Configuring MSDP

Finding Feature Information

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Information About Multicast Source Discovery Protocol

MSDP is a mechanism to connect multiple PIM-SM domains. The purpose of MSDP is to discover multicast sources in other PIM domains. The main advantage of MSDP is that it reduces the complexity of interconnecting multiple PIM-SM domains by allowing PIM-SM domains to use an interdomain source tree (rather than a common shared tree). When MSDP is configured in a network, RPs exchange source information with RPs in other domains. An RP can join the interdomain source tree for sources that are sending to groups for which it has receivers. The RP can do that because it is the root of the shared tree within its domain, which has branches to all points in the domain where there are active receivers. When a last-hop device learns of a new source outside the PIM-SM domain (through the arrival of a multicast packet from the source down the shared tree), it then can send a join toward the source and join the interdomain source tree.


Note

If the RP either has no shared tree for a particular group or a shared tree whose outgoing interface list is null, it does not send a join to the source in another domain.

When MSDP is enabled, an RP in a PIM-SM domain maintains MSDP peering relationships with MSDP-enabled devices in other domains. This peering relationship occurs over a TCP connection, where primarily a list of sources sending to multicast groups is exchanged. MSDP uses TCP (port 639) for its peering connections. As with BGP, using point-to-point TCP peering means that each peer must be explicitly configured. The TCP connections between RPs, moreover, are achieved by the underlying routing system. The receiving RP uses the source lists to establish a source path. If the multicast sources are of interest to a domain that has receivers, multicast data is delivered over the normal, source-tree building mechanism provided by PIM-SM. MSDP is also used to announce sources sending to a group. These announcements must originate at the RP of the domain.

The figure illustrates MSDP operating between two MSDP peers. PIM uses MSDP as the standard mechanism to register a source with the RP of a domain.

Figure 1. MSDP Running Between RP Peers

When MSDP is implemented, the following sequence of events occurs:

  1. When a PIM designated device (DR) registers a source with its RP as illustrated in the figure, the RP sends a Source-Active (SA) message to all of its MSDP peers.

Note

The DR sends the encapsulated data to the RP only once per source (when the source goes active). If the source times out, this process happens again when it goes active again. This situation is different from the periodic SA message that contains all sources that are registered to the originating RP. Those SA messages are MSDP control packets, and, thus, do not contain encapsulated data from active sources.

  1. The SA message identifies the source address, the group that the source is sending to, and the address or the originator ID of the RP, if configured.
  2. Each MSDP peer that receives the SA message floods the SA message to all of its peers downstream from the originator. In some cases (such as the case with the RPs in PIM-SM domains B and C in the figure), an RP may receive a copy of an SA message from more than one MSDP peer. To prevent looping, the RP consults the BGP next-hop database to determine the next hop toward the originator of the SA message. If both MBGP and unicast BGP are configured, MBGP is checked first, and then unicast BGP. That next-hop neighbor is the RPF-peer for the originator. SA messages that are received from the originator on any interface other than the interface to the RPF peer are dropped. The SA message flooding process, therefore, is referred to as peer-RPF flooding. Because of the peer-RPF flooding mechanism, BGP or MBGP must be running in conjunction with MSDP.
  1. When an RP receives an SA message, it checks to see whether there are any members of the advertised groups in its domain by checking to see whether there are interfaces on the group’s (*, G) outgoing interface list. If there are no group members, the RP does nothing. If there are group members, the RP sends an (S, G) join toward the source. As a result, a branch of the interdomain source tree is constructed across autonomous system boundaries to the RP. As multicast packets arrive at the RP, they are then forwarded down its own shared tree to the group members in the RP’s domain. The members’ DRs then have the option of joining the rendezvous point tree (RPT) to the source using standard PIM-SM procedures.
  2. The originating RP continues to send periodic SA messages for the (S, G) state every 60 seconds for as long as the source is sending packets to the group. When an RP receives an SA message, it caches the SA message. Suppose, for example, that an RP receives an SA message for (172.16.5.4, 228.1.2.3) from originating RP 10.5.4.3. The RP consults its mroute table and finds that there are no active members for group 228.1.2.3, so it passes the SA message to its peers downstream of 10.5.4.3. If a host in the domain then sends a join to the RP for group 228.1.2.3, the RP adds the interface toward the host to the outgoing interface list of its (*, 224.1.2.3) entry. Because the RP caches SA messages, the device will have an entry for (172.16.5.4, 228.1.2.3) and can join the source tree as soon as a host requests a join.

Note

In all current and supported software releases, caching of MSDP SA messages is mandatory and cannot be manually enabled or disabled. By default, when an MSDP peer is configured, the ip multicast cache-sa-state command will automatically be added to the running configuration.

MSDP Benefits

MSDP has these benefits:

  • It breaks up the shared multicast distribution tree. You can make the shared tree local to your domain. Your local members join the local tree, and join messages for the shared tree never need to leave your domain.
  • PIM sparse-mode domains can rely only on their own RPs, decreasing reliance on RPs in another domain. This increases security because you can prevent your sources from being known outside your domain.
  • Domains with only receivers can receive data without globally advertising group membership.
  • Global source multicast routing table state is not required, saving memory.

Default MSDP Peers

A stub autonomous system also might want to have MSDP peerings with more than one RP for the sake of redundancy. For example, SA messages cannot just be accepted from multiple default peers, because there is no RPF check mechanism. Instead, SA messages are accepted from only one peer. If that peer fails, SA messages are then accepted from the other peer. The underlying assumption here, of course, is that both default peers are sending the same SA messages.

The figure illustrates a scenario where default MSDP peers might be used. In the figure, a customer that owns Device B is connected to the Internet through two Internet service providers (ISPs), one that owns Device A and the other that owns Device C. They are not running BGP or MBGP between them. In order for the customer to learn about sources in the ISP domain or in other domains, Device B identifies Device A as its default MSDP peer. Device B advertises SA messages to both Device A and Device C, but accepts SA messages either from Device A only or Device C only. If Device A is the first default peer in the configuration, it will be used if it is up and running. Only if Device A is not running will Device B accept SA messages from Device C.

The ISP will also likely use a prefix list to define which prefixes it will accept from the customer device. The customer will define multiple default peers, each having one or more prefixes associated with it.

The customer has two ISPs to use. The customer defines both ISPs as default peers. As long as the first default peer identified in the configuration is up and running, it will be the default peer and the customer will accept all SA messages it receives from that peer.

