.    enable

                          2.    configure terminal

                          3.    interface interface-id

                          4.    ip pim query-interval seconds

                          5.    end

                          6.    show ip igmp interface [ interface-id]

                          7.    copy running-config startup-config


                        DETAILED STEPS
                            Command or Action Purpose
                          Step 1 enable


                          Example:
                          Switch> enable
                          
                          
                           

                          Enables privileged EXEC mode.

                          • Enter your password if prompted.

                           
                          Step 2 configure terminal


                          Example:
                          
                                       
                                     
                          Switch# configure terminal
                          
                          
                           

                          Enters the global configuration mode.

                           
                          Step 3 interface interface-id


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

                          Specifies the interface to be configured, 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 4 ip pim query-interval seconds


                          Example:
                          
                                       
                                     
                          Switch(config-if)# ip pim query-interval 45
                          
                          
                           

                          Configures the frequency at which the switch sends PIM router-query messages.

                          The default is 30 seconds. The range is 1 to 65535.

                           
                          Step 5 end


                          Example:
                          
                                       
                                     
                          Switch(config-if)# end
                          
                          
                           

                          Returns to privileged EXEC mode.

                           
                          Step 6 show ip igmp interface [ interface-id]


                          Example:
                          
                                       
                                     
                          Switch# show ip igmp interface
                          
                          
                           

                          Verifies your entries.

                           
                          Step 7 copy running-config startup-config


                          Example:
                          
                                       
                                     
                          Switch# copy running-config startup-config
                          
                          
                           

                          (Optional) Saves your entries in the configuration file.

                           

                          Monitoring PIM

                          Use the privileged EXEC commands in the following table to monitor your PIM configurations.

                          Table 3 PIM Monitoring Commands

                          Command

                          Purpose

                          show ip pim all-vrfs tunnel [tunnel tunnel_number | verbose]

                          Displays all VRFs.

                          show ip pim autorp

                          Displays global auto-RP information.

                          show ip pim boundary

                          Displays information about mroutes filtered by administratively scoped IPv4 multicast boundaries configured on an interface.

                          show ip pim interface

                          Displays information about interfaces configured for Protocol Independent Multicast (PIM).

                          show ip pim neighbor

                          Displays the PIM neighbor information.

                          show ip pim tunnel [tunnel | verbose]

                          Displays information about Protocol Independent Multicast (PIM) tunnel interfaces

                          show ip pim vrf { word { all-vrfs | autorp | boundary | bsr-router | interface | mdt | neighbor | rp | rp-hash | tunnel } }

                          Displays the VPN routing/forwarding instance.

                          Monitoring RP Mapping

                          Use the privileged EXEC commands in the following table to monitor RP mapping.

                          Table 4 RP Mapping Monitoring Commands

                          Command

                          Purpose

                          show ip pim bsr

                          Displays information about the elected BSR.

                          show ip pim bsr-router

                          Displays information about the BSRv2.

                          show ip pim rp [ hostname or IP address | mapping [ hostname or IP address | elected [hostname or IP address] | in-use [hostname or IP address] ] | metric [ hostname or IP address ] ]

                          Displays how the switch learns of the RP (through the BSR or the Auto-RP mechanism).

                          show ip pim rp-hash hostname or IP group address

                          Displays the RP that was selected for the specified group.

                          Troubleshooting PIMv1 and PIMv2 Interoperability Problems

                          When debugging interoperability problems between PIMv1 and PIMv2, check these in the order shown:

                          1. Verify RP mapping with the show ip pim rp-hash privileged EXEC command, making sure that all systems agree on the same RP for the same group.
                          2. Verify interoperability between different versions of DRs and RPs. Make sure that the RPs are interacting with the DRs properly (by responding with register-stops and forwarding decapsulated data packets from registers).

                          Configuration Examples for PIM

                          Example: Enabling PIM Stub Routing

                          In this example, IP multicast routing is enabled, Switch A PIM uplink port 25 is configured as a routed uplink port with spare-dense-mode enabled. PIM stub routing is enabled on the VLAN 100 interfaces and on Gigabit Ethernet port 20.

