For more information about the concepts of designated router (DR), bootstrap router (BSR), candidate-BSR (C-BSR), rendezvous point (RP), candidate RP (C-RP), shortest path tree (SPT) and rendezvous point tree (RPT) mentioned in this manual, see the chapter “Configuring PIM.”

MSDP overview

Multicast source discovery protocol (MSDP) is an inter-domain multicast solution developed to address the interconnection of protocol independent multicast sparse mode (PIM-SM) domains. It is used to discover multicast source information in other PIM-SM domains.

In the basic PIM-SM mode, a multicast source registers only with the RP in the local PIM-SM domain, and the multicast source information of a domain is isolated from that of another domain. As a result, the RP is aware of the source information only within the local domain and a multicast distribution tree is built only within the local domain to deliver multicast data from a local multicast source to local receivers. If there is a mechanism that allows RPs of different PIM-SM domains to share their multicast source information, the local RP will be able to join multicast sources in other domains and multicast data can be transmitted among different domains.

MSDP achieves this goal. With MSDP peer relationships established between appropriate routers in the network, the RPs of different PIM-SM domains are interconnected with one another. Source active (SA) messages are exchanged between these MSDP peers and thus the multicast source information is shared among these different domains.

CAUTION:

· MSDP is applicable only if the intra-domain multicast protocol is PIM-SM.

· MSDP is meaningful only for the any-source multicast (ASM) model.

How MSDP works

MSDP peers

With one or more pairs of MSDP peers configured in the network, an MSDP interconnection map is formed, where the RPs of different PIM-SM domains are interconnected in series. Relayed by these MSDP peers, an SA message sent by an RP can be delivered to all other RPs.

Figure 1 Where MSDP peers are in the network

As shown in Figure 1, an MSDP peer can be created on any PIM-SM router. MSDP peers created on PIM-SM routers that assume different roles function differently.

1. MSDP peers on RPs include the following types:

¡ Source-side MSDP peer—The MSDP peer nearest to the multicast source (Source), typically the source-side RP, like RP 1. The source-side RP creates SA messages and sends the messages to its remote MSDP peer to notify the MSDP peer of the locally registered multicast source information. A source-side MSDP peer must be created on the source-side RP. Otherwise, it cannot advertise the multicast source information out of the PIM-SM domain.

¡ Receiver-side MSDP peer—The MSDP peer nearest to the receivers, typically the receiver-side RP, like RP 3. After receiving an SA message, the receiver-side MSDP peer resolves the multicast source information carried in the message and joins the SPT rooted at the source across the PIM-SM domain. When multicast data from the multicast source arrives, the receiver-side MSDP peer forwards the data to the receivers along the RPT.

¡ Intermediate MSDP peer—An MSDP peer with multicast remote MSDP peers, like RP 2. An intermediate MSDP peer forwards SA messages received from one remote MSDP peer to other remote MSDP peers, functioning as a relay of multicast source information.

2. MSDP peers created on common PIM-SM routers (other than RPs)

Router A and Router B are MSDP peers on common multicast routers. Such MSDP peers just forward received SA messages.

NOTE:

In a PIM-SM network running the BSR mechanism, the RP is dynamically elected from C-RPs. To enhance network robustness, a PIM-SM network typically has more than one C-RP. As the RP election result is unpredictable, MSDP peering relationships should be built among all C-RPs so that the winner C-RP is always on the “MSDP interconnection map”, while loser C-RPs will assume the role of common PIM-SM routers on the “MSDP interconnection map”.

Inter-domain multicast delivery through MSDP

As shown in Figure 2, an active source (Source) exists in the domain PIM-SM 1, and RP 1 has learned the existence of Source through multicast source registration. If RPs in PIM-SM 2 and PIM-SM 3 also wish to know the specific location of Source so that receiver hosts can receive multicast traffic originated from it, MSDP peering relationships should be established between RP 1 and RP 3 and between RP 3 and RP 2 respectively.

Figure 2 Inter-domain multicast delivery through MSDP

The process of implementing PIM-SM inter-domain multicast delivery by leveraging MSDP peers is as follows:

1. When the multicast source in PIM-SM 1 sends the first multicast packet to multicast group G, DR 1 encapsulates the multicast data within a register message and sends the register message to RP 1. Then, RP 1 gets aware of the information related to the multicast source.

2. As the source-side RP, RP 1 creates SA messages and periodically sends the SA messages to its MSDP peer. An SA message contains the source address (S), the multicast group address (G), and the address of the RP which has created this SA message (namely RP 1).

3. On MSDP peers, each SA message is subject to a reverse path forwarding (RPF) check and multicast policy–based filtering, so that only SA messages that have arrived along the correct path and passed the filtering are received and forwarded. This avoids delivery loops of SA messages. In addition, you can configure MSDP peers into an MSDP mesh group so as to avoid flooding of SA messages between MSDP peers.

4. SA messages are forwarded from one MSDP peer to another, and finally the information of the multicast source traverses all PIM-SM domains with MSDP peers (PIM-SM 2 and PIM-SM 3 in this example).

5. Upon receiving the SA message create by RP 1, RP 2 in PIM-SM 2 checks whether there are any receivers for the multicast group in the domain.

¡ If so, the RPT for the multicast group G is maintained between RP 2 and the receivers. RP 2 creates an (S, G) entry, and sends an (S, G) join message hop by hop towards DR 1 at the multicast source side, so that it can directly join the SPT rooted at the source over other PIM-SM domains. Then, the multicast data can flow along the SPT to RP 2 and is forwarded by RP 2 to the receivers along the RPT. Upon receiving the multicast traffic, the DR at the receiver side (DR 2) decides whether to initiate an RPT-to-SPT switchover process.

¡ If no receivers for the group exist in the domain, RP 2 does dot create an (S, G) entry and does join the SPT rooted at the source.

NOTE:

· An MSDP mesh group refers to a group of MSDP peers that have MSDP peering relationships among one another and share the same group name.

· When using MSDP for inter-domain multicasting, once an RP receives information form a multicast source, it no longer relies on RPs in other PIM-SM domains. The receivers can override the RPs in other domains and directly join the multicast source based SPT.

RPF check rules for SA messages

As shown in Figure 3, there are five autonomous systems in the network, AS 1 through AS 5, with IGP enabled on routers within each AS and BGP or MBGP as the interoperation protocol among different ASs. Each AS contains at least one PIM-SM domain and each PIM-SM domain contains one ore more RPs. MSDP peering relationships have been established among different RPs. RP 3, RP 4 and RP 5 are in an MSDP mesh group. On RP 7, RP 6 is configured as its static RPF peer.