Figure 2. Default MSDP Peer Scenario

Device B advertises SAs to Device A and Device C, but uses only Device A or Device C to accept SA messages. If Device A is first in the configuration, it will be used if it is up and running. Only when Device A is not running will Device B accept SAs from Device C. This is the behavior without a prefix list.

If you specify a prefix list, the peer will be a default peer only for the prefixes in the list. You can have multiple active default peers when you have a prefix list associated with each. When you do not have any prefix lists, you can configure multiple default peers, but only the first one is the active default peer as long as the device has connectivity to this peer and the peer is alive. If the first configured peer goes down or the connectivity to this peer goes down, the second configured peer becomes the active default, and so on.

MSDP Mesh Groups

An MSDP mesh group is a group of MSDP speakers that have fully meshed MSDP connectivity between one another. In other words, each of the MSDP peers in the group must have an MSDP peering relationship (MSDP connection) to every other MSDP peer in the group. When an MSDP mesh group is configured between a group of MSDP peers, SA message flooding is reduced. Because when an MSDP peer in the group receives an SA message from another MSDP peer in the group, it assumes that this SA message was sent to all the other MSDP peers in the group. As a result, it is not necessary for the receiving MSDP peer to flood the SA message to the other MSDP peers in the group.

Benefits of MSDP Mesh Groups

  • Optimizes SA flooding--MSDP mesh groups are particularly useful for optimizing SA flooding when two or more peers are in a group.
  • Reduces the amount of SA traffic across the Internet--When MSDP mesh groups are used, SA messages are not flooded to other mesh group peers.
  • Eliminates RPF checks on arriving SA messages--When an MSDP mesh group is configured, SA messages are always accepted from mesh group peers.

SA Origination Filters

By default, an RP that is configured to run MSDP will originate SA messages for all local sources for which it is the RP. Local sources that register with an RP, therefore, will be advertised in SA messages, which in some cases is not desirable. For example, if sources inside a PIM-SM domain are using private addresses (for example, network 10.0.0.0/8), you should configure an SA origination filter to restrict those addresses from being advertised to other MSDP peers across the Internet.

To control what sources are advertised in SA messages, you can configure SA origination filters on an RP. By creating SA origination filters, you can control the sources advertised in SA messages as follows:

  • You can configure an RP to prevent the device from advertising local sources in SA messages. The device will still forward SA messages from other MSDP peers in the normal fashion; it will just not originate any SA messages for local sources.
  • You can configure the device to only originate SA messages for local sources sending to specific groups that match (S, G) pairs defined in the extended access list. All other local sources will not be advertised in SA messages.
  • You can configure the device to only originate SA messages for local sources sending to specific groups that the match AS paths defined in an AS-path access list. All other local sources will not be advertised in SA messages.
  • You can configure the device to only originate SA messages for local sources that match the criteria defined in the route map. All other local sources will not be advertised in SA messages.
  • You configure an SA origination filter that includes an extended access list, an AS-path access list, and route map, or a combination thereof. In this case, all conditions must be true before any local sources are advertised in SA messages.

Use of Outgoing Filter Lists in MSDP

By default, an MSDP-enabled device forwards all SA messages it receives to all of its MSDP peers. However, you can prevent SA messages from being forwarded to MSDP peers by creating outgoing filter lists. Outgoing filter lists apply to all SA messages, whether locally originated or received from another MSDP peer, whereas SA origination filters apply only to locally originated SA messages. For more information about enabling a filter for MSDP SA messages originated by the local device, see the Controlling SA Messages Originated by an RP for Local Sources section.

By creating an outgoing filter list, you can control the SA messages that a device forwards to a peer as follows:

  • You can filter all outgoing SA messages forwarded to a specified MSDP peer by configuring the device to stop forwarding its SA messages to the MSDP peer.
  • You can filter a subset of outgoing SA messages forwarded to a specified MSDP peer based on (S, G) pairs defined in an extended access list by configuring the device to only forward SA messages to the MSDP peer that match the (S, G) pairs permitted in an extended access list. The forwarding of all other SA messages to the MSDP peer will be stopped.
  • You can filter a subset of outgoing SA messages forwarded to a specified MSDP peer based on match criteria defined in a route map by configuring the device to only forward SA messages that match the criteria defined in the route map. The forwarding of all other SA messages to the MSDP peer will be stopped.
  • You can filter a subset of outgoing SA messages from a specified peer based on the announcing RP address contained in the SA message by configuring the device to filter outgoing SA messages based on their origin, even after an SA message has been transmitted across one or more MSDP peers. The forwarding of all other SA messages to the MSDP peer will be stopped.
  • You can configure an outgoing filter list that includes an extended access list, a route map, and either an RP access list or an RP route map. In this case, all conditions must be true for the MSDP peer to forward the outgoing SA message.

Caution

Arbitrary filtering of SA messages can result in downstream MSDP peers being starved of SA messages for legitimate active sources. Care, therefore, should be taken when using these sorts of filters. Normally, outgoing filter lists are used only to reject undesirable sources, such as sources using private addresses.

Use of Incoming Filter Lists in MSDP

By default, an MSDP-enabled device receives all SA messages sent to it from its MSDP peers. However, you can control the source information that a device receives from its MSDP peers by creating incoming filter lists.

By creating incoming filter lists, you can control the incoming SA messages that a device receives from its peers as follows:

  • You can filter all incoming SA messages from a specified MSDP peer by configuring the device to ignore all SA messages sent to it from the specified MSDP peer.
  • You can filter a subset of incoming SA messages from a specified peer based on (S, G) pairs defined in an extended access list by configuring the device to only receive SA messages from the MSDP peer that match the (S, G) pairs defined in the extended access list. All other incoming SA messages from the MSDP peer will be ignored.
  • You can filter a subset of incoming SA request messages from a specified peer based on match criteria defined in a route map by configuring the device to only receive SA messages that match the criteria defined in the route map. All other incoming SA messages from the MSDP peer will be ignored.
  • You can filter a subset of incoming SA messages from a specified peer based on both (S, G) pairs defined in an extended access list and on match criteria defined in a route map by configuring the device to only receive incoming SA messages that both match the (S, G) pairs defined in the extended access list and match the criteria defined in the route map. All other incoming SA messages from the MSDP peer will be ignored.
  • You can filter a subset of incoming SA messages from a specified peer based on the announcing RP address contained in the SA message by configuring the device to filter incoming SA messages based on their origin, even after the SA message may have already been transmitted across one or more MSDP peers.
  • You can configure an incoming filter list that includes an extended access list, a route map, and either an RP access list or an RP route map. In this case, all conditions must be true for the MSDP peer to receive the incoming SA message.

