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Table Of Contents
Multicast Source Discovery Protocol
Supported Standards, MIBs, and RFCs
Requesting Source Information from an MSDP Peer
Controlling Source Information Your Router Originates
Filtering Source-Active Request Messages
Controlling Source Information Your Router Forwards
Using TTL to Limit the Multicast Data Sent in SA Messages
Controlling Source Information Your Router Receives
Configuring a Default MSDP Peer
Configuring an MSDP Mesh Group
Including a Bordering PIM Dense-Mode Region in MSDP
Configuring an Originating Address Other Than the RP Address
Monitoring and Maintaining MSDP
Multicast Source Discovery Protocol
This feature module describes the Multicast Source Discovery Protocol feature. It includes information on the benefits of the new feature, supported platforms, related documents, and so forth.
This document includes the following sections:
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Supported Standards, MIBs, and RFCs
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Feature Overview
Multicast Source Discovery Protocol (MSDP) is a mechanism to connect multiple PIM sparse-mode (SM) domains. MSDP allows multicast sources for a group to be known to all rendezvous point(s) (RPs) in different domains. Each PIM-SM domain uses its own RPs and need not depend on RPs in other domains. An RP runs MSDP over TCP to discover multicast sources in other domains.
An RP in a PIM-SM domain has an MSDP peering relationship with MSDP-enabled routers in another domain. The peering relationship occurs over a TCP connection, where primarily a list of sources sending to multicast groups is exchanged. The TCP connections between RPs are achieved by the underlying routing system. The receiving RP uses the source lists to establish a source path.
The purpose of this topology is to have domains discover multicast sources in other domains. If the multicast sources are of interest to a domain that has receivers, multicast data is delivered over the normal, source-tree building mechanism in PIM-SM.
MSDP is also used to announce sources sending to a group. These announcements must originate at the domain's RP.
MSDP depends heavily on (M)BGP for interdomain operation. It is recommended that you run MSDP in RPs in your domain that are RPs for sources sending to global groups to be announced to the internet.
How MSDP Works
illustrates MSDP operating between two MSDP peers. PIM uses MSDP as the standard mechanism to register a source with the RP of a domain.
When MSDP is configured, the following sequence occurs. When a source's first data packet is registered by the first-hop router, that same data packet is decapsulated by the RP and forwarded down the shared tree. That packet is also re-encapsulated in a Source-Active (SA) message that is immediately forwarded to all MSDP peers. The SA message identifies the source, the group the source is sending to, and the RP's own address or the originator ID, if configured. If the peer is an RP and has a member of that multicast group, the data packet is decapsulated and forwarded down the shared-tree in the remote domain.
The PIM designated router (DR) directly connected to the source sends the data encapsulated in a PIM Register message to the RP in the domain.
Note
Each MSDP peer receives and forwards the SA message away from the originating RP to achieve "peer-RPF flooding." The concept of peer-RPF flooding is with respect to forwarding SA messages. The router examines the BGP or MBGP routing table to determine which peer is the next hop toward the originating RP of the SA message. Such a peer is called an "RPF peer" (Reverse-Path Forwarding peer). The router forwards the message to all MSDP peers other than the RPF peer.
If the MSDP peer receives the same SA message from a non-RPF peer toward the originating RP, it drops the message. Otherwise, it forwards the message on to all its MSDP peers.
When an RP for a domain receives an SA message from an MSDP peer, it determines if it has any group members interested in the group the SA message describes. If the (*,G) entry exists with a nonempty outgoing interface list, the domain is interested in the group, and the RP triggers an (S,G) join toward the source.
Figure 1 MSDP Running Between RP Peers
Benefits
MSDP has the following benefits:
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Supported Platforms
MSDP operates on all Cisco IOS platforms that run Cisco IOS Release 11.1 CC, 12.0(5)S, or 12.0(7)T.
Prerequisites
Before configuring MSDP, the addresses of all MSDP peers must be known in BGP or MBGP. If that does not occur, you must configure MSDP default peering when you configure MSDP.
Supported Standards, MIBs, and RFCs
MIBs
No new or modified MIBs are supported by this feature.
For descriptions of supported MIBs and how to use MIBs, see the Cisco MIB web site on CCO at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.
RFCs
None
Standards
This feature supports Internet Engineering Task Force draft Multicast Source Discovery Protocol (MSDP).
Configuration Tasks
To configure an MSDP peer and various MSDP options, perform the following tasks. The first task is required; the remaining are optional.
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Configuring an MSDP Peer
You enable MSDP by configuring an MSDP peer to the local router.
Note
To configure an MSDP peer, use the following commands in global configuration mode. The second command is optional.
Caching Source-Active State
By default, the router does not cache source/group pairs from received SA messages. Once the router forwards the MSDP Source-Active information, it does not store it in memory. Therefore, if a member joins a group soon after a Source-Active message is received by the local RP, that member will have to wait until the next SA message to hear about the source. This delay is known as join latency.
If you want to sacrifice some memory in exchange for reducing the latency of the source information, you can configure the router to cache Source-Active messages. To have the router cache source/group pairs, use the following command in global configuration mode
ip msdp cache-sa-state [list access-list-number]
Creates SA state (cache source/group pairs). Those pairs that pass the access list are cached.
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An alternative to caching the source-active state is to request source information from a peer, which is described in the section "Requesting Source Information from an MSDP Peer." If you cache the information, you don't need to trigger a request for it.
Requesting Source Information from an MSDP Peer
Local RPs can send Source-Active Requests and get immediate response for all active sources for a given group. By default, the router does not send any Source-Active Request messages to its MSDP peers when a new member joins a group and wants to receive multicast traffic. The new member just waits to receive the next periodic Source-Active message.
If you want a new member of a group to learn the current, active multicast sources in a connected PIM sparse-mode domain that are sending to a group, configure the router to send Source-Active Request messages to the specified MSDP peer when a new member joins a group. Doing so reduces join latency, but requires some memory.