NOTE:

After an RP receives an SA message from a static RPF peer, the RP accepts the SA message and forwards it to other peers without performing an RPF check.

Figure 3 Diagram for RPF check for SA messages

As illustrated in Figure 3, these MSDP peers dispose of SA messages according to the following RPF check rules:

1. When RP 2 receives an SA message from RP 1, because the source-side RP address carried in the SA message is the same as the MSDP peer address, which means that the MSDP peer where the SA is from is the RP that has created the SA message, RP 2 accepts the SA message and forwards it to its other MSDP peer (RP 3).

2. When RP 3 receives the SA message from RP 2, because the SA message is from an MSDP peer (RP 2) in the same AS, and the MSDP peer is the next hop on the optimal path to the source-side RP, RP 3 accepts the message and forwards it to other peers (RP 4 and RP 5).

3. When RP 4 and RP 5 receive the SA message from RP 3, because the SA message is from an MSDP peer (RP 3) in the same mesh group, RP 4 and RP 5 both accept the SA message, but they do not forward the message to other members in the mesh group; instead, they forward it to other MSDP peers (RP 6 in this example) out of the mesh group.

4. When RP 6 receives the SA messages from RP 4 and RP 5 (suppose RP 5 has a higher IP address), although RP 4 and RP 5 are in the same AS (AS 3) and both are MSDP peers of RP 6, RP 6 accepts only the SA message from the MSDP with a higher IP address, that is, RP 5.

5. When RP 7 receives the SA message from RP 6, because the SA message is from a static RPF peer (RP 6), RP 7 accepts the SA message and forwards it to other peer (RP 8).

6. When RP 8 receives the SA message from RP 7, a BGP or MBGP route exists between two MSDP peers in different ASs. Because the SA message is from an MSDP peer (RP 7) in a different AS, and the MSDP peer is the next hop on the BGP or MBGP route to the source-side RP, RP 8 accepts the message and forwards it to its other peer (RP 9).

7. When RP 9 receives the SA message from RP 8, because RP 9 has only one MSDP peer, RP 9 accepts the SA message.

SA messages from other paths than described above will not be accepted nor forwarded by MSDP peers.

Intra-domain Anycast RP through MSDP

Anycast RP refers to such an application that enables load balancing and redundancy backup between two or more RPs within a PIM-SM domain by configuring the same IP address for, and establishing MSDP peering relationships between, these RPs.

As shown in Figure 4, within a PIM-SM domain, a multicast source sends multicast data to multicast group G, and Receiver is a member of the multicast group. To implement Anycast RP, configure the same IP address (known as Anycast RP address, typically a private address) on Router A and Router B, configure these interfaces as C-RPs, and establish an MSDP peering relationship between Router A and Router B.

NOTE:

Usually an Anycast RP address is configured on a logic interface, like a loopback interface.

Figure 4 Intra-domain Anycast RP through MSDP

The work process of Anycast RP is as follows:

1. The multicast source registers with the nearest RP. In this example, Source registers with RP 1, with its multicast data encapsulated in the register message. When the register message arrives to RP 1, RP 1 de-encapsulates the message.

2. Receivers send join messages to the nearest RP to join in the RPT rooted as this RP. In this example, Receiver joins the RPT rooted at RP 2.

3. RPs share the registered multicast information by means of SA messages. In this example, RP 1 creates an SA message and sends it to RP 2, with the multicast data from Source encapsulated in the SA message. When the SA message reaches RP 2, RP 2 de-encapsulates the message.

4. Receivers receive the multicast data along the RPT and directly join the SPT rooted at the multicast source. In this example, RP 2 forwards the multicast data down the RPT. When Receiver receives the multicast data from Source, it directly joins the SPT rooted at Source.

The significance of Anycast RP is as follows:

· Optimal RP path: A multicast source registers with the nearest RP so that an SPT with the optimal path is built; a receiver joins the nearest RP so that an RPT with the optimal path is built.

· Load balancing between RPs: Each RP just needs to maintain part of the source/group information within the PIM-SM domain and forward part of the multicast data, thus achieving load balancing between different RPs.

· Redundancy backup between RPs: When an RP fails, the multicast source previously registered on it or the receivers previous joined it will register with or join another nearest RP, thus achieving redundancy backup between RPs.

CAUTION:

· Be sure to configure a 32-bit subnet mask (255.255.255.255) for the Anycast RP address, namely configure the Anycast RP address into a host address.

· An MSDP peer address must be different from the Anycast RP address.

Multi-instance MSDP

MSDP peering relationship can be built between multicast-enabled interfaces that belong to the same instance. Through exchanges of SA messages between MSDP peers, the MSDP mechanism makes VPN multicast transmission between different PIM-SM domains possible.

A multicast router running multiple MSDP instances maintains an independent set of MSDP mechanism for each instance it supports, including SA cache, peering connection, timers, sending cache, and cache for exchanging information with PIM, while one instance is isolated from another; therefore, interoperability between MSDP and PIM-SM is available only within the same instance.

Protocols and standards

· RFC 3618: Multicast Source Discovery Protocol (MSDP)

· RFC 3446: Anycast Rendezvous Point (RP) mechanism using Protocol Independent Multicast (PIM) and Multicast Source Discovery Protocol (MSDP)

MSDP configuration task list

Complete these tasks to configure MSDP:

Task		Remarks
Configuring basic functions of MSDP	Enabling MSDP	Required
	Creating an MSDP peer connection	Required
	Configuring a static RPF peer	Optional
Configuring an MSDP peer connection	Configuring MSDP peer description	Optional
	Configuring an MSDP mesh group	Optional
	Configuring MSDP peer connection control	Optional
Configuring SA messages related parameters	Configuring SA message content	Optional
	Configuring SA request messages	Optional
	Configuring an SA message filtering rules	Optional
	Configuring the SA cache mechanism	Optional

Configuring basic functions of MSDP

NOTE:

All the configuration tasks should be carried out on RPs in PIM-SM domains, and each of these RPs acts as an MSDP peer.

Configuration prerequisites

Before configuring the basic functions of MSDP, complete the following tasks:

· Configure any unicast routing protocol so that all devices in the domain are interoperable at the network layer.

· Configure PIM-SM to enable intra-domain multicast forwarding.

· Determine the IP addresses of MSDP peers.

· Determine the address prefix list for an RP address filtering policy.

Enabling MSDP

Enabling MSDP globally on the public network

To enable MSDP globally on the public network:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enable IP multicast routing.	multicast routing-enable	Disabled by default.
3. Enable MSDP and enter public network MSDP view.	msdp [ vpn-instance vpn-instance-name ]	Disabled by default.