Caution

Arbitrary filtering of SA messages can result in downstream MSDP peers being starved of SA messages for legitimate active sources. Care, therefore, should be taken when using these sorts of filters. Normally, incoming filter lists are used only to reject undesirable sources, such as sources using private addresses.

TTL Thresholds in MSDP

The time-to-live (TTL) value provides a means to limit the number of hops a packet can take before being dropped. The ip multicast ttl-threshold command is used to specify a TTL for data-encapsulated SA messages sent to specified MSDP peers. By default, multicast data packets in SA messages are sent to an MSDP peer, provided the TTL value of the packet is greater than 0, which is standard TTL behavior.

In general, a TTL-threshold problem can be introduced by the encapsulation of a source’s initial multicast packet in an SA message. Because the multicast packet is encapsulated inside of the unicast SA message (whose TTL is 255), its TTL is not decremented as the SA message travels to the MSDP peer. Furthermore, the total number of hops that the SA message traverses can be drastically different than a normal multicast packet because multicast and unicast traffic may follow completely different paths to the MSDP peer and hence the remote PIM-SM domain. As a result, encapsulated packets can end up violating TTL thresholds. The solution to this problem is to configure a TTL threshold that is associated with any multicast packet that is encapsulated in an SA message sent to a particular MSDP peer using the ip multicast ttl-threshold command. The ip msdp ttl-threshold command prevents any multicast packet whose TTL in the IP header is less than the TTL value specified for the ttl-valueargument from being encapsulated in SA messages sent to that peer.

MSDP Message Types

There are four basic MSDP message types, each encoded in their own Type, Length, and Value (TLV) data format.

SA Messages

SA messages are used to advertise active sources in a domain. In addition, these SA messages may contain the initial multicast data packet that was sent by the source.

SA messages contain the IP address of the originating RP and one or more (S, G) pairs being advertised. In addition, the SA message may contain an encapsulated data packet.

SA Request Messages

SA request messages are used to request a list of active sources for a specific group. These messages are sent to an MSDP SA cache that maintains a list of active (S, G) pairs in its SA cache. Join latency can be reduced by using SA request messages to request the list of active sources for a group instead of having to wait up to 60 seconds for all active sources in the group to be readvertised by originating RPs.

SA Response Messages

SA response messages are sent by the MSDP peer in response to an SA request message. SA response messages contain the IP address of the originating RP and one or more (S, G) pairs of the active sources in the originating RP’s domain that are stored in the cache.

Keepalive Messages

Keepalive messages are sent every 60 seconds in order to keep the MSDP session active. If no keepalive messages or SA messages are received for 75 seconds, the MSDP session is reset.

Default MSDP Configuration

MSDP is not enabled, and no default MSDP peer exists.

How to Configure MSDP

Configuring a Default MSDP Peer

Before You Begin

Configure an MSDP peer.

     Command or ActionPurpose
    Step 1configure terminal


    Example: 
    Router# configure terminal
     

    Enters global configuration mode.

     
    Step 2ip msdp default-peer ip-address | name [prefix-list list]


    Example: 
    Router(config)# ip msdp default-peer 10.1.1.1 prefix-list site-a
     

    Defines a default peer from which to accept all MSDP SA messages.

    • For ip-address | name, enter the IP address or Domain Name System (DNS) server name of the MSDP default peer.
    • (Optional) For prefix-list list, enter the list name that specifies the peer to be the default peer only for the listed prefixes. You can have multiple active default peers when you have a prefix list associated with each. When you enter multiple ip msdp default-peer commands with the prefix-list keyword, you use all the default peers at the same time for different RP prefixes. This syntax is typically used in a service provider cloud that connects stub site clouds. When you enter multiple ip msdp default-peer commands without the prefix-list keyword, a single active peer accepts all SA messages. If that peer fails, the next configured default peer accepts all SA messages. This syntax is typically used at a stub site.
     
    Step 3ip prefix-list name [description string] | seq number {permit | deny} network length


    Example: 
    Router(config)# prefix-list site-a seq 3 permit 12 network length 128
     

    (Optional) Creates a prefix list using the name specified in Step 2.

    • (Optional) For description string, enter a description of up to 80 characters to describe this prefix list.
    • For seq number, enter the sequence number of the entry. The range is 1 to 4294967294.
    • The deny keyword denies access to matching conditions.
    • The permit keyword permits access to matching conditions.
    • For network length, specify the network number and length (in bits) of the network mask that is permitted or denied.
     
    Step 4ip msdp description {peer-name | peer-address} text


    Example: 
    Router(config)# ip msdp description peer-name site-b
     

    (Optional) Configures a description for the specified peer to make it easier to identify in a configuration or in show command output.

    By default, no description is associated with an MSDP peer.

     
    Step 5end


    Example: 
    Router(config)# end
     

    Returns to privileged EXEC mode.

     
    Step 6show running-config


    Example: 
    Router# show running-config
     

    Verifies your entries.

     
    Step 7copy running-config startup-config


    Example: 
    Router# copy running-config startup-config
     

    (Optional) Saves your entries in the configuration file.

     

    Caching Source-Active State

    If you want to sacrifice some memory in exchange for reducing the latency of the source information, you can configure the switch to cache SA messages. Perform the following steps to enable the caching of source/group pairs:

    This procedure is optional.

       Command or ActionPurpose
      Step 1
              		 
      Step 2configure terminal


      Example: 
      Switch# configure terminal
       

      Enters global configuration mode.

       
      Step 3ip msdp cache-sa-state [list access-list-number]


      Example: 
      Switch(config)# ip msdp cache-sa-state 100
       

      Enables the caching of source/group pairs (create an SA state). Those pairs that pass the access list are cached.

      For list access-list-number, the range is 100 to 199.

      Note   

      An alternative to this command is the ip msdp sa-reques global configuration command, which causes the switch to send an SA request message to the MSDP peer when a new member for a group becomes active.

       
      Step 4access-list access-list-number {deny | permit} protocol source source-wildcard destination destination-wildcard


      Example: 
      Switch(config)# access-list 100 permit ip 171.69.0.0 0.0.255.255 224.2.0.0 0.0.255.255
       

      Creates an IP extended access list, repeating the command as many times as necessary.