                          
                                    
                                  
                          Switch(config)# ip multicast-routing distributed
                          Switch(config)# interface GigabitEthernet3/0/25
                          Switch(config-if)# no switchport
                          Switch(config-if)# ip address 3.1.1.2 255.255.255.0
                          Switch(config-if)# ip pim sparse-dense-mode
                          Switch(config-if)# exit
                          Switch(config)# interface vlan100
                          Switch(config-if)# ip pim passive
                          Switch(config-if)# exit
                          Switch(config)# interface GigabitEthernet3/0/20
                          Switch(config-if)# ip pim passive
                          Switch(config-if)# exit
                          Switch(config)# interface vlan100
                          Switch(config-if)# ip address 100.1.1.1 255.255.255.0
                          Switch(config-if)# ip pim passive
                          Switch(config-if)# exit
                          Switch(config)# interface GigabitEthernet3/0/20
                          Switch(config-if)# no switchport
                          Switch(config-if)# ip address 10.1.1.1 255.255.255.0
                          Switch(config-if)# ip pim passive
                          Switch(config-if)# end
                          
                          
                          Related Concepts

                          Example: Verifying PIM Stub Routing

                          To verify that PIM stub is enabled for each interface, use the show ip pim interface privileged EXEC command:

                          
                                    
                                  
                          Switch# show ip pim interface
                          Address Interface Ver/ Nbr Query DR DR
                          Mode Count Intvl Prior
                          3.1.1.2 GigabitEthernet3/0/25 v2/SD 1 30 1 3.1.1.2
                          100.1.1.1 Vlan100 v2/P 0 30 1 100.1.1.1
                          10.1.1.1 GigabitEthernet3/0/20 v2/P 0 30 1 10.1.1.1
                          
                          

                          Example: Manually Assigning an RP to Multicast Groups

                          This example shows how to configure the address of the RP to 147.106.6.22 for multicast group 225.2.2.2 only:

                          
                                    
                                  
                          Switch(config)# access-list 1 permit 225.2.2.2 0.0.0.0
                          Switch(config)# ip pim rp-address 147.106.6.22 1
                          
                          

                          Example: Configuring Auto-RP

                          This example shows how to send RP announcements out all PIM-enabled interfaces for a maximum of 31 hops. The IP address of port 1 is the RP. Access list 5 describes the group for which this switch serves as RP:

                          
                                    
                                  
                          Switch(config)# ip pim send-rp-announce gigabitethernet1/0/1 scope 31 group-list 5
                          Switch(config)# access-list 5 permit 224.0.0.0 15.255.255.255
                          
                          
                          Related Concepts

                          Example: Defining the IP Multicast Boundary to Deny Auto-RP Information

                          This example shows a portion of an IP multicast boundary configuration that denies Auto-RP information:

                          
                                    
                                  
                          Switch(config)# access-list 1 deny 224.0.1.39
                          Switch(config)# access-list 1 deny 224.0.1.40
                          Switch(config)# access-list 1 permit all
                          Switch(config)# interface gigabitethernet1/0/1
                          Switch(config-if)# ip multicast boundary 1
                          
                          

                          Example: Filtering Incoming RP Announcement Messages

                          This example shows a sample configuration on an Auto-RP mapping agent that is used to prevent candidate RP announcements from being accepted from unauthorized candidate RPs:

                          
                                    
                                  
                          Switch(config)# ip pim rp-announce-filter rp-list 10 group-list 20
                          Switch(config)# access-list 10 permit host 172.16.5.1
                          Switch(config)# access-list 10 permit host 172.16.2.1
                          Switch(config)# access-list 20 deny 239.0.0.0 0.0.255.255
                          Switch(config)# access-list 20 permit 224.0.0.0 15.255.255.255
                          
                          

                          The mapping agent accepts candidate RP announcements from only two devices, 172.16.5.1 and 172.16.2.1. The mapping agent accepts candidate RP announcements from these two devices only for multicast groups that fall in the group range of 224.0.0.0 to 239.255.255.255. The mapping agent does not accept candidate RP announcements from any other devices in the network. Furthermore, the mapping agent does not accept candidate RP announcements from 172.16.5.1 or 172.16.2.1 if the announcements are for any groups in the 239.0.0.0 through 239.255.255.255 range. This range is the administratively scoped address range.