Enabling MSDP in a VPN instance

Step	Command	Description
1. Enter system view.	system-view	N/A
2. Create a VPN instance and enter VPN instance view.	ip vpn-instance vpn-instance-name	N/A
3. Configure a route-distinguisher (RD) for the VPN instance.	route-distinguisher route-distinguisher	No RD is configured by default.
4. Enable IP multicast routing.	multicast routing-enable	Disabled by default.
5. Return to system view.	quit	N/A
6. Enable MSDP and enter VPN instance MSDP view.	msdp [ vpn-instance vpn-instance-name ]	Disabled by default.

NOTE:

· For more information about the ip vpn-instance and route-distinguisher commands, see MPLS Command Reference.

· For more information about the multicast routing-enable command, see IP Multicast Command Reference.

Creating an MSDP peer connection

An MSDP peering relationship is identified by an address pair, namely the address of the local MSDP peer and that of the remote MSDP peer. An MSDP peer connection must be created on both devices that are a pair of MSDP peers.

To create an MSDP peer connection:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter public network MSDP view or VPN instance MSDP view.	msdp [ vpn-instance vpn-instance-name ]	N/A
3. Create an MSDP peer connection.	peer peer-address connect-interface interface-type interface-number	No MSDP peer connection is created by default.

NOTE:

If an interface of the router is shared by an MSDP peer and a BGP or MBGP peer at the same time, we recommend that you configuration the same IP address for the MSDP peer and BGP or MBGP peer.

Configuring a static RPF peer

Configuring static RPF peers avoids RPF check of SA messages.

To configure a static RPF peer:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter public network MSDP view or VPN instance MSDP view.	msdp [ vpn-instance vpn-instance-name ]	N/A
3. Configure a static RPF peer.	static-rpf-peer peer-address [ rp-policy ip-prefix-name ]	No static RPF peer is configured by default.

NOTE:

· You can configure a static RPF peer only after an MSDP peer connection is created.

· If only one MSDP peer is configured on a router, this MSDP will be registered as a static RPF peer.

Configuring an MSDP peer connection

Configuration prerequisites

Before configuring MSDP peer connection, complete the following tasks:

· Configure any unicast routing protocol so that all devices in the domain are interoperable at the network layer.

· Configure basic MSDP functions.

· Determine the description information of MSDP peers.

· Determine the name of an MSDP mesh group.

· Determine the MSDP peer connection retry interval.

Configuring MSDP peer description

With the MSDP peer description information, the administrator can easily distinguish different MSDP peers and thus better manage MSDP peers.

To configure description for an MSDP peer:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter public network MSDP view or VPN instance MSDP view.	msdp [ vpn-instance vpn-instance-name ]	N/A
3. Configure description for an MSDP peer.	peer peer-address description text	No description for MSDP peers is configured by default.

Configuring an MSDP mesh group

An AS may contain multiple MSDP peers. You can use the MSDP mesh group mechanism to avoid SA message flooding among these MSDP peers and optimize the multicast traffic.

On one hand, an MSDP peer in an MSDP mesh group forwards SA messages from outside the mesh group that have passed the RPF check to the other members in the mesh group; on the other hand, a mesh group member accepts SA messages from inside the group without performing an RPF check, and does not forward the message within the mesh group either. This mechanism not only avoids SA flooding but also simplifies the RPF check mechanism, because BGP or MBGP is not needed to run between these MSDP peers.

By configuring the same mesh group name for multiple MSDP peers, you can create a mesh group and assign those MSDP peers to that mesh group.

To create an MSDP mesh group:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter public network MSDP view or VPN instance MSDP view.	msdp [ vpn-instance vpn-instance-name ]	N/A
3. Create an MSDP mesh group and assign an MSDP peer to that mesh group.	peer peer-address mesh-group name	An MSDP peer does not belong to any mesh group by default.

NOTE:

· Before grouping multiple routers into an MSDP mesh group, make sure that these routers are interconnected with one another.

· The mesh group name must be the same for all the peers.

· If you configure more than one mesh group name on an MSDP peer, only the last configuration is effective.

Configuring MSDP peer connection control

MSDP peers are interconnected over TCP (port number 639). You can flexibly control sessions between MSDP peers by manually deactivating and reactivating the MSDP peering connections. When the connection between two MSDP peers is deactivated, SA messages will no longer be delivered between them, and the TCP connection is closed without any connection setup retry, but the configuration information will remain unchanged.

When a new MSDP peer is created, or when a previously deactivated MSDP peer connection is reactivated, or when a previously failed MSDP peer attempts to resume operation, a TCP connection is required. You can flexibly adjust the interval between MSDP peering connection retries.

To configure MSDP peer connection control:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter public network MSDP view or VPN instance MSDP view.	msdp [ vpn-instance vpn-instance-name ]	N/A
3. Deactivate an MSDP peer.	shutdown peer-address	Optional Activated by default
4. Configure the interval between MSDP peer connection retries.	timer retry interval	Optional 30 seconds by default

Configuring SA messages related parameters

Configuration prerequisites

Before configuring SA message delivery, complete the following tasks:

· Configure any unicast routing protocol so that all devices in the domain are interoperable at the network layer.

· Configure basic MSDP functions.

· Determine the ACL for filtering SA request messages.

· Determine the ACL for creating SA messages.

· Determine the ACL for filtering SA messages to be received and forwarded.

· Determine the TTL threshold for multicast packets encapsulation in SA messages.

· Determine the maximum number of (S, G) entries learned from the specified MSDP peer that the router can cache.

Configuring SA message content

Some multicast sources send multicast data at an interval longer than the aging time of (S, G) entries. In this case, the source-side DR has to encapsulate multicast data packet by packet in register messages and send them to the source-side RP. The source-side RP transmits the (S, G) information to the remote RP through SA messages. Then the remote RP joins the source-side DR and builds an SPT. Since the (S, G) entries have timed out, remote receivers can never receive the multicast data from the multicast source.

If the source-side RP is enabled to encapsulate register messages in SA messages, when there is a multicast packet to deliver, the source-side RP encapsulates a register message containing the multicast packet in an SA message and sends it out. After receiving the SA message, the remote RP de-encapsulates the SA message and delivers the multicast data contained in the register message to the receivers along the RPT.

The MSDP peers deliver SA messages to one another. Upon receiving an SA message, a router performs RPF check on the message. If the router finds that the remote RP address is the same as the local RP address, it will discard the SA message. In the Anycast RP application, however, you need to configure RPs with the same IP address on two or more routers in the same PIM-SM domain, and configure these routers as MSDP peers to one another. Therefore, a logic RP address (namely, the RP address on the logic interface) that is different from the actual RP address must be designated for SA messages so that the messages can pass the RPF check.