      • For access-list-number, the range is 100 to 199. Enter the same number created in Step 2.
      • The deny keyword denies access if the conditions are matched. The permit keyword permits access if the conditions are matched.
      • For protocol, enter ip as the protocol name.
      • For source, enter the number of the network or host from which the packet is being sent.
      • 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.
      • For destination, enter the number of the network or host to which the packet is being sent.
      • For destination-wildcard, enter the wildcard bits in dotted decimal notation to be applied to the destination. 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 5end


      Example: 
      Switch(config)# end
       

      Returns to privileged EXEC mode.

       
      Step 6show running-config


      Example: 
      Switch# show running-config
       

      Verifies your entries.

       
      Step 7copy running-config startup-config


      Example: 
      Switch# copy running-config startup-config
       

      (Optional) Saves your entries in the configuration file.

       

      Requesting Source Information from an MSDP Peer

      If you want a new member of a group to learn the active multicast sources in a connected PIM sparse-mode domain that are sending to a group, perform this task for the switch to send SA request messages to the specified MSDP peer when a new member joins a group. The peer replies with the information in its SA cache. If the peer does not have a cache configured, this command has no result. Configuring this feature reduces join latency but sacrifices memory.

      This task is optional.

         Command or ActionPurpose
        Step 1configure terminal


        Example: 
        Switch# configure terminal
         

        Enters global configuration mode.

         
        Step 2ip msdp sa-request {ip-address | name}


        Example: 
        Switch(config)# ip msdp sa-request 171.69.1.1
         

        Configure the switch to send SA request messages to the specified MSDP peer.

        For ip-address | name, enter the IP address or name of the MSDP peer from which the local switch requests SA messages when a new member for a group becomes active.

        Repeat the command for each MSDP peer that you want to supply with SA messages.

         
        Step 3end


        Example: 
        Switch(config)# end
         

        Returns to privileged EXEC mode.

         
        Step 4show running-config


        Example: 
        Switch# show running-config
         

        Verifies your entries.

         
        Step 5copy running-config startup-config


        Example: 
        Switch# copy running-config startup-config
         

        (Optional) Saves your entries in the configuration file.

         

        Controlling Source Information that Your Switch Originates

        You can control the multicast source information that originates with your switch:

        • Sources you advertise (based on your sources)
        • Receivers of source information (based on knowing the requestor)

        For more information, see the Redistributing Sources and the Filtering Source-Active Request Messages.

        Redistributing Sources

        SA messages originate on RPs to which sources have registered. By default, any source that registers with an RP is advertised. The A flag is set in the RP when a source is registered, which means the source is advertised in an SA unless it is filtered.

        This task is optional.

           Command or ActionPurpose
          Step 1configure terminal


          Example: 
          Switch# configure terminal
           

          Enters global configuration mode.

           
          Step 2ip msdp redistribute [list access-list-name] [asn aspath-access-list-number] [route-map map]


          Example: 
          Switch(config)# ip msdp redistribute list 21
           

          Configures which (S,G) entries from the multicast routing table are advertised in SA messages.

          By default, only sources within the local domain are advertised.

          • (Optional) list access-list-name— Enters the name or number of an IP standard or extended access list. The range is 1 to 99 for standard access lists and 100 to 199 for extended lists. The access list controls which local sources are advertised and to which groups they send.
          • (Optional) asn aspath-access-list-number—Enters the IP standard or extended access list number in the range 1 to 199. This access list number must also be configured in the ip as-path access-list command.
          • (Optional) route-map map—Enters the IP standard or extended access list number in the range 1 to 199. This access list number must also be configured in the ip as-path access-list command.

          The switch advertises (S,G) pairs according to the access list or autonomous system path access list.

           
          Step 3Use one of the following:
          • access-listaccess-list-number { deny | permit } source [ source-wildcard ]
          • access-listaccess-list-number { deny | permit } protocol source source-wildcard destination destination-wildcard


          Example: 
          Switch(config)# access list 21 permit 194.1.22.0

          or 

          Switch(config)# access list 21 permit ip 194.1.22.0 1.1.1.1 194.3.44.0 1.1.1.1
           

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

          or

          Creates an IP extended access list, repeating the command as many times as necessary.

          • access-list-number—Enters the same number created in Step 2. The range is 1 to 99 for standard access lists and 100 to 199 for extended lists.
          • deny—Denies access if the conditions are matched. The permit keyword permits access if the conditions are matched.
          • protocol—Enters ip as the protocol name.
          • source—Enters the number of the network or host from which the packet is being sent.
          • source-wildcard—Enters the wildcard bits in dotted decimal notation to be applied to the source. Place ones in the bit positions that you want to ignore.
          • destination—Enters the number of the network or host to which the packet is being sent.
          • destination-wildcard—Enters the wildcard bits in dotted decimal notation to be applied to the destination. 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 4end


          Example: 
          Switch(config)# end
           

          Returns to privileged EXEC mode.

           
          Step 5show running-config


          Example: 
          Switch# show running-config
           

          Verifies your entries.

           
          Step 6copy running-config startup-config


          Example: 
          Switch# copy running-config startup-config
           

          (Optional) Saves your entries in the configuration file.

           

          Filtering Source-Active Request Messages

          By default, only switches that are caching SA information can respond to SA requests. By default, such a switch honors all SA request messages from its MSDP peers and supplies the IP addresses of the active sources.

          However, you can configure the switch to ignore all SA requests from an MSDP peer. You can also honor only those SA request messages from a peer for groups described by a standard access list. If the groups in the access list pass, SA request messages are accepted. All other such messages from the peer for other groups are ignored.

          This task is optional.

             Command or ActionPurpose
            Step 1configure terminal


            Example: 
            Switch# configure terminal
             

            Enters global configuration mode.

             
            Step 2Use one of the following:
            • ip msdp filter-sa-request { ip-address | name }
            • ip msdp filter-sa-request { ip-address | name } list access-list-number


            Example: 
            Switch(config)# ip msdp filter sa-request 171.69.2.2
             

            Filters all SA request messages from the specified MSDP peer.

            or

            Filters SA request messages from the specified MSDP peer for groups that pass the standard access list. The access list describes a multicast group address. The range for the access-list-number is 1 to 99.

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


            Example: 
            Switch(config)# access-list 1 permit 192.4.22.0 0.0.0.255
             

            Creates an IP 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. 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.

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

             
            Step 4end


            Example: 
            Switch(config)# end
             

            Returns to privileged EXEC mode.

             
            Step 5show running-config


            Example: 
            Switch# show running-config
             

            Verifies your entries.

             
            Step 6copy running-config startup-config


            Example: 
            Switch# copy running-config startup-config
             

            (Optional) Saves your entries in the configuration file.