Note that information can be requested only from caching peers.
To configure this feature, use the following command in global configuration mode
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Repeat the preceding command for each MSDP peer that you want to supply you with Source-Active messages.
An alternative to requesting source information is to cache the source-active state, which is described in the earlier section "Caching Source-Active State." If you cache the information, you don't need to trigger a request for it.
Controlling Source Information Your Router Originates
There are two ways to control the multicast source information that originates with your router. You can control the following:
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To control which sources you will advertise, see the section "Redistributing Sources" later in this document. To control whom you will provide source information to, see the section "Controlling Source Information Your Router Forwards."
Redistributing Sources
Source-Active messages are originated on RPs to which sources have registered. By default, any source that registers with an RP will be advertised. The "A flag" is set in the RP when a source is registered. This means the source will be advertised in an SA unless it is filtered with the command below.
To further restrict which registered sources are advertised, use the following command in global configuration mode. The access list or autonomous system path access list determines which (S,G) pairs are advertised
ip msdp redistribute [list access-list-name] [asn aspath-access-list-number] [route-map map]
Advertises (S,G) pairs that pass the access list or route map to other domains.
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Note
Filtering Source-Active Request Messages
By default, only routers that are caching Source-Active information can respond to Source-Active Reuqests. By default, such a router honors all Source-Active Request messages from its MSDP peers. That is, it will supply the IP addresses of the sources that are active.
However, you can configure the router to ignore all Source-Active Requests from an MSDP peer. Or, you can honor only those Source-Active Request messages from a peer for groups described by a standard access list. If the access list passes, Source-Active Request messages will be accepted. All other such messages from the peer for other groups will be ignored.
To configure one of these options, use the appropriate command in global configuration mode
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Controlling Source Information Your Router Forwards
By default, the router forwards all Source-Active messages it receives to all of 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). These methods are described in the following sections.
Using a Filter
By creating a filter, you can do one of the following:
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To apply a filter, use one of the following commands in global configuration mode
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Using TTL to Limit the Multicast Data Sent in SA Messages
You can use TTL to control what data will be encapsulated in the first SA message for every source. For example, you could limit internal traffic to a TTL of 8. If you want other groups to go to external locations, you would have to send those packets with a TTL greater than 8.
To establish a TTL threshold, use the following command in global configuration mode:
ip msdp ttl-threshold {ip-address | name} ttl
Limits which multicast data will be encapsulated in the first Source-Active message to the specified MSDP peer.
Controlling Source Information Your Router Receives
By default, the router receives all Source-Active messages its MSDP Reverse-Path Forwarding peers send to it. However, you can control the source information you receive from MSDP peers by filtering incoming Source-Active messages. In other words, you can configure the router not to accept them.
You can do one of the following:
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To apply a filter, use one of the following commands in global configuration mode
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Configuring a Default MSDP Peer
An MSDP peer of the local router is probably a BGP peer also. However, if you do not want to have or cannot have a BGP peer, you could define a default MSDP peer from which to accept all SA messages. The default MSDP peer must be a previously configured MSDP peer. Perform this task when you are not BGP- or MBGP-peering with an MSDP peer. If a single MSDP peer is configured, a router will always accept all SA messages sent to it from that peer.
illustrates a scenario where default MSDP peers might be used. In the figure, a customer who owns Router B is connected to the internet via two Internet Service Providers (ISPs), one who owns Router A and the other who owns Router C. They are not running BGP or MBGP between them. In order for the customer to learn about sources in the ISP's domain or in other domains, Router B identifies Router A as its default MSDP peer. Router B advertises SA messages to both Router A and Router C, but accepts SA messages either from Router A only or Router C only. If Router A is first in the configuration file, it will be used if it is up and running. If Router A isn't running, then and only then will Router B accept SA messages from Router C.
The ISP will also likely use a prefix list to define which prefixes it will accept from the customer's router. The customer will define multiple default peers, each having one or more prefixes associated with it.
The customer has two ISPs to use. He 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
Router B advertises SAs to Router A and Router C, but uses only Router A or Router C to accept SA messages. If Router A is first in the configuration file, it will be used if it is up and running. If Router A isn't running, then, and only then, will Router B accept SAs from Router 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 router 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.
To specify a default MSDP peer, use the following command in global configuration mode
ip msdp default-peer ip-address | name [prefix-list list]
Defines a default MSDP peer.
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See the section "Default MSDP Peer" for a sample configuration.
Configuring an MSDP Mesh Group
An MSDP mesh group is a group of MSDP speakers that have fully meshed MSDP connectivity between one another. Any SA messages received from a peer in a mesh group are not forwarded to other peers in the same mesh group. Thus, you reduce SA message flooding and simplify peer-RPF flooding. The command below is used when there are multiple RPs within a domain. It is especially used to transit SA messages across a domain.
You can configure multiple mesh groups (with different names) in a single router.
To create a mesh group, use the following command in global configuration mode for each MSDP peer in the group:
ip msdp mesh-group name {ip-address | name}
Configures an MSDP mesh group and indicates that an MSDP peer belongs to that mesh group.
Shutting Down an MSDP Peer
If you want to configure many MSDP commands for the same peer and you do not want the peer to go active, you can shut down the peer, configure it, and later bring it up.
You might also want to shut down an MSDP session without losing configuration information for the peer.
When in shutdown mode, the TCP connection is terminated and not restarted.
To shut down a peer, use the following command in global configuration mode:
ip msdp shutdown {peer-name | peer address}
Administratively shuts down the specified MSDP peer.
Including a Bordering PIM Dense-Mode Region in MSDP
You might have a router that borders a PIM sparse-mode region with a dense-mode region. By default, sources in the dense-mode region are not included in MSDP. You could configure this border router to send SA messages for sources active in the dense-mode region. If you do so, it is very important to also configure the ip msdp redistribute command to apply to only local sources. This can result in (S, G) state remaining long after a source in the dense-mode domain has stopped sending.