To configure the SA message content:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter public network MSDP view or VPN instance MSDP view.	msdp [ vpn-instance vpn-instance-name ]	N/A
3. Enable encapsulation of a register message.	encap-data-enable	Optional Disabled by default
4. Configure the interface address as the RP address in SA messages.	originating-rp interface-type interface-number	Optional PIM RP address by default

Configuring SA request messages

By default, upon receiving a new Join message, a router does not send an SA request message to any MSDP peer; instead, it waits for the next SA message from its MSDP peer. This will cause the receiver to delay obtaining multicast source information. To enable a new receiver to get the active multicast source information as early as possible, you can configure routers to send SA request messages to the designated MSDP peers upon receiving a Join message of a new receiver.

To configure SA message transmission and filtering:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter public network MSDP view or VPN instance MSDP view.	msdp [ vpn-instance vpn-instance-name ]	N/A
3. Enable the device to send SA request messages.	peer peer-address request-sa-enable	Optional. By default, upon receiving a new Join message, a router does not send an SA request message to any MSDP peer; instead, it waits for the next SA message from its MSDP peer.
4. Configure a filtering rule for SA request messages.	peer peer-address sa-request-policy [ acl acl-number ]	Optional. SA request messages are not filtered by default.

CAUTION:

Before you can enable the device to send SA requests, be sure to disable the SA message cache mechanism.

NOTE:

· With the function of sending SA request messages enabled, upon receiving a Join message from a new multicast receiver, the device sends an SA request message to the remote MSDP peer specified by this command, and the remote peer responds with cached SA information. Upon sending an SA request message, the device receives the responses from all active multicast sources.

· If you do not specify an ACL rule when you configure an SA message filtering rule, all the SA requests from MSDP peers will be ignored. If you specify an ACL, SA request messages that pass the filtering will be accepted, while all other SA request messages will be ignored.

Configuring an SA message filtering rules

By configuring an SA message creation rule, you can enable the router to filter the (S, G) entries to be advertised when creating an SA message, so that the propagation of messages of multicast sources is controlled.

By configuring a filtering rule for receiving or forwarding SA messages, you can enable the router to filter the (S, G) forwarding entries to be advertised when receiving or forwarding an SA message, so that the propagation of multicast source information is controlled at SA message reception or forwarding.

By configuring a TTL threshold for multicast data packet encapsulation in an SA message, you can control the multicast data packet encapsulation in SA messages and limit the propagation range of SA messages:

· Before creating an SA message with an encapsulated multicast data packet, the router checks the TTL value of the multicast data packet. If the TTL value is less than the threshold, the router does not create an SA message. If the TTL value is greater than or equal to the threshold, the router encapsulates the multicast data in an SA message and sends the SA message out.

· Upon receiving an SA message with encapsulated multicast data, the router decrements the TTL value of the multicast packet by 1 and then checks the TTL value. If the TTL value is less than the threshold, the router does not forward the SA message to the designated MSDP peer. If the TTL value is greater than or equal to the threshold, the router re-encapsulates the multicast data in an SA message and sends the SA message out.

To configure a filtering rule for receiving or forwarding SA messages:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter public network MSDP view or VPN instance MSDP view.	msdp [ vpn-instance vpn-instance-name ]	N/A
3. Configure an SA message creation rule.	import-source [ acl acl-number ]	No restrictions on (S, G) entries by default
4. Configure a filtering rule for receiving or forwarding SA messages.	peer peer-address sa-policy { import \| export } [ acl acl-number ]	No filtering rule by default
5. Configure the TTL threshold for multicast data packet encapsulation in SA messages.	peer peer-address minimum-ttl ttl-value	Optional 0 by default

Configuring the SA cache mechanism

To reduce the time spent in obtaining the multicast information, you can enable the SA cache mechanism to cache (S, G) entries contained in SA messages locally on the router. However, the more (S, G) entries are cached, the larger memory space of the router is used.

With the SA cache mechanism enabled, when receiving a new (*, G) join message, the router searches its SA cache first:

· If the corresponding (S, G) entry does not exist in the cache, the router waits for the SA message its MSDP peer will send in the next cycle;

· If the corresponding (S, G) entry exists in the cache, the router joins the corresponding SPT rooted at S.

To protect the router effectively against denial of service (DoS) attacks, you can set a limit on the number of (S, G) entries the router can cache.

To configure the SA message cache:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter public network MSDP view or VPN instance MSDP view.	msdp [ vpn-instance vpn-instance-name ]	N/A
3. Enable the SA message cache mechanism.	cache-sa-enable	Optional Enabled by default
4. Configure the maximum number of (S, G) entries learned from the specified MSDP peer the router can cache.	peer peer-address sa-cache-maximum sa-limit	Optional 8192 by default

Displaying and maintaining MSDP

Task	Command	Remarks
Display brief information of MSDP peers.	display msdp [all-instance \| vpn-instance vpn-instance-name ] brief [ state { connect \| down \| listen \| shutdown \| up } ] [ \| { begin \| exclude \| include } regular-expression ]	Available in any view
Display the status of MSDP peers.	display msdp [all-instance \| vpn-instance vpn-instance-name ] peer-status [ peer-address ] [ \| { begin \| exclude \| include } regular-expression ]	Available in any view
Display the (S, G) entry information in the SA cache.	display msdp [all-instance \| vpn-instance vpn-instance-name ] sa-cache [ group-address \| source-address \| as-number ] * [ \| { begin \| exclude \| include } regular-expression ]	Available in any view
Display the number of (S, G) entries in the SA cache.	display msdp [all-instance \| vpn-instance vpn-instance-name ] sa-count [ as-number ] [ \| { begin \| exclude \| include } regular-expression ]	Available in any view
Reset the TCP connection with an MSDP peer.	reset msdp [all-instance \| vpn-instance vpn-instance-name ] peer [ peer-address ]	Available in user view
Clear (S, G) entries in the SA cache.	reset msdp [all-instance \| vpn-instance vpn-instance-name ] sa-cache [ group-address ]	Available in user view
Clear statistics for an MSDP peer.	reset msdp [all-instance \| vpn-instance vpn-instance-name ] statistics [ peer-address ]	Available in user view

MSDP configuration examples

PIM-SM Inter-domain multicast configuration

Network requirements

The network has two ASs: AS 100 and AS 200. OSPF is running within each AS, and BGP is running between the two ASs.

PIM-SM 1 belongs to AS 100, while PIM-SM 2 and PIM-SM 3 belong to AS 200. Each PIM-SM domain has at least one multicast source or receiver.