             

            Controlling Source Information that Your Switch Forwards

            By default, the switch forwards all SA messages it receives to all its MSDP peers. However, you can prevent outgoing messages from being forwarded to a peer by using a filter or by setting a time-to-live (TTL) value.

            Using a Filter

            By creating a filter, you can perform one of these actions:

            • Filter all source/group pairs
            • Specify an IP extended access list to pass only certain source/group pairs
            • Filter based on match criteria in a route map

            This task is optional.

               Command or ActionPurpose
              Step 1configure terminal


              Example: 
              Switch# configure terminal
               

              Enters global configuration mode.

               
              Step 2Use one of the following:
              • ip msdp sa-filter out
                { ip-address | name }
              • ip msdp sa-filter out
                { ip-address | name } list access-list-number
              • ip msdp sa-filter out
                { ip-address | name } route-map map-tag


              Example: 
              Switch(config)# ip msdp sa-filter out switch.cisco.com

              or 

              Switch(config)# ip msdp sa-filter out list 100

              or 

              Switch(config)# ip msdp sa-filter out switch.cisco.com route-map 22
               
              • Filters all SA messages to the specified MSDP peer.
              • Passes only those SA messages that pass the IP extended access list to the specified peer. The range for the extended access-list-number is 100 to 199. If both the list and the route-map keywords are used, all conditions must be true to pass any (S,G) pair in outgoing SA messages.
              • Passes only those SA messages that meet the match criteria in the route map map-tag to the specified MSDP peer. If all match criteria are true, a permit from the route map passes routes through the filter. A deny filters routes.
               
              Step 3access-list access-list-number {deny | permit} protocol source source-wildcard destination destination-wildcard


              Example: 
              Switch(config)# access list 100 permit ip 194.1.22.0 1.1.1.1 194.3.44.0 1.1.1.1
               

              (Optional) Creates an IP extended access list, repeating the command as many times as necessary.

              • For access-list-number, enter the 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 protocol, enter ip as the protocol name.
              • For source, enter the number of the network or host from which the packet is being sent.
              • 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.
              • For destination, enter the number of the network or host to which the packet is being sent.
              • For destination-wildcard, enter the wildcard bits in dotted decimal notation to be applied to the destination. 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 4end


              Example: 
              Switch(config)# end
               

              Returns to privileged EXEC mode.

               
              Step 5show running-config


              Example: 
              Switch# show running-config
               

              Verifies your entries.

               
              Step 6copy running-config startup-config


              Example: 
              Switch# copy running-config startup-config
               

              (Optional) Saves your entries in the configuration file.

               

              Using TTL to Limit the Multicast Data Sent in SA Messages

              You can use a TTL value to control what data is encapsulated in the first SA message for every source. Only multicast packets with an IP-header TTL greater than or equal to the ttl argument are sent to the specified MSDP peer. For example, you can limit internal traffic to a TTL of 8. If you want other groups to go to external locations, you must send those packets with a TTL greater than 8.

              This task is optional.

                 Command or ActionPurpose
                Step 1configure terminal


                Example: 
                Switch# configure terminal
                 

                Enters global configuration mode.

                 
                Step 2ip msdp ttl-threshold {ip-address | name} ttl


                Example: 
                Switch(config)# ip msdp ttl-threshold switch.cisco.com 0
                 

                Limits which multicast data is encapsulated in the first SA message to the specified MSDP peer.

                • For ip-address | name, enter the IP address or name of the MSDP peer to which the TTL limitation applies.
                • For ttl, enter the TTL value. The default is 0, which means all multicast data packets are forwarded to the peer until the TTL is exhausted. The range is 0 to 255.
                 
                Step 3end


                Example: 
                Switch(config)# end
                 

                Returns to privileged EXEC mode.

                 
                Step 4show running-config


                Example: 
                Switch# show running-config
                 

                Verifies your entries.

                 
                Step 5copy running-config startup-config


                Example: 
                Switch# copy running-config startup-config
                 

                (Optional) Saves your entries in the configuration file.

                 

                Controlling Source Information that Your Switch Receives

                By default, the switch receives all SA messages that its MSDP RPF peers send to it. However, you can control the source information that you receive from MSDP peers by filtering incoming SA messages. In other words, you can configure the switch to not accept them.

                You can perform one of these actions:

                • Filter all incoming SA messages from an MSDP peer
                • Specify an IP extended access list to pass certain source/group pairs
                • Filter based on match criteria in a route map

                This task is optional.

                   Command or ActionPurpose
                  Step 1configure terminal


                  Example: 
                  Switch# configure terminal
                   

                  Enters global configuration mode.

                   
                  Step 2Use one of the following:
                  • ip msdp sa-filter in
                    { ip-address | name }
                  • ip msdp sa-filter in
                    { ip-address | name } list access-list-number
                  • ip msdp sa-filter in
                    { ip-address | name } route-map map-tag


                  Example: 
                  Switch(config)# ip msdp sa-filter in switch.cisco.com

                  or 

                  Switch(config)# ip msdp sa-filter in list 100

                  or 

                  Switch(config)# ip msdp sa-filter in switch.cisco.com route-map 22
                   
                  • Filters all SA messages to the specified MSDP peer.
                  • Passes only those SA messages from the specified peer that pass the IP extended access list. The range for the extended access-list-number is 100 to 199. If both the list and the route-map keywords are used, all conditions must be true to pass any (S,G) pair in outgoing SA messages.
                  • Passes only those SA messages from the specified MSDP peer that meet the match criteria in the route map map-tag. If all match criteria are true, a permit from the route map passes routes through the filter. A deny filters routes.
                   
                  Step 3access-list access-list-number {deny | permit} protocol source source-wildcard destination destination-wildcard


                  Example: 
                  Switch(config)# access list 100 permit ip 194.1.22.0 1.1.1.1 194.3.44.0 1.1.1.1
                   

                  (Optional) Creates an IP extended access list, repeating the command as many times as necessary.

                  • access-list-number, enter the 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 protocol, enter ip as the protocol name.
                  • For source, enter the number of the network or host from which the packet is being sent.
                  • 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.
                  • For destination, enter the number of the network or host to which the packet is being sent.
                  • For destination-wildcard, enter the wildcard bits in dotted decimal notation to be applied to the destination. 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 4end


                  Example: 
                  Switch(config)# end
                   

                  Returns to privileged EXEC mode.

                   
                  Step 5show running-config


                  Example: 
                  Switch# show running-config
                   

                  Verifies your entries.