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To configure the border router to send SA messages for sources active in the dense-mode region, use the following command in global configuration mode
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Configuring an Originating Address Other Than the RP Address
If you want to change the Originator ID for any reason, use the ip msdp originator-id command in this section. For example, you might change the Originator ID in one of these cases:
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To allow an MSDP speaker that originates a Source-Active message to use its interface's IP address as the RP address in the SA message, use the following command in global configuration mode
ip msdp originator-id type number
Configures the RP address in SA messages to be the address of the originating router's interface.
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Monitoring and Maintaining MSDP
To monitor MSDP Source-Active messages, peers, state, or peer status, use the following commands in EXEC mode:
To clear MSDP connections, statistics, or SA cache entries, use the following commands in EXEC mode:
Configuration Examples
This section contains the following MSDP configurations examples:
Default MSDP Peer
The following example is a partial configuration of Router A and Router C in . Each of these ISPs may have more than one customer like the customer in the figure who use default peering (no BGP or MBGP). In that case, they may have similar configurations. That is, they will only accept SAs from a default peer if the SA is permited by the corresponding prefix list.
Router A
ip msdp default-peer 10.1.1.1ip msdp default-peer 10.1.1.1 prefix-list site-a ge 32ip prefix-list site-b permit 10.0.0.0/8Router C
ip msdp default-peer 10.1.1.1 prefix-list site-a ge 32ip prefix-list site-b permit 10.0.0.0/8Logical RP
The following example configures a logical RP using an MSDP mesh-group. The four routers that are logical RPs are RouterA, RouterB, RouterC, and RouterD. RouterE is an MSDP border router that is not an RP. illustrates the logical RP environment in this example; the configurations for routers A, B and E follow the figure.
It is important to note the use of the loopback interface and how those host routes are advertised in OSPF. It is also important to carefully choose the OSPF router ID loopback so the ID does not use the logical RP address.
In this example, all the logical RPs are on the same LAN, but this is not typical. The host-route for the RP address is advertised throughout the domain and each PIM DR in the domain joins to the closest RP. The RPs each share (S,G) information with each other by sending SA messages. Each logical RP must use a separate Originator-ID.
Note there are two MSDP mesh-groups on RouterA. The routes for the loopback interfaces are in OSPF. Loopback 0 is the Router ID and is used as the connect-source/update-source for MBGP/MSDP. Loopback 10 is the same on all routers in the example.
All networks are 171.69.0.0. The RP address is 10.10.10.10 on Loopback 10 on all RPs. BGP connections are 192.168.1.x on Loopback 0. Loopback 0 is put into BGP with network 192.168.1.3 mask 255.255.255.255 nlri unicast multicast.
Figure 3 Logical RP using MSDP
RouterA
!hostname RouterA!ip routing!ip subnet-zeroip multicast-routing!!interface Loopback0ip address 192.168.1.2 255.255.255.255no shutdown!interface Loopback10ip address 10.10.10.10 255.255.255.255no ip directed-broadcastip pim sparse-dense-modeno shutdown!interface Ethernet1/2description LANethernet2ip address 171.69.2.2 255.255.255.0ip pim sparse-dense-modeno shutdown!interface Ethernet4/0/0description LANethernet3ip address 171.69.3.2 255.255.255.0ip pim sparse-dense-modeno shutdown!router ospf 10network 171.69.0.0 0.0.255.255 area 0network 10.10.10.10 0.0.0.0 area 0network 192.168.1.2 0.0.0.0 area 0!router bgp 1no synchronizationnetwork 171.69.0.0 nlri unicast multicastnetwork 192.168.1.2 mask 255.255.255.255 nlri unicast multicastneighbor 192.168.1.3 remote-as 1 nlri unicast multicastneighbor description routerBneighbor 192.168.1.3 next-hop-selfneighbor 192.168.1.3 update-source loopback0neighbor 192.168.1.4 remote-as 1 nlri unicast multicastneighbor description routerCneighbor 192.168.1.4 update-source loopback0neighbor 192.168.1.5 remote-as 1 nlri unicast multicastneighbor description routerDneighbor 192.168.1.5 next-hop-selfneighbor 192.168.1.5 update-source loopback0neighbor 192.168.1.6 remote-as 1 nlri unicast multicastneighbor description routerEneighbor 192.168.1.6 update-source Loopback0neighbor 192.168.1.6 next-hop-self!!ip msdp peer 192.168.1.3 connect-source loopback 0ip msdp peer 192.168.1.5 connect-source loopback 0ip msdp peer 192.168.1.4 connect-source loopback 0ip msdp peer 192.168.1.6 connect-source Loopback0ip msdp mesh-group inside-test 192.168.1.3ip msdp mesh-group inside-test 192.168.1.4ip msdp mesh-group inside-test 192.168.1.5ip msdp mesh-group outside-test 192.168.1.6ip msdp originator-id loopback0!ip classlessip pim send-rp-disc scope 10ip pim send-rp-anno loopback 10 scope 10!RouterB