Configure Loopback 0 as the C-BSR and C-RP of the related PIM-SM domain on Router B, Router C, and Router E.

Set up MSDP peering relationships between the RPs of the PIM-SM domains to share multicast source information among the PIM-SM domains.

Figure 5 Network diagram

Device	Interface	IP address	Device	Interface	IP address
Router A	GE3/1/1	10.110.1.2/24	Router D	GE3/1/1	10.110.4.2/24
	GE3/1/2	10.110.2.1/24		GE3/1/2	10.110.5.1/24
	GE3/1/3	10.110.3.1/24	Router E	GE3/1/1	10.110.6.1/24
Router B	GE3/1/1	10.110.1.1/24		S4/1/9/1:0	192.168.3.2/24
	POS5/1/1	192.168.1.1/24		Loop0	3.3.3.3/32
	Loop0	1.1.1.1/32	Router F	GE3/1/1	10.110.6.2/24
Router C	GE3/1/1	10.110.4.1/24		GE3/1/2	10.110.7.1/24
	S4/1/9/1:0	192.168.3.1/24	Source 1	—	10.110.2.100/24
	POS5/1/1	192.168.1.2/24	Source 2	—	10.110.5.100/24
	Loop0	2.2.2.2/32

Configuration procedure

1. Assign IP addresses and unicast routing:

Assign an IP address and subnet mask for each interface as per Figure 5. (Details not shown)

Configure OSPF for interconnection between routers in each AS. Ensure the network-layer interoperation in each AS, and ensure the dynamic update of routing information between the routers through a unicast routing protocol. (Details not shown)

2. Enable IP multicast routing, enable PIM-SM and IGMP, and configure a PIM-SM domain border:

# Enable IP multicast routing on Router A, enable PIM-SM on each interface, and enable IGMP on the host-side interface GigabitEthernet 3/1/3.

<RouterA> system-view

[RouterA] multicast routing-enable

[RouterA] interface GigabitEthernet 3/1/1

[RouterA-GigabitEthernet3/1/1] pim sm

[RouterA-GigabitEthernet3/1/1] quit

[RouterA] interface GigabitEthernet 3/1/2

[RouterA-GigabitEthernet3/1/2] pim sm

[RouterA-GigabitEthernet3/1/2] quit

[RouterA] interface GigabitEthernet 3/1/3

[RouterA-GigabitEthernet3/1/3] igmp enable

[RouterA-GigabitEthernet3/1/3] pim sm

[RouterA-GigabitEthernet3/1/3] quit

The configuration on Router B, Router C, Router D, Router E, and Router F is similar to the configuration on Router A.

# Configure a PIM domain border on Router B.

[RouterB] interface pos 5/1/1

[RouterB-Pos5/1/1] pim sm

[RouterB-Pos5/1/1] pim bsr-boundary

[RouterB-Pos5/1/1] quit

The configuration on Router C and Router E is similar to the configuration on Router B.

3. Configure the position of C-BSR and C-RP:

# Configure Loopback 0 as a C-BSR and a C-RP on Router B.

[RouterB] interface loopback 0

[RouterB-LoopBack0] ip address 1.1.1.1 255.255.255.255

[RouterB-LoopBack0] pim sm

[RouterB-LoopBack0] quit

[RouterB] pim

[RouterB-pim] c-bsr loopback 0

[RouterB-pim] c-rp loopback 0

[RouterB-pim] quit

The configuration on Router C and Router E is similar to the configuration on Router B.

4. Configure BGP and configure mutual route redistribution between BGP and OSPF:

# Configure an EBGP peer, and redistribute OSPF routes on Router B.

[RouterB] bgp 100

[RouterB-bgp] router-id 1.1.1.1

[RouterB-bgp] peer 192.168.1.2 as-number 200

[RouterB-bgp] import-route ospf 1

[RouterB-bgp] quit

# Configure an EBGP peer, and redistribute OSPF routes on Router C.

[RouterC] bgp 200

[RouterC-bgp] router-id 2.2.2.2

[RouterC-bgp] peer 192.168.1.1 as-number 100

[RouterC-bgp] import-route ospf 1

[RouterC-bgp] quit

# Redistribute BGP routing information into OSPF on Router B.

[RouterB] ospf 1

[RouterB-ospf-1] import-route bgp

[RouterB-ospf-1] quit

# Redistribute BGP routing information into OSPF on Router C.

[RouterC] ospf 1

[RouterC-ospf-1] import-route bgp

[RouterC-ospf-1] quit

5. Configure MSDP peers:

# Configure an MSDP peer on Router B.

[RouterB] msdp

[RouterB-msdp] peer 192.168.1.2 connect-interface pos 5/1/1

[RouterB-msdp] quit

# Configure MSDP peers on Router C.

[RouterC] msdp

[RouterC-msdp] peer 192.168.1.1 connect-interface pos 5/1/1

[RouterC-msdp] peer 192.168.3.2 connect-interface serial 4/1/9/1:0

[RouterC-msdp] quit

# Configure an MSDP peer on Router E.

[RouterE] msdp

[RouterE-msdp] peer 192.168.3.1 connect-interface serial 4/1/9/1:0

[RouterE-msdp] quit

6. Verify the configuration:

# Display information about BGP peering relationship on Router B.

[RouterB] display bgp peer

BGP local router ID : 1.1.1.1

Local AS number : 100

Total number of peers : 1 Peers in established state : 1

Peer AS MsgRcvd MsgSent OutQ PrefRcv Up/Down State

192.168.1.2 200 24 21 0 6 00:13:09 Established

# Display information about BGP peering relationship on Router C.

[RouterC] display bgp peer

BGP local router ID : 2.2.2.2

Local AS number : 200

Total number of peers : 1 Peers in established state : 1

Peer AS MsgRcvd MsgSent OutQ PrefRcv Up/Down State

192.168.1.1 100 18 16 0 1 00:12:04 Established

192.168.3.2 200 21 20 0 6 00:12:05 Established

# Display BGP routing table information on Router C.

[RouterC] display bgp routing-table

Total Number of Routes: 5

BGP Local router ID is 2.2.2.2

Status codes: * - valid, ^ - VPNv4 best, > - best, d - damped,

h - history, i - internal, s - suppressed, S - Stale

Origin : i - IGP, e - EGP, ? - incomplete

Network NextHop MED LocPrf PrefVal Path/Ogn

* > 1.1.1.1/32 192.168.1.1 0 0 100?

* >i 2.2.2.2/32 0.0.0.0 0 0 ?

* > 192.168.1.0 0.0.0.0 0 0 ?

* > 192.168.1.1/32 0.0.0.0 0 0 ?

* > 192.168.1.2/32 0.0.0.0 0 0 ?