                   
                  Step 6copy running-config startup-config


                  Example: 
                  Switch# copy running-config startup-config
                   

                  (Optional) Saves your entries in the configuration file.

                   

                  Configuring an MSDP Mesh Group

                  Perform this optional task to configure an MSDP mesh group.


                  Note

                  You can configure multiple mesh groups per device.

                  SUMMARY STEPS

                    1.    enable

                    2.    configure terminal

                    3.    ip msdp mesh-group mesh-name {peer-address | peer-name}

                    4.    Repeat Step 3 to add MSDP peers as members of the mesh group.

                    5.    exit

                    6.    show running-config

                    7.    copy running-config startup-config


                  DETAILED STEPS
                     Command or ActionPurpose
                    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 ip msdp mesh-group mesh-name {peer-address | peer-name}


                    Example: 
                    Switch(config)# ip msdp mesh-group peermesh
                     

                    Configures an MSDP mesh group and indicates that an MSDP peer belongs to that mesh group.

                    Note   

                    All MSDP peers on a device that participate in a mesh group must be fully meshed with all other MSDP peers in the group. Each MSDP peer on each device must be configured as a peer using the ip msdp peer command and also as a member of the mesh group using the ip msdp mesh-group command.

                     
                    Step 4 Repeat Step 3 to add MSDP peers as members of the mesh group.  

                    --

                     
                    Step 5 exit


                    Example: 
                    Switch(config)# exit
                     

                    Exits global configuration mode and returns to privileged EXEC mode.

                     
                    Step 6show running-config


                    Example: 
                    
Switch# show running-config
                     

                    Verifies your entries.

                     
                    Step 7copy running-config startup-config


                    Example: 
                    Switch# copy running-config startup-config
                     

                    (Optional) Saves your entries in the configuration file.

                     

                    Shutting Down an MSDP Peer

                    Perform this optional task to shut down an MSDP peer.

                    If you are configuring several MSDP peers and you do not want any of the peers to go active until you have finished configuring all of them, you can shut down each peer, configure each peer, and later bring each peer up. You might also want to shut down an MSDP session without losing the configuration for that MSDP peer.


                    Note

                    When an MSDP peer is shut down, the TCP connection is terminated and not restarted until the peer is brought back up using the no ip msdp shutdown command (for the specified peer).

                    Before You Begin

                    MSDP is running and the MSDP peers must be configured.

                    SUMMARY STEPS

                      1.    enable

                      2.    configure terminal

                      3.    ip msdp shutdown {peer-name | peer-address}

                      4.    Repeat Step 3 to shut down additional MSDP peers.

                      5.    end

                      6.    show running-config

                      7.    copy running-config startup-config


                    DETAILED STEPS
                       Command or ActionPurpose
                      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 ip msdp shutdown {peer-name | peer-address}


                      Example: 
                      Switch(config)# ip msdp shutdown 192.168.1.3
                       

                      Administratively shuts down the specified MSDP peer.

                       
                      Step 4 Repeat Step 3 to shut down additional MSDP peers.  

                      --

                       
                      Step 5 end


                      Example: 
                      Switch(config)# end
                       

                      Exits global configuration mode and returns to privileged EXEC mode.

                       
                      Step 6show running-config


                      Example: 
                      
Switch# show running-config
                       

                      Verifies your entries.

                       
                      Step 7copy running-config startup-config


                      Example: 
                      Switch# copy running-config startup-config
                       

                      (Optional) Saves your entries in the configuration file.

                       

                      Including a Bordering PIM Dense-Mode Region in MSDP

                      You can configure MSDP on a switch that borders a PIM sparse-mode region with a dense-mode region. By default, active sources in the dense-mode region do not participate in MSDP.


                      Note

                      We do not recommend using the ip msdp border sa-address global configuration command. It is better to configure the border router in the sparse-mode domain to proxy-register sources in the dense-mode domain to the RP of the sparse-mode domain and have the sparse-mode domain use standard MSDP procedures to advertise these sources.

                      The ip msdp originator-id global configuration command also identifies an interface to be used as the RP address. If both the ip msdp border sa-address and the ip msdp originator-id global configuration commands are configured, the address derived from the ip msdp originator-id command specifies the RP address.

                      This task is optional.

                         Command or ActionPurpose
                        Step 1configure terminal


                        Example: 
                        Switch# configure terminal
                         

                        Enters global configuration mode.

                         
                        Step 2ip msdp border sa-address interface-id


                        Example: 
                        Switch(config)# ip msdp border sa-address 0/1
                         

                        Configures the switch on the border between a dense-mode and sparse-mode region to send SA messages about active sources in the dense-mode region.

                        For interface-id, specifies the interface from which the IP address is derived and used as the RP address in SA messages.

                        The IP address of the interface is used as the Originator-ID, which is the RP field in the SA message.

                         
                        Step 3ip msdp redistribute [list access-list-name] [asn aspath-access-list-number] [route-map map]


                        Example: 
                        Switch(config)# ip msdp redistribute list 100
                         

                        Configures which (S,G) entries from the multicast routing table are advertised in SA messages.

                        For more information, see the Redistributing Sources.

                         
                        Step 4end


                        Example: 
                        Switch(config)# end
                         

                        Returns to privileged EXEC mode.

                         
                        Step 5show running-config


                        Example: 
                        Switch# show running-config
                         

                        Verifies your entries.

                         
                        Step 6copy running-config startup-config


                        Example: 
                        Switch# copy running-config startup-config
                         

                        (Optional) Saves your entries in the configuration file.

                         

                        Configuring an Originating Address other than the RP Address

                        Perform this optional task to allow an MSDP speaker that originates an SA message to use the IP address of its interface as the RP address in the SA message.

                        You can also change the originator ID for any one of the following reasons:
                        • If you configure multiple devices in an MSDP mesh group for Anycast RP.
                        • If you have a device that borders a PIM-SM domain and a PIM-DM domain. If a device borders a PIM-SM domain and a PIM-DM domain and you want to advertise active sources within the PIM-DM domain, configure the RP address in SA messages to be the address of the originating device’s interface.
                        Before You Begin

                        MSDP is enabled and the MSDP peers are configured. For more information about configuring MSDP peers, see the Configuring an MSDP Peer section.

                        SUMMARY STEPS

                          1.    enable

                          2.    configure terminal

                          3.    ip msdp originator-id

                          4.    exit

                          5.    show running-config

                          6.    copy running-config startup-config


                        DETAILED STEPS
                           Command or ActionPurpose
                          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 ip msdp originator-id


                          Example: 
                          Switch(config)# ip msdp originator-id ethernet 1
                           

                          Configures the RP address in SA messages to be the address of the originating device’s interface.