                          Example: Preventing Join Messages to False RPs

                          If all interfaces are in sparse mode, use a default-configured RP to support the two well-known groups 224.0.1.39 and 224.0.1.40. Auto-RP uses these two well-known groups to collect and distribute RP-mapping information. When this is the case and the ip pim accept-rp auto-rp command is configured, another ip pim accept-rp command accepting the RP must be configured as follows:

                          
                                    
                                  
                          Switch(config)# ip pim accept-rp 172.10.20.1 1
                          Switch(config)# access-list 1 permit 224.0.1.39
                          Switch(config)# access-list 1 permit 224.0.1.40
                          
                          

                          Example: Configuring Candidate BSRs

                          This example shows how to configure a candidate BSR, which uses the IP address 172.21.24.18 on a port as the advertised BSR address, uses 30 bits as the hash-mask-length, and has a priority of 10.

                          
                                    
                                  
                          Switch(config)# interface gigabitethernet1/0/2
                          Switch(config-if)# ip address 172.21.24.18 255.255.255.0
                          Switch(config-if)# ip pim sparse-dense-mode
                          Switch(config-if)# ip pim bsr-candidate gigabitethernet1/0/2 30 10
                          
                          
                          Related Concepts

                          Example: Configuring Candidate RPs

                          This example shows how to configure the switch to advertise itself as a candidate RP to the BSR in its PIM domain. Standard access list number 4 specifies the group prefix associated with the RP that has the address identified by a port. That RP is responsible for the groups with the prefix 239.

                          
                                    
                                  
                          Switch(config)# ip pim rp-candidate gigabitethernet1/0/2 group-list 4
                          Switch(config)# access-list 4 permit 239.0.0.0 0.255.255.255
                          
                          

                          Where to Go Next for PIM

                          You can configure the following:

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

                          Additional References

                          Related Documents

                          Related Topic Document Title

                          PIM is defined in RFC 4601 and in these Internet Engineering Task Force (IETF) Internet drafts.

                          • Protocol Independent Multicast (PIM): Motivation and Architecture
                          • Protocol Independent Multicast (PIM), Dense Mode Protocol Specification
                          • Protocol Independent Multicast (PIM), Sparse Mode Protocol Specification
                          • draft-ietf-idmr-igmp-v2-06.txt, Internet Group Management Protocol, Version 2
                          • draft-ietf-pim-v2-dm-03.txt, PIM Version 2 Dense Mode

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

                          IP Multicast Routing Command Reference (Catalyst 3850 Switches)

                          IGMP Helper command syntax and usage information.

                          IP Multicast Routing Command Reference (Catalyst 3850 Switches)

                          Multicast Source Discovery Protocol (MSDP)

                          IP Routing: Protocol-Independent Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches)

                          Enhanced Interior Gateway Routing Protocol (EIGRP) stub routing

                          IP Routing: EIGRP Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches)

                          Open Shortest Path First (OSPF) stub routing

                          IP Routing: OSPF Configuration Guide, Cisco IOS XE 3SE (Catalyst 3850 Switches)

                          Platform-independent configuration information

                          • IP Multicast: PIM Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches)
                          • IP Multicast: IGMP Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches)
                          • IP Multicast: Multicast Optimization Configuration Guide, Cisco IOS XE Release 3SE (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 4601

                          Protocol-Independent Multicast-Sparse Mode (PIM-SM): Protocol Specification

                          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 PIM

                          Release

                          Modification

                          Cisco IOS XE 3.2SE

                          This feature was introduced.