!hostname RouterB!ip routing!ip multicast-routingip dvmrp route-limit 20000!interface Loopback0ip address 192.168.1.3 255.255.255.255no shutdown!interface Loopback10ip address 10.10.10.10 255.255.255.255ip pim sparse-dense-modeno shutdown!interface Ethernet2description LANethernet 0ip address 171.69.0.3 255.255.255.0ip pim sparse-dense-modeno shutdown!interface Ethernet3description LANethernet 2ip address 171.69.2.3 255.255.255.0ip pim sparse-dense!router ospf 10network 171.69.0.0 0.0.255.255 area 0network 10.10.10.10 0.0.0.0 area 0network 192.168.1.3 0.0.0.0 area 0!router bgp 1no synchronizationnetwork 171.69.0.0 nlri unicast multicastnetwork 192.168.1.3 mask 255.255.255.255 nlri unicast multicastneighbor 192.168.1.2 remote-as 1 nlri unicast multicastneighbor description routerAneighbor 192.168.1.2 update-source loopback0neighbor 192.168.1.4 remote-as 1 nlri unicast multicastneighbor description routerCneighbor 192.168.1.4 update-source loopback0neighbor 192.168.1.5 remote-as 1 nlri unicast multicastneighbor description routerDneighbor 192.168.1.5 update-source loopback0neighbor 192.168.1.5 soft-recon in!ip msdp peer 192.168.1.2 connect-source loopback 0ip msdp peer 192.168.1.5 connect-source loopback 0ip msdp peer 192.168.1.4 connect-source loopback 0ip msdp mesh-group inside-test 192.168.1.2ip msdp mesh-group inside-test 192.168.1.4ip msdp mesh-group inside-test 192.168.1.5ip msdp originator-id loopback0!ip classlessip pim send-rp-disc scope 10ip pim send-rp-anno loopback 10 scope 10!RouterE
!hostname RouterE!ip routing!ip subnet-zeroip routingip multicast-routingip dvmrp route-limit 20000!interface Loopback0ip address 192.168.1.6 255.255.255.255no shutdown!interface Ethernet2description LANethernet 3ip address 171.69.3.6 255.255.255.0ip pim sparse-dense-modeno shutdown!interface Ethernet5description LANethernet 6ip address 192.169.1.6 255.255.255.0ip pim sparse-dense-modeip multicast boundary 20no shutdown!router ospf 10network 171.69.0.0 0.0.255.255 area 0network 192.168.1.6 0.0.0.0 area 0default-information originate metric-type 1!router bgp 1no synchronizationnetwork 171.69.0.0 nlri unicast multicastnetwork 192.168.1.6 mask 255.255.255.255 nlri unicast multicastnetwork 192.168.1.0neighbor 192.168.1.2 remote-as 1 nlri unicast multicastneighbor 192.168.1.2 update-source Loopback0neighbor 192.168.1.2 next-hop-selfneighbor 192.168.1.2 route-map 2-intern outneighbor 192.169.1.7 remote-as 2 nlri unicast multicastneighbor 192.169.1.7 route-map 2-extern outneighbor 192.169.1.7 default-originate!ip classlessip msdp peer 192.168.1.2 connect-source Loopback0ip msdp peer 192.169.1.7ip msdp mesh-group outside-test 192.168.1.2ip msdp originator-id Loopback0!access-list 1 permit 192.168.1.0access-list 1 deny 192.168.1.0 0.0.0.255access-list 1 permit any!route-map 2-extern permit 10match ip address 1!route-map 2-intern deny 10match ip address 1!Command Reference
This section documents the following new commands that configure MSDP. All other commands used in this document can be found in the Cisco IOS 12.0 command reference publications.
Note
In Cisco IOS Release 12.0(1)T or later, you can search and filter the output for show and more commands. This functionality is useful when you need to sort through large amounts of output, or if you want to exclude output that you do not need to see.
To use this functionality, enter a show or more command followed by the "pipe" character (|), one of the keywords begin, include, or exclude, and an expression that you want to search or filter on:
command | {begin | include | exclude} regular-expression
Following is an example of the show atm vc command in which you want the command output to begin with the first line where the expression "PeakRate" appears:
show atm vc | begin PeakRate
For more information on the search and filter functionality, refer to the Cisco IOS Release 12.0(1)T feature module titled CLI String Search.
clear ip msdp peer
To clear the TCP connection to the specified MSDP peer, use the clear ip msdp peer EXEC command.
clear ip msdp peer {ip-address | name}
Syntax Description
Command Modes
EXEC
Command History
Usage Guidelines
This command closes the TCP connection to the peer, resets all the MSDP peer statistics, and clears the input and output queues to and from the MSDP peer.
Examples
The following example clears the TCP connection to the MSDP peer at 120.15.9.8:
clear ip msdp peer 120.15.9.8Related Commands
clear ip msdp sa-cache
To clear MSDP Source-Active cache entries, use the clear ip msdp sa-cache EXEC command.
clear ip msdp sa-cache [group-address | name]
Syntax Description
group-address | name
(Optional) Multicast group address or name for which Source-Active entries are cleared from the Source-Active cache.
Command Modes
EXEC
Command History
Usage Guidelines
In order to have any SA entries in the cache to clear, Source-Active caching must have been enabled with the ip msdp cache-sa-state command
If no multicast group is identified by group address or name, all SA cache entries are cleared.
Examples
The following example clears the Source-Active entries for the multicast group 224.5.6.7 from the cache:
clear ip msdp sa-cache 224.5.6.7Related Commands
Configures the router to create Source-Active state.
Displays (S,G) state learned by MSDP peers.
clear ip msdp statistics
To clear statistics counters for one or all of the MSDP peers without resetting the sessions, use the clear ip msdp statistics EXEC command.
clear ip msdp statistics [peer-address | name]
Syntax Description
peer-address | name
(Optional) Address or name of the MSDP peers whose statistics counters, reset count, and input/output count are cleared.
Command Modes
EXEC
Command History
Examples
The following example clears the counters for the peer named sanjose:
clear ip msdp statistics sanjoseip msdp border
To configure a router that borders a PIM sparse-mode region and dense-mode region to use MSDP, use the ip msdp border global configuration command. To prevent this action, use the no form of this command.
ip msdp border sa-address type number
no ip msdp border sa-address type number
Syntax Description
Defaults
The active sources in the dense-mode region will not participate in MSDP.
Command Modes
Global configuration
Command History
Usage Guidelines
Note
Use this command if you want the router to send Source-Active messages for sources active in the PIM dense-mode region to MSDP peers.