                           
                          Step 4 exit


                          Example: 
                          Switch(config)# exit
                           

                          Exits global configuration mode and returns to privileged EXEC mode.

                           
                          Step 5show running-config


                          Example: 
                          
Switch# show running-config
                           

                          Verifies your entries.

                           
                          Step 6copy running-config startup-config


                          Example: 
                          Switch# copy running-config startup-config
                           

                          (Optional) Saves your entries in the configuration file.

                           

                          Monitoring and Maintaining MSDP

                          Monitoring MSDP

                          Perform this optional task to monitor MSDP SA messages, peers, state, and peer status.

                          SUMMARY STEPS

                            1.    enable

                            2.    debug ip msdp [peer-address | peer-name] [detail] [routes]

                            3.    debug ip msdp resets

                            4.    show ip msdp count [as-number]

                            5.    show ip msdp peer [peer-address | peer-name]

                            6.    show ip msdp sa-cache [group-address | source-address | group-name | source-name] [as-number]

                            7.    show ip msdp summary


                          DETAILED STEPS
                            Step 1   enable


                            Example:
                            Device# enable

                            Enables privileged EXEC mode.

                            • Enter your password if prompted.
                            Step 2   debug ip msdp [peer-address | peer-name] [detail] [routes]

                            Use this command to debug MSDP activity.

                            Use the optional peer-address or peer-name argument to specify for which peer debug events are logged.

                            The following is sample output from the debug ip msdp command:



                            Example:
                            Device# debug ip msdp
MSDP debugging is on
Device#
MSDP: 224.150.44.254: Received 1388-byte message from peer
MSDP: 224.150.44.254: SA TLV, len: 1388, ec: 115, RP: 172.31.3.92 
MSDP: 224.150.44.254: Peer RPF check passed for 172.31.3.92, used EMBGP peer
MSDP: 224.150.44.250: Forward 1388-byte SA to peer
MSDP: 224.150.44.254: Received 1028-byte message from peer
MSDP: 224.150.44.254: SA TLV, len: 1028, ec: 85, RP: 172.31.3.92 
MSDP: 224.150.44.254: Peer RPF check passed for 172.31.3.92, used EMBGP peer
MSDP: 224.150.44.250: Forward 1028-byte SA to peer
MSDP: 224.150.44.254: Received 1388-byte message from peer
MSDP: 224.150.44.254: SA TLV, len: 1388, ec: 115, RP: 172.31.3.111 
MSDP: 224.150.44.254: Peer RPF check passed for 172.31.3.111, used EMBGP peer
MSDP: 224.150.44.250: Forward 1388-byte SA to peer
MSDP: 224.150.44.250: Received 56-byte message from peer
MSDP: 224.150.44.250: SA TLV, len: 56, ec: 4, RP: 192.168.76.241 
MSDP: 224.150.44.250: Peer RPF check passed for 192.168.76.241, used EMBGP peer
MSDP: 224.150.44.254: Forward 56-byte SA to peer
MSDP: 224.150.44.254: Received 116-byte message from peer
MSDP: 224.150.44.254: SA TLV, len: 116, ec: 9, RP: 172.31.3.111 
MSDP: 224.150.44.254: Peer RPF check passed for 172.31.3.111, used EMBGP peer
MSDP: 224.150.44.250: Forward 116-byte SA to peer
MSDP: 224.150.44.254: Received 32-byte message from peer
MSDP: 224.150.44.254: SA TLV, len: 32, ec: 2, RP: 172.31.3.78 
MSDP: 224.150.44.254: Peer RPF check passed for 172.31.3.78, used EMBGP peer
MSDP: 224.150.44.250: Forward 32-byte SA to peer
                            Step 3   debug ip msdp resets

                            Use this command to debug MSDP peer reset reasons.



                            Example:
                            Device# debug ip msdp resets
                            Step 4   show ip msdp count [as-number]

                            Use this command to display the number of sources and groups originated in MSDP SA messages and the number of SA messages from an MSDP peer in the SA cache. The ip msdp cache-sa-state command must be configured for this command to produce any output.

                            The following is sample output from the show ip msdp countcommand:



                            Example:
                            Device# show ip msdp count
SA State per Peer Counters, <Peer>: <# SA learned>
    192.168.4.4: 8
SA State per ASN Counters, <asn>: <# sources>/<# groups>
    Total entries: 8
    ?: 8/8
                            Step 5   show ip msdp peer [peer-address | peer-name]

                            Use this command to display detailed information about MSDP peers.

                            Use the optional peer-address or peer-name argument to display information about a particular peer.

                            The following is sample output from the show ip msdp peercommand:



                            Example:
                            Device# show ip msdp peer 192.168.4.4
MSDP Peer 192.168.4.4 (?), AS 64512 (configured AS)
  Connection status:
    State: Up, Resets: 0, Connection source: Loopback0 (2.2.2.2)
    Uptime(Downtime): 00:07:55, Messages sent/received: 8/18
    Output messages discarded: 0
    Connection and counters cleared 00:08:55 ago
  SA Filtering:
    Input (S,G) filter: none, route-map: none
    Input RP filter: none, route-map: none
    Output (S,G) filter: none, route-map: none
    Output RP filter: none, route-map: none
  SA-Requests: 
    Input filter: none
  Peer ttl threshold: 0
  SAs learned from this peer: 8
  Input queue size: 0, Output queue size: 0
  MD5 signature protection on MSDP TCP connection: not enabled
                            Step 6   show ip msdp sa-cache [group-address | source-address | group-name | source-name] [as-number]

                            Use this command to display the (S, G) state learned from MSDP peers.

                            The following is sample output from the show ip msdp sa-cachecommand:



                            Example:
                            Device# show ip msdp sa-cache
MSDP Source-Active Cache - 8 entries
(10.44.44.5, 239.232.1.0), RP 192.168.4.4, BGP/AS 64512, 00:01:20/00:05:32, Peer 192.168.4.4
(10.44.44.5, 239.232.1.1), RP 192.168.4.4, BGP/AS 64512, 00:01:20/00:05:32, Peer 192.168.4.4
(10.44.44.5, 239.232.1.2), RP 192.168.4.4, BGP/AS 64512, 00:01:19/00:05:32, Peer 192.168.4.4
(10.44.44.5, 239.232.1.3), RP 192.168.4.4, BGP/AS 64512, 00:01:19/00:05:32, Peer 192.168.4.4
(10.44.44.5, 239.232.1.4), RP 192.168.4.4, BGP/AS 64512, 00:01:19/00:05:32, Peer 192.168.4.4
(10.44.44.5, 239.232.1.5), RP 192.168.4.4, BGP/AS 64512, 00:01:19/00:05:32, Peer 192.168.4.4
(10.44.44.5, 239.232.1.6), RP 192.168.4.4, BGP/AS 64512, 00:01:19/00:05:32, Peer 192.168.4.4
(10.44.44.5, 239.232.1.7), RP 192.168.4.4, BGP/AS 64512, 00:01:19/00:05:32, Peer 192.168.4.4
                            Step 7   show ip msdp summary

                            Use this command to display MSDP peer status.