When multicast sources Source 1 in PIM-SM 1 and Source 2 in PIM-SM 2 send multicast information, receivers in PIM-SM 1 and PIM-SM 3 can receive the multicast data. You can use the display msdp brief command to view the brief information of MSDP peering relationships between the routers. For example:

# Display brief information about MSDP peering relationship on Router B.

[RouterB] display msdp brief

MSDP Peer Brief Information of VPN-Instance: public net

Configured Up Listen Connect Shutdown Down

1 1 0 0 0 0

Peer's Address State Up/Down time AS SA Count Reset Count

192.168.1.2 Up 00:12:27 200 13 0

# View the brief information about MSDP peering relationship on Router C.

[RouterC] display msdp brief

MSDP Peer Brief Information of VPN-Instance: public net

Configured Up Listen Connect Shutdown Down

2 2 0 0 0 0

Peer's Address State Up/Down time AS SA Count Reset Count

192.168.3.2 Up 00:15:32 200 8 0

192.168.1.1 UP 00:06:39 100 13 0

# Display brief information about MSDP peering relationship on Router E.

[RouterE] display msdp brief

MSDP Peer Brief Information of VPN-Instance: public net

Configured Up Listen Connect Shutdown Down

1 1 0 0 0 0

Peer's Address State Up/Down time AS SA Count Reset Count

192.168.3.1 Up 01:07:08 200 8 0

# Display brief information about MSDP peering relationships on Router B.

[RouterB] display msdp peer-status

MSDP Peer Information of VPN-Instance: public net

MSDP Peer 192.168.1.2, AS 200

Description:

Information about connection status:

State: Up

Up/down time: 00:15:47

Resets: 0

Connection interface: Pos5/1/1 (192.168.1.1)

Number of sent/received messages: 16/16

Number of discarded output messages: 0

Elapsed time since last connection or counters clear: 00:17:51

Information about (Source, Group)-based SA filtering policy:

Import policy: none

Export policy: none

Information about SA-Requests:

Policy to accept SA-Request messages: none

Sending SA-Requests status: disable

Minimum TTL to forward SA with encapsulated data: 0

SAs learned from this peer: 13, SA-cache maximum for the peer: 8192

Input queue size: 0, Output queue size: 0

Counters for MSDP message:

Count of RPF check failure: 0

Incoming/outgoing SA messages: 13/0

Incoming/outgoing SA requests: 0/0

Incoming/outgoing SA responses: 0/0

Incoming/outgoing data packets: 0/0

Inter-AS multicast configuration by leveraging static RPF peers

Network requirements

As shown in Figure 6, the network has two OSPF ASs: AS 100 and AS 200. BGP runs between the two ASs.

PIM-SM 1 belongs to AS 100, and PIM-SM 2 and PIM-SM 3 belong to AS 200. Each PIM-SM domain has at least one multicast source or receiver.

Configure Loopback 0 as the C-BSR and C-RP of the related PIM-SM domain on Router A, Router D and Router G.

According to the RPF principle, the routers can receive SA messages that pass the filtering policy from its static RPF peers. To share multicast source information among PIM-SM domains without changing the unicast topology structure, configure MSDP peering relationships for the RPs of the PIM-SM domains and configure static RPF peering relationships for the MSDP peers to share multicast source information among the PIM-SM domains.

Figure 6 Network diagram

Device	Interface	IP address	Device	Interface	IP address
Source 1	-	192.168.1.100/24	Router D	GE3/1/1	10.110.5.1/24
Source 2	-	192.168.3.100/24		POS5/1/1	10.110.3.2/24
Router A	GE3/1/1	10.110.1.1/24		Loop0	2.2.2.2/32
	GE3/1/2	10.110.2.1/24	Router E	GE3/1/1	10.110.5.2/24
	Loop0	1.1.1.1/32		GE3/1/2	192.168.3.1/24
Router B	GE3/1/1	10.110.1.2/24	Router F	GE3/1/1	10.110.6.1/24
	GE3/1/2	192.168.1.1/24		S2/1/9/1:0	10.110.4.2/24
	POS5/1/1	10.110.3.1/24	Router G	GE3/1/1	10.110.6.2/24
Router C	GE3/1/1	10.110.2.2/24		GE3/1/2	192.168.4.1/24
	GE3/1/2	192.168.2.1/24		Loop0	3.3.3.3/32
	S2/1/9/1:0	10.110.4.1/24

Configuration procedure

1. Assign IP addresses and unicast routing:

Assign an IP address and subnet mask for each interface as per Figure 6. (Details not shown)

Configure OSPF for interconnection between the routers in each AS. Ensure the network-layer interoperation in each AS, and ensure the dynamic update of routing information through a unicast routing protocol among the routers. (Details not shown)

2. Enable IP multicast routing, enable PIM-SM and IGMP, and configure a PIM-SM domain border:

# Enable IP multicast routing on Router C, enable PIM-SM on each interface, and enable IGMP on the host-side interface GigabitEthernet 3/1/2.

<RouterC> system-view

[RouterC] multicast routing-enable

[RouterC] interface GigabitEthernet 3/1/1

[RouterC-GigabitEthernet3/1/1] pim sm

[RouterC-GigabitEthernet3/1/1] quit

[RouterC] interface GigabitEthernet 3/1/2

[RouterC-GigabitEthernet3/1/2] igmp enable

[RouterC-GigabitEthernet3/1/2] pim sm

[RouterC-GigabitEthernet3/1/2] quit

[RouterC] interface serial 2/1/9/1:0

[RouterC-Serial2/1/9/1:0] pim sm

[RouterC-Serial2/1/9/1:0] quit

The configuration on Router A, Router B, Router D, Router E, Router F, and Router G is similar to that on Router C. (Details not shown)

# Configure PIM domain borders on Router B.

[RouterB] interface pos 5/1/1

[RouterB-Pos5/1/1] pim sm

[RouterB-Pos5/1/1] pim bsr-boundary

[RouterB-Pos5/1/1] quit

The configuration on Router C, Router D, and Router F is similar to that on Router B. (Details not shown)

3. Configure C-BSRs and C-RPs:

# Configure Loopback 0 as a C-BSR and a C-RP on Router A.

[RouterA] pim

[RouterA-pim] c-bsr loopback 0

[RouterA-pim] c-rp loopback 0

[RouterA-pim] quit

The configuration on Router D and Router G is similar to that on Router A. (Details not shown)