Note
Note that the ip msdp originator-id command also identifies an interface type and number to be used as the RP address. If both the ip msdp border and the ip msdp originator-id command are configured, the latter command prevails. That is, the address derived from the ip msdp originator-id command determines the address of the RP.
Examples
In the following example, the local router is not an RP. It borders a PIM sparse-mode region with a dense-mode region. It uses the IP address of Ethernet interface 0 as the "RP" address in SA messages.
ip msdp border sa-address ethernet0Related Commands
ip msdp cache-sa-state
To have the router create Source-Active (SA) state, use the ip msdp cache-sa-state global configuration command. To prevent this action, use the no form of this command.
ip msdp cache-sa-state [list access-list-number]
no ip msdp cache-sa-state
Syntax Description
list access-list-number
(Optional) Extended IP access list number in the range from 100 to 199 that defines which source/group pairs to cache.
Default
The router does not create SA state.
Command Modes
Global configuration
Command History
Usage Guidelines
Use this command if you prefer to sacrifice some memory in order to overcome the latency problem for a member who joins a group right after the Source-Active message arrives, and misses the message. If you configure this command, the router can supply Source-Active information to the late joiner from cache, instead of making the member wait until the next Source-Active message is received.
This command is not required in every MSDP speaker.
An alternative to this command is using the ip msdp sa-request command to have the router send Source-Active Request messages to the MSDP peer when a new joiner from the group becomes active.
Examples
The following example caches state for all sources in 171.69.0.0/16 sending to groups 224.2.0.0/16:
ip msdp cache-sa-state 100access-list 100 permit ip 171.69.0.0 0.0.255.255 224.2.0.0 0.0.255.255Related Commands
ip msdp default-peer
To define a default peer from which to accept all MSDP Source-Active messages, use the ip msdp default-peer global configuration command. To remove the default peer, use the no form of this command.
ip msdp default-peer ip-address | name [prefix-list list]
no ip msdp default-peer
Syntax Description
Default
No default MSDP peer exists.
Command Modes
Global configuration
Command History
Usage Guidelines
Use the ip msdp default-peer command if you do not want to configure your MSDP peer to be a BGP peer also.
If only one MSDP peer is configured (with the ip msdp peer command), that will be used as a default peer, no matter what. Therefore, you don't need to configure a default peer with this command.
If the prefix-list list keyword and argument are not specified, all SA messages received from the configured default peer are accepted.
Remember to configure a BGP prefix list if you intend to configure the prefix-list list keyword and argument with the ip msdp default-peer command.
If the prefix-list list keyword and argument are specified, SA messages originated from RPs covered by the prefix-list list keyword and argument will be accepted from the configured default peer. If the prefix-list list keyword and argument are specified but no prefix list is configured, the default peer will be used for all prefixes.
You can enter multiple ip msdp default-peer commands, with or without the prefix-list keyword . However, all commands must either have the keyword or all must not have the keyword.
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Examples
The following example configures the router named router.cisco.com as the default peer to the local router:
ip msdp peer 131.12.2.3ip msdp peer 131.13.4.5ip msdp default-peer router.cisco.com !At a stub siteThe following example configures two default peers:
ip msdp peer 131.12.2.3ip msdp peer 131.13.4.5ip msdp default-peer 131.12.2.3 prefix-list site-cip prefix-list site-a permit 131.12.0.0/16ip msdp default-peer 131.13.4.5 prefix-list site-aip prefix-list site-a permit 131.13.0.0/16Related Commands
Configures an MSDP peer.
ip prefix-list
Creates and configures an entry to a prefix list for use in route filtering using prefixes.
ip msdp description
To add descriptive text to the configuration for an MSDP peer, use the ip msdp description global configuration command. To remove the description, use the no form of this command.
ip msdp description {peer-name | peer-address} text
no ip msdp description {peer-name | peer-address}
Syntax Description
peer-name | peer-address
Peer name or address to which this description applies.
text
Description of the MSDP peer.
Default
No description is associated with an MSDP peer.
Command Modes
Global configuration
Command History
Usage Guidelines
Configure a description to make the MSDP peer easier to identify. This description is visible in the output of the show ip msdp peer command.
Examples
The following example configures the router at the IP address 131.107.5.4 with a description indicating it is a router at customer A:
ip msdp description 131.107.5.4 router at customer aip msdp filter-sa-request
To configure the router to send Source-Active Request (SA Request) messages to the MSDP peer when a new joiner from a group becomes active, use the ip msdp filter-sa-request global configuration command. To prevent this action, use the no form of this command.
ip msdp filter-sa-request {ip-address | name} [list access-list-number]
no ip msdp filter-sa-request {ip-address | name}
Syntax Description
Default
If this command is not configured, all Source-Active Request messages are honored. If this command is configured but no access list is specified, all SA Request messages are ignored.
Command Modes
Global configuration
Command History
Usage Guidelines
By default, the router honors all Source-Active Request messages from peers. Use this command if you want to control exactly which SA Request messages the router will honor.
If no access list is specified, all SA Request messages are ignored. If an access list is specified, only SA Request messages from those groups permitted will be honored, and all others will be ignored.
Examples
The following example configures the router to filter Source-Active Request messages from the MSDP peer at 171.69.2.2. Source-Active Request messages from sources on the network 192.4.22.0 pass access list 1 and will be honored; all others will be ignored.
ip msdp filter sa-request 171.69.2.2 list 1access-list 1 permit 192.4.22.0 0.0.0.255Related Commands
ip msdp mesh-group
To configure an MSDP peer to be a member of a mesh group, use the ip msdp mesh-group global configuration command. To remove an MSDP peer from a mesh group, use the no form of this command.
ip msdp mesh-group name {ip-address | name}
no ip msdp mesh-group name {ip-address | name}
Syntax Description
name
Name of the mesh group.
ip-address | name
IP address or name of the MSDP peer to be a member of the mesh group.