                            The following is sample output from the show ip msdp summary command:



                            Example:
                            Device# show ip msdp summary
MSDP Peer Status Summary
Peer Address     AS    State    Uptime/  Reset SA    Peer Name
                                Downtime Count Count
192.168.4.4      4     Up       00:08:05 0     8     ?

                            Clearing MSDP Connections Statistics and SA Cache Entries

                            Perform this optional task to clear MSDP connections, statistics, and SA cache entries.

                            SUMMARY STEPS

                              1.    enable

                              2.    clear ip msdp peer [peer-address | peer-name]

                              3.    clear ip msdp statistics [peer-address | peer-name]

                              4.    clear ip msdp sa-cache [group-address]


                            DETAILED STEPS
                               Command or ActionPurpose
                              Step 1 enable


                              Example:
                              Device> enable
                               

                              Enables privileged EXEC mode.

                              • Enter your password if prompted.
                               
                              Step 2 clear ip msdp peer [peer-address | peer-name]


                              Example:
                              Device# clear ip msdp peer
                               

                              Clears the TCP connection to the specified MSDP peer and resets all MSDP message counters.

                               
                              Step 3 clear ip msdp statistics [peer-address | peer-name]


                              Example:
                              Device# clear ip msdp statistics
                               

                              Clears the statistics counters for the specified MSDP peer and resets all MSDP message counters.

                               
                              Step 4 clear ip msdp sa-cache [group-address]


                              Example:
                              Device# clear ip msdp sa-cache
                               

                              Clears SA cache entries.

                              • If the clear ip msdp sa-cache is specified with the optional group-address argument or source-addressargument, all SA cache entries are cleared.
                              • Use the optional group-address argument to clear all SA cache entries associated with a specific group.
                               

                              Configuration Examples for Configuring MSDP

                              Configuring a Default MSDP Peer: Example

                              This example shows a partial configuration of Router A and Router C in . Each of these ISPs have more than one customer (like the customer in ) who use default peering (no BGP or MBGP). In that case, they might have similar configurations. That is, they accept SAs only from a default peer if the SA is permitted by the corresponding prefix list.

                              Router A

                              Router(config)# ip msdp default-peer 10.1.1.1
Router(config)# ip msdp default-peer 10.1.1.1 prefix-list site-a
Router(config)# ip prefix-list site-b permit 10.0.0.0/1

                              Router C

                              Router(config)# ip msdp default-peer 10.1.1.1 prefix-list site-a 
Router(config)# ip prefix-list site-b permit 10.0.0.0/1

                              Caching Source-Active State: Example

                              This example shows how to enable the cache state for all sources in 171.69.0.0/16 sending to groups 224.2.0.0/16:

                              Switch(config)# ip msdp cache-sa-state 100
Switch(config)# access-list 100 permit ip 171.69.0.0 0.0.255.255 224.2.0.0 0.0.255.255

                              Requesting Source Information from an MSDP Peer: Example

                              This example shows how to configure the switch to send SA request messages to the MSDP peer at 171.69.1.1:

                              Switch(config)# ip msdp sa-request 171.69.1.1

                              Controlling Source Information that Your Switch Originates: Example

                              This example shows how to configure the switch to filter SA request messages from the MSDP peer at 171.69.2.2. SA request messages from sources on network 192.4.22.0 pass access list 1 and are accepted; all others are ignored.

                              Switch(config)# ip msdp filter sa-request 171.69.2.2 list 1
Switch(config)# access-list 1 permit 192.4.22.0 0.0.0.255

                              Controlling Source Information that Your Switch Forwards: Example

                              This example shows how to allow only (S,G) pairs that pass access list 100 to be forwarded in an SA message to the peer named switch.cisco.com:

                              Switch(config)# ip msdp peer switch.cisco.com connect-source gigabitethernet1/0/1
Switch(config)# ip msdp sa-filter out switch.cisco.com list 100
Switch(config)# access-list 100 permit ip 171.69.0.0 0.0.255.255 224.20 0 0.0.255.255

                              Controlling Source Information that Your Switch Receives: Example

                              This example shows how to filter all SA messages from the peer named switch.cisco.com:

                              Switch(config)# ip msdp peer switch.cisco.com connect-source gigabitethernet1/0/1
Switch(config)# ip msdp sa-filter in switch.cisco.com

                              Example: Configuring MSDP Mesh Groups

                              The following example shows how to configure three devices to be fully meshed members of an MSDP mesh group:

                              Device A Configuration

                              ip msdp peer 10.2.2.2
ip msdp peer 10.3.3.3
ip msdp mesh-group test-mesh-group 10.2.2.2
ip msdp mesh-group test-mesh-group 10.3.3.3

                              Device B Configuration

                              ip msdp peer 10.1.1.1
ip msdp peer 10.3.3.3
ip msdp mesh-group test-mesh-group 10.1.1.1
ip msdp mesh-group test-mesh-group 10.3.3.3

                              Device C Configuration

                              ip msdp peer 10.1.1.1
ip msdp peer 10.2.2.2
ip msdp mesh-group test-mesh-group 10.1.1.1
ip msdp mesh-group test-mesh-group 10.2.2.2

                              Requesting Source Information from an MSDP Peer: Example

                              This example shows how to configure the switch to send SA request messages to the MSDP peer at 171.69.1.1:

                              Switch(config)# ip msdp sa-request 171.69.1.1

                              Additional References

                              Related Documents

                              Related Topic Document Title

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

                              Command Reference, Cisco Release 15.2(2)E (Industrial Ethernet 3010 Switch)

                              Cisco IOS commands

                              Cisco IOS Master Commands List, All Releases

                              IP multicast commands

                              Cisco IOS IP Multicast Command Reference

                              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 RFC

                              Standard/RFC

                              Title

                              RFC 3618

                              Multicast Source Discovery Protocol

                              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