4. Configure BGP, and redistribute BGP routing information into OSPF and OSPF routing information into BGP:

# Configure an EBGP peer, and redistribute OSPF routing information on Router B.

[RouterB] bgp 100

[RouterB-bgp] router-id 1.1.1.2

[RouterB-bgp] peer 10.110.3.2 as-number 200

[RouterB-bgp] import-route ospf 1

[RouterB-bgp] quit

# Configure an EBGP peer, and redistribute OSPF routing information on Router D.

[RouterD] bgp 200

[RouterD-bgp] router-id 2.2.2.2

[RouterD-bgp] peer 10.110.3.1 as-number 100

[RouterD-bgp] import-route ospf 1

[RouterD-bgp] quit

# Configure an EBGP peer, and redistribute OSPF routing information on Router C.

[RouterC] bgp 100

[RouterC-bgp] router-id 1.1.1.3

[RouterC-bgp] peer 10.110.4.2 as-number 200

[RouterC-bgp] import-route ospf 1

[RouterC-bgp] quit

# Configure an EBGP peer, and redistribute OSPF routing information on Router F.

[RouterF] bgp 200

[RouterF-bgp] router-id 3.3.3.1

[RouterF-bgp] peer 10.110.4.1 as-number 100

[RouterF-bgp] import-route ospf 1

[RouterF-bgp] quit

# Redistribute BGP routing information into OSPF on Router B.

[RouterB] ospf 1

[RouterB-ospf-1] import-route bgp

[RouterB-ospf-1] quit

# Redistribute BGP routing information into OSPF on Router D.

[RouterD] ospf 1

[RouterD-ospf-1] import-route bgp

[RouterD-ospf-1] quit

# Redistribute BGP routing information into OSPF on Router C.

[RouterC] ospf 1

[RouterC-ospf-1] import-route bgp

[RouterC-ospf-1] quit

# Redistribute BGP routing information into OSPF on Router F.

[RouterF] ospf 1

[RouterF-ospf-1] import-route bgp

[RouterF-ospf-1] quit

5. Configure MSDP peers and static RPF peers:

# Configure Router D and Router G as the MSDP peers and static RPF peers of Router A.

[RouterA] ip ip-prefix list-dg permit 10.110.0.0 16 greater-equal 16 less-equal 32

[RouterA] msdp

[RouterA-msdp] peer 10.110.3.2 connect-interface GigabitEthernet 3/1/1

[RouterA-msdp] peer 10.110.6.2 connect-interface GigabitEthernet 3/1/2

[RouterA-msdp] static-rpf-peer 10.110.3.2 rp-policy list-dg

[RouterA-msdp] static-rpf-peer 10.110.6.2 rp-policy list-dg

[RouterA-msdp] quit

# Configure Router A as the MSDP peer and static RPF peer of Router D.

[RouterD] ip ip-prefix list-a permit 10.110.0.0 16 greater-equal 16 less-equal 32

[RouterD] msdp

[RouterD-msdp] peer 10.110.1.1 connect-interface pos 5/1/1

[RouterD-msdp] static-rpf-peer 10.110.1.1 rp-policy list-a

[RouterD-msdp] quit

# Configure Router A as the MSDP peer and static RPF peer of Router G.

[RouterG] ip ip-prefix list-a permit 10.110.0.0 16 greater-equal 16 less-equal 32

[RouterG] msdp

[RouterG-msdp] peer 10.110.2.1 connect-interface GigabitEthernet 3/1/1

[RouterG-msdp] static-rpf-peer 10.110.2.1 rp-policy list-a

[RouterG-msdp] quit

6. Verify the configuration:

Use the display bgp peer command to display the BGP peering relationships between the routers. Router A does not display any information, which means that no BGP peering relationship has been established between Router A and Router D, or between Router A and Router G.

When the multicast source in PIM-SM 1 (Source 1) and the multicast source in PIM-SM 2 (Source 2) send multicast information, receivers in PIM-SM 1 and PIM-SM 3 can receive the multicast data. You can use the display msdp brief command to view the brief information of MSDP peering relationships between the routers. For example:

# Display brief MSDP peer information on Router A.

[RouterA] display msdp brief

MSDP Peer Brief Information of VPN-Instance: public net

Configured Up Listen Connect Shutdown Down

2 2 0 0 0 0

Peer's Address State Up/Down time AS SA Count Reset Count

10.110.3.2 Up 01:07:08 ? 8 0

10.110.6.2 Up 00:16:39 ? 13 0

# Display brief MSDP peer information on Router D.

[RouterD] display msdp brief

MSDP Peer Brief Information of VPN-Instance: public net

Configured Up Listen Connect Shutdown Down

1 1 0 0 0 0

Peer's Address State Up/Down time AS SA Count Reset Count

10.110.1.1 Up 01:07:09 ? 8 0

# Display brief MSDP peer information on Router G.

[RouterG] display msdp brief

MSDP Peer Brief Information of VPN-Instance: public net

Configured Up Listen Connect Shutdown Down

1 1 0 0 0 0

Peer's Address State Up/Down time AS SA Count Reset Count

10.110.2.1 Up 00:16:40 ? 13 0

Anycast RP configuration

Network requirements

The PIM-SM domain in this example has multiple multicast sources and receivers. OSPF runs within the domain to provide unicast routes.

Configure the Anycast RP application so that the receiver-side DRs and the source-side DRs can initiate a Join message to their respective RPs that are the topologically nearest to them.

On Router B and Router D, configure the interface Loopback 10 as a C-BSR, and Loopback 20 as a C-RP.

The router ID of Router B is 1.1.1.1, while the router ID of Router D is 2.2.2.2. Set up an MSDP peering relationship between Router B and Router D.

Figure 7 Network diagram

Device	Interface	IP address	Device	Interface	IP address
Source 1	—	10.110.5.100/24	Router C	POS5/1/1	192.168.1.2/24
Source 2	—	10.110.6.100/24		POS5/1/2	192.168.2.2/24
Router A	GE3/1/1	10.110.5.1/24	Router D	GE3/1/1	10.110.3.1/24
Router A	S4/1/9/1:0	10.110.2.2/24	Router D	GE3/1/1	10.110.3.1/24
Router B	GE3/1/1	10.110.1.1/24		S4/1/9/1:0	10.110.4.1/24
	S4/1/9/1:0	10.110.2.1/24		POS5/1/1	192.168.2.1/24
	POS5/1/1	192.168.1.1/24		Loop0	2.2.2.2/32
	Loop0	1.1.1.1/32		Loop10	4.4.4.4/32
	Loop10	3.3.3.3/32		Loop20	10.1.1.1/32
	Loop20	10.1.1.1/32	Router E	GE3/1/1	10.110.6.1/24
	Loop20	10.1.1.1/32	Router E	S4/1/9/1:0	10.110.4.2/24

Configuration procedure

1. Assign IP addresses and unicast routing:

Assign an IP address and subnet mask for each interface as per Figure 7. (Details not shown)

Configure OSPF for interconnection between the routers in the PIM-SM domain. Ensure the network-layer interoperation among the routers, and ensure the dynamic update of routing information through a unicast routing protocol. (Details not shown)

2. Enable IP multicast routing, and enable PIM-SM and IGMP:

# Enable IP multicast routing on Router B, enable PIM-SM on each interface, and enable IGMP on the host-side interface GigabitEthernet3/1/1.