Default
The MSDP peers do not belong to a mesh group.
Command Modes
Global configuration
Command History
Usage Guidelines
A mesh group is a group of MSDP speakers that have fully meshed MSDP connectivity among themselves. Any SA messages received from a peer in a mesh group are not forwarded to other peers in the same mesh group.
Mesh groups can be used to achieve two goals:
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Examples
The following example configures the MSDP peer at address 1.1.1.1 to be a member of the mesh group named internal:
ip msdp mesh-group internal 1.1.1.1ip msdp originator-id
To allow an MSDP speaker that originates a Source-Active message to use its interface's IP address as the RP address in the SA message, use the ip msdp originator-id global configuration command. To prevent the RP address from being derived in this way, use the no form of this command.
ip msdp originator-id type number
no ip msdp originator-id type number
Syntax Description
type number
Interface type and number on the local router, whose IP address is used as the RP address in Source-Active messages.
Default
The RP address is used as the Originator ID.
Command Modes
Global configuration
Command History
Usage Guidelines
The ip msdp originator-id command identifies an interface type and number to be used as the RP address in a Source-Active message.
Use this command if you want to configure a logical RP. Because only RPs and MSDP border routers originate SAs, there are times when it is necessary to change the ID used for this purpose.
If both the ip msdp border sa-address and the ip msdp originator-id command are configured, the latter command prevails. That is, the address derived from the ip msdp originator-id command determines the address of the RP to be used in the SA message.
Examples
The following example configures the IP address of Ethernet interface 1 as the RP address in SA messages:
ip msdp originator-id ethernet1Related Commands
Configures a router that borders a PIM sparse-mode region and dense-mode region to use MSDP.
ip msdp peer
To configure an MSDP peer, use the ip msdp peer global configuration command. To remove the peer relationship, use the no form of this command.
ip msdp peer {peer-name | peer-address} [connect-source type number] [remote-as
as-number]no ip msdp peer {peer-name | peer-address}
Syntax Description
Default
No MSDP peer is configured.
Command Modes
Global configuration
Command History
Usage Guidelines
The router specified should also be configured as a BGP neighbor.
If you are also BGP peering with this MSDP peer, you should use the same IP address for MSDP as you do for BGP. However, you are not required to run BGP or MBGP with the MSDP peer, as long as there is a BGP or MBGP path between the MSDP peers. If there is not, you must configure the ip msdp default-peer command.
Examples
The following example configures the router at the IP address 131.108.1.2 as an MSDP peer to the local router. The neighbor belongs to autonomous system 109.
ip msdp peer 131.108.1.2 connect-source ethernet 0router bgp 110network 131.108.0.0neighbor 131.108.1.2 remote-as 109neighbor 131.108.1.2 update-source ethernet 0The following example configures the router named router.cisco.com as an MSDP peer to the local router:
ip msdp peer router.cisco.comThe following example configures that the router named router.cisco.com is an MSDP peer in AS 109. The primary address of Ethernet interface 0 is used as the source address for the TCP connection.
ip msdp peer router.cisco.com connect-source ethernet0 remote-as 109Related Commands
ip msdp redistribute
To configure which (S,G) entries from the multicast routing table are advertised in SA messages originated to MSDP peers, use the ip msdp redistribute global configuration command. To remove the filter, use the no form of this command.
ip msdp redistribute [list access-list-name] [asn aspath-access-list-number] [route-map map]
no ip msdp redistribute
Syntax Description
Defaults
•
•
•
Command Modes
Global configuration
Command History
Usage Guidelines
This command affects SA message origination, not SA message forwarding. If you want to filter which SA messages are forwarded to MSDP peers, use the ip msdp sa-filter in or ip msdp sa-filter out command.
The ip msdp redistribute command controls which (S,G) pairs the router advertises from the multicast routing table. By default, only sources within the local domain are advertised.
For the ip msdp redistribute command:
•
•
•
•
•
Examples
The following example configures which (S,G) entries from the multicast routing table are advertised in SA messages originated to MSDP peers:
ip msdp redistribute route-map customer-sourcesroute-map customer-sources permitmatch as-path customer-asip as-path access-list ^109$Related Commands
ip as-path
Configures BGP path filtering.
Configures a router that borders a PIM sparse-mode region and dense-mode region to use MSDP
ip msdp sa-filter in
To configure an incoming filter list for Source-Active messages received from the specified MSDP peer, use the ip msdp sa-filter in global configuration command. To remove the filter, use the no form of this command.
ip msdp sa-filter in {ip-address | name} [list access-list-name] [route-map map-tag]
no ip msdp sa-filter in {ip-address | name} [list access-list-name] [route-map map-tag]
Syntax Description
Default
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•
Command Modes
Global configuration
Command History
Examples
The following example configures that all Source-Active messages from the peer named router.cisco.com are filtered:
ip msdp peer router.cisco.com connect-source ethernet 0ip msdp sa-filter in router.cisco.comRelated Commands
Configures an MSDP peer.
Configures an outgoing filter list for Source-Active messages sent to the specified MSDP peer
ip msdp sa-filter out
To configure an outgoing filter list for Source-Active messages sent to the specified MSDP peer, use the ip msdp sa-filter out global configuration command. To remove the filter, use the no form of this command.
ip msdp sa-filter out {ip-address | name} [list access-list-name] [route-map map-tag]
no ip msdp sa-filter out {ip-address | name} [list access-list-name] [route-map map-tag]
Syntax Description
Default
•
•
Command Modes
Global configuration
Command History
Examples
The following example allows only (S,G) pairs that pass access list 100 to be forwarded in a Source-Active message to the peer named router.cisco.com:
ip msdp peer router.cisco.com connect-source ethernet 0ip msdp sa-filter out router.cisco.com list 100access-list 100 permit ip 171.69.0.0 0.0.255.255 224.2.0.0 0.0.255.255Related Commands
Configures an MSDP peer.
Configures an incoming filter list for Source-Active messages received from the specified MSDP peer
ip msdp sa-request
To configure the router to send Source-Active Request messages to the MSDP peer when a new joiner from the group becomes active, use the ip msdp sa-request global configuration command. To prevent this action, use the no form of this command.
ip msdp sa-request {ip-address | name}
no ip msdp sa-request {ip-address | name}
Syntax Description
ip-address | name
IP address or name of the MSDP peer from which the local router requests Source-Active messages when a new joiner for the group becomes active.
Default
The router does not send Source-Active Request messages to the MSDP peer.
Command Modes
Global configuration
Command History
Usage Guidelines
By default, the router does not send any Source-Active Request messages to its MSDP peers when a new member joins a group and wants to receive multicast traffic. The new member just waits to receive any Source-Active messages that eventually arrive.
Use this command if you want a new member of a group to learn the current, active multicast sources in a connected PIM sparse-mode domain that are sending to a group. The router will send Source-Active Request messages to the specified MSDP peer when a new member joins a group. The peer replies with the information it is SA cache. If the peer does not have a cache configured, this command provides nothing.
An alternative to this command is using the ip msdp cache-sa-state command to have the router cache messages.
Examples
The following example configures the router to send Source-Active Request messages to the MSDP peer at 171.69.1.1:
ip msdp sa-request 171.69.1.1Related Commands
Configures the router to create Source-Active (SA) state.
Configures an MSDP peer.
ip msdp shutdown
To administratively shut down a configured MSDP peer, use the ip msdp shutdown global configuration command. To bring the peer back up, use the no form of this command.
ip msdp shutdown {peer-address | peer-name}
no ip msdp shutdown {peer-address | peer-name}
Syntax Description
Default
No action is taken to shut down an MSDP peer.
Command Modes
Global configuration
Command History
Examples
The following example shuts down the MSDP peer at IP address 136.5.7.20:
ip msdp shutdown 136.5.7.20Related Commands
ip msdp ttl-threshold
To limit which multicast data packets are sent in SA messages to an MSDP peer, use the ip msdp ttl-threshold global configuration command. To restore the default value, use the no form of this command.
ip msdp ttl-threshold {ip-address | name} ttl
no ip msdp ttl-threshold {ip-address | name}
Syntax Description
Default
ttl = 0
Command Modes
Global configuration
Command History
Usage Guidelines
This command limits which multicast data packets are sent in data-encapsulated SA messages. Only multicast packets with an IP-header TTL greater than or equal to the ttl argument are sent to the MSDP peer specified by the IP address or name.
Use this command if you want to use TTL to scope your multicast data traffic. For example, you could limit internal traffic to a TTL of 8. If you want other groups to go to external locations, you would need to send those packets with a TTL greater than 8.
Examples
The following example configures a TTL threshold of 8 hops:
ip msdp ttl-threshold 8Related Commands
show ip msdp count
To display the number of sources and groups originated in MSDP Source-Active messages, use the show ip msdp count EXEC command.
show ip msdp count [autonomous-system-number]
Syntax Description
autonomous-system-number
(Optional) Displays the number of sources and group originated in SA messages from the specified autonomous system.
Command Modes
EXEC
Command History
Usage Guidelines
The ip msdp cache-sa-state command must be configured for this command to have any output.
Examples
The following is sample output of the show ip msdp count command:
Router# show ip msdp countSA State per ASN Counters, <asn>: <# sources>/<# groups>Total entries: 2398267: 1/1, 704: 1479/143, 3582: 236/28, 6461: 50/010876: 5/1, 10888: 627/88describes the fields in the display.
Table 1 show ip msdp count Field Descriptions
Total entries
Total number of SA entries in the SA cache.
267: 1/1
Autonomous system 267: 1 source / 1group
Related Commands
show ip msdp peer
To display detailed information about the MSDP peer, use the show ip msdp peer EXEC command.
show ip msdp peer peer-address | name
Syntax Description
Command Modes
EXEC
Command History
Examples
The following is sample output of the show ip msdp peer command:
Router# show ip msdp peer 198.9.200.65MSDP Peer Status SummaryPeer Address AS State Uptime/ Msgs Sent/ Peer NameDowntime Received198.9.200.65 10888 Up 2d10h 50584/48022 ?TCP connection source: Loopback 0SA input filter: NoneSA output filter: NoneSA-Request filter: NoneSending SA-Requests to peer: Disableddescribes the fields in the display.
Related Commands
show ip msdp sa-cache
To display (S,G) state learned from MSDP peers, use the show ip msdp sa-cache EXEC command.
show ip msdp sa-cache [group-address | source-address | group-name | source-name]
[group-address | source-address | group-name | source-name] [autonomous-system-number]Syntax Description
Command Modes
EXEC
Command History
Usage Guidelines
State is cached only if the ip msdp cache-sa-state command is configured.
Examples
The following is sample output of the show ip msdp sa-cache command:
Router# show ip msdp sa-cacheMSDP Source-Active Cache - 2398 entries(137.39.41.33, 238.105.148.0), RP 137.39.3.111, MBGP/AS 704, 2d10h/00:05:33(130.240.112.8, 224.2.0.1), RP 198.9.200.65, MBGP/AS 10888, 00:03:21/00:02:38(171.69.10.13, 227.37.32.1), RP 137.39.3.92, MBGP/AS 704, 05:22:20/00:03:32(134.67.66.18, 233.0.0.1), RP 137.39.3.111, MBGP/AS 704, 2d10h/00:05:35(134.67.66.148, 233.0.0.1), RP 137.39.3.111, MBGP/AS 704, 2d10h/00:05:35(171.69.10.13, 227.37.32.2), RP 137.39.3.92, MBGP/AS 704, 00:44:30/00:01:31(128.223.70.203, 224.2.236.2), RP 128.223.253.7, MBGP/AS 3582, 02:34:16/00:05:49(206.190.42.104, 236.195.56.2), RP 137.39.3.92, MBGP/AS 704, 04:21:13/00:05:22(171.69.10.13, 227.37.32.3), RP 137.39.3.92, MBGP/AS 704, 00:44:30/00:02:31(161.44.15.43, 224.0.92.3), RP 198.9.200.65, MBGP/AS 10888, 6d09h/00:05:35(161.44.15.111, 224.0.92.3), RP 198.9.200.65, MBGP/AS 10888, 16:18:08/00:05:35(161.44.21.45, 224.0.92.3), RP 198.9.200.65, MBGP/AS 10888, 16:18:08/00:05:35(161.44.15.75, 224.0.92.3), RP 198.9.200.65, MBGP/AS 10888, 08:40:52/00:05:35(161.44.15.100, 224.0.92.3), RP 198.9.200.65, MBGP/AS 10888, 08:40:52/00:05:35(171.69.10.13, 227.37.32.6), RP 137.39.3.92, MBGP/AS 704, 00:45:30/00:05:31(137.39.41.33, 224.247.228.10), RP 137.39.3.111, MBGP/AS 704, 2d10h/00:05:35(128.146.222.210, 224.2.224.13), RP 137.39.3.92, MBGP/AS 704, 01:51:53/00:05:22(137.39.41.33, 229.231.124.13), RP 137.39.3.111, MBGP/AS 704, 2d10h/00:05:33(128.223.32.138, 224.2.200.23), RP 128.223.253.7, MBGP/AS 3582, 21:33:40/00:05:49(128.223.75.244, 224.2.200.23), RP 128.223.253.7, MBGP/AS 3582, 21:33:40/00:05:49describes the significant fields in the display.
Related Commands
Clears MSDP Source-Active cache entries.
Configures the router to create Source-Active (SA) state.
show ip msdp summary
To display MSDP peer status, use the show ip msdp summary EXEC command.
show ip msdp summary
Syntax Description
This command has no arguments or keywords.
Command Modes
EXEC
Command History
Examples
The following is sample output of the show ip msdp summary command:
Router# show ip msdp summaryMSDP Peer Status SummaryPeer Address AS State Uptime/ Msgs Sent/ Peer NameDowntime Received198.9.200.65 10888 Up 2d10h 50569/48007 ?198.9.201.122 6461 Up 3d13h 145892/11218?198.9.200.34 704 Up 06:34:44 6118/6508 ?198.9.201.113 3967 Listen 4d11h 0/0 ?198.9.201.2 24 Up 02:27:03 4880/160 ?describes the significant fields in the display.
Debug Commands
This section describes the following new debug commands:
debug ip msdp
To debug MSDP activity, use the debug ip msdp EXEC command.
[no] debug ip msdp [peer-address | name] [detail] [routes]
Syntax Description
peer-address | name
(Optional) Logs debug events for that peer only.
detail
(Optional) Provides more detailed debugging information.
routes
(Optional) Displays the contents of Source-Active messages.
Command History
Examples
The following is sample output of the debug ip msdp command:
Router# debug ip msdpMSDP debugging is onRouter#MSDP: 192.150.44.254: Received 1388-byte message from peerMSDP: 192.150.44.254: SA TLV, len: 1388, ec: 115, RP: 137.39.3.92MSDP: 192.150.44.254: Peer RPF check passed for 137.39.3.92, used EMBGP peerMSDP: 192.150.44.250: Forward 1388-byte SA to peerMSDP: 192.150.44.254: Received 1028-byte message from peerMSDP: 192.150.44.254: SA TLV, len: 1028, ec: 85, RP: 137.39.3.92MSDP: 192.150.44.254: Peer RPF check passed for 137.39.3.92, used EMBGP peerMSDP: 192.150.44.250: Forward 1028-byte SA to peerMSDP: 192.150.44.254: Received 1388-byte message from peerMSDP: 192.150.44.254: SA TLV, len: 1388, ec: 115, RP: 137.39.3.111MSDP: 192.150.44.254: Peer RPF check passed for 137.39.3.111, used EMBGP peerMSDP: 192.150.44.250: Forward 1388-byte SA to peerMSDP: 192.150.44.250: Received 56-byte message from peerMSDP: 192.150.44.250: SA TLV, len: 56, ec: 4, RP: 205.167.76.241MSDP: 192.150.44.250: Peer RPF check passed for 205.167.76.241, used EMBGP peerMSDP: 192.150.44.254: Forward 56-byte SA to peerMSDP: 192.150.44.254: Received 116-byte message from peerMSDP: 192.150.44.254: SA TLV, len: 116, ec: 9, RP: 137.39.3.111MSDP: 192.150.44.254: Peer RPF check passed for 137.39.3.111, used EMBGP peerMSDP: 192.150.44.250: Forward 116-byte SA to peerMSDP: 192.150.44.254: Received 32-byte message from peerMSDP: 192.150.44.254: SA TLV, len: 32, ec: 2, RP: 137.39.3.78MSDP: 192.150.44.254: Peer RPF check passed for 137.39.3.78, used EMBGP peerMSDP: 192.150.44.250: Forward 32-byte SA to peerdescribes the significant fields in the display.
Table 5 debug ip msdp Field Descriptions
MSDP
Protocol being debugged.
192.150.44.254:
IP address of MSDP peer.
Received 1388-byte message from peer
MSDP event.
debug ip msdp resets
To debug MSDP peer reset reasons, use the debug ip msdp resets EXEC command.
[no] debug ip msdp resets
Syntax Description
This command has no keywords or arguments.
Command Modes
EXEC
Command History