<RouterB> system-view

[RouterB] multicast routing-enable

[RouterB] interface GigabitEthernet3/1/1

[RouterB-GigabitEthernet3/1/1] igmp enable

[RouterB-GigabitEthernet3/1/1] pim sm

[RouterB-GigabitEthernet3/1/1] quit

[RouterB] interface serial 4/1/9/1:0

[RouterB-Serial4/1/9/1:0] pim sm

[RouterB-Serial4/1/9/1:0] quit

[RouterB] interface pos 5/1/1

[RouterB-Pos5/1/1] pim sm

[RouterB-Pos5/1/1] quit

[RouterB] interface loopback 0

[RouterB-LoopBack0] pim sm

[RouterB-LoopBack0] quit

[RouterB] interface loopback 10

[RouterB-LoopBack10] pim sm

[RouterB-LoopBack10] quit

[RouterB] interface loopback 20

[RouterB-LoopBack20] pim sm

[RouterB-LoopBack20] quit

The configuration on Router A, Router C, Router D, and Router E is similar to the configuration on Router B.

3. Configure the position of C-BSR and C-RP:

# Configure Loopback 10 as a C-BSR and Loopback 20 as a C-RP on Router B.

[RouterB] pim

[RouterB-pim] c-bsr loopback 10

[RouterB-pim] c-rp loopback 20

[RouterB-pim] quit

The configuration on Router D is similar to the configuration on Router B.

4. Configure MSDP peers:

# Configure an MSDP peer on Loopback 0 of Router B.

[RouterB] msdp

[RouterB-msdp] originating-rp loopback 0

[RouterB-msdp] peer 2.2.2.2 connect-interface loopback 0

[RouterB-msdp] quit

# Configure an MSDP peer on Loopback 0 of Router D.

[RouterD] msdp

[RouterD-msdp] originating-rp loopback 0

[RouterD-msdp] peer 1.1.1.1 connect-interface loopback 0

[RouterD-msdp] quit

5. Verify the configuration:

You can use the display msdp brief command to view the brief information of MSDP peering relationships between the routers.

# Display brief MSDP peer information on Router B.

[RouterB] display msdp brief

MSDP Peer Brief Information of VPN-Instance: public net

Configured Up Listen Connect Shutdown Down

1 1 0 0 0 0

Peer's Address State Up/Down time AS SA Count Reset Count

2.2.2.2 Up 00:10:17 ? 0 0

# Display brief MSDP peer information on Router D.

[RouterD] display msdp brief

MSDP Peer Brief Information of VPN-Instance: public net

Configured Up Listen Connect Shutdown Down

1 1 0 0 0 0

Peer's Address State Up/Down time AS SA Count Reset Count

1.1.1.1 Up 00:10:18 ? 0 0

To view the PIM routing information on each router, use the display pim routing-table command.

When Source 1 (10.110.5.100/24) sends multicast data to multicast group G (225.1.1.1), Host A joins multicast group G. By comparing the PIM routing information displayed on Router B with that displayed on Router D, you can see that Router B acts now as the RP for Source 1 and Host A.

# Display PIM routing information on Router B.

[RouterB] display pim routing-table

VPN-Instance: public net

Total 1 (*, G) entry; 1 (S, G) entry

(*, 225.1.1.1)

RP: 10.1.1.1 (local)

Protocol: pim-sm, Flag: WC

UpTime: 00:15:04

Upstream interface: Register

Upstream neighbor: NULL

RPF prime neighbor: NULL

Downstream interface(s) information:

Total number of downstreams: 1

1: GigabitEthernet3/1/1

Protocol: igmp, UpTime: 00:15:04, Expires: -

(10.110.5.100, 225.1.1.1)

RP: 10.1.1.1 (local)

Protocol: pim-sm, Flag: SPT 2MSDP ACT

UpTime: 00:46:28

Upstream interface: Serial4/1/9/1:0

Upstream neighbor: 10.110.2.2

RPF prime neighbor: 10.110.2.2

Downstream interface(s) information:

Total number of downstreams: 1

1: GigabitEthernet3/1/1

Protocol: pim-sm, UpTime: - , Expires: -

# Display PIM routing information on Router D.

[RouterD] display pim routing-table

No information is output on Router D.

Host A has left multicast group G, and Source 1 has stopped sending multicast data to multicast group G. When Source 2 (10.110.6.100/24) sends multicast data to G, Host B joins G. By comparing the PIM routing information displayed on Router B with that displayed on Router D, you can see that Router D acts now as the RP for Source 2 and Host B.

# Display PIM routing information on Router B.

[RouterB] display pim routing-table

No information is output on Router B.

# Display PIM routing information on Router D.

[RouterD] display pim routing-table

VPN-Instance: public net

Total 1 (*, G) entry; 1 (S, G) entry

(*, 225.1.1.1)

RP: 10.1.1.1 (local)

Protocol: pim-sm, Flag: WC

UpTime: 00:12:07

Upstream interface: Register

Upstream neighbor: NULL

RPF prime neighbor: NULL

Downstream interface(s) information:

Total number of downstreams: 1

1: GigabitEthernet3/1/1

Protocol: igmp, UpTime: 00:12:07, Expires: -

(10.110.6.100, 225.1.1.1)

RP: 10.1.1.1 (local)

Protocol: pim-sm, Flag: SPT 2MSDP ACT

UpTime: 00:40:22

Upstream interface: Serial4/1/9/1:0

Upstream neighbor: 10.110.4.2

RPF prime neighbor: 10.110.4.2

Downstream interface(s) information:

Total number of downstreams: 1

1: GigabitEthernet3/1/1

Protocol: pim-sm, UpTime: - , Expires: -

SA message filtering configuration

Network requirements

There are three PIM-SM domains, with OSPF running within each domain and among these domains to provide unicast routes.

Loopback 0 of Router A, Router C, and Router D are configured as a C-BSR and a C-RP of the PIM-SM domains respectively.

Set up MSDP peering relationships between Router A and Router C and between Router C and Router D.

Multicast source Source 1 sends multicast data to multicast groups 225.1.1.0/30 and 226.1.1.0/30; Source 2 sends multicast data to 227.1.1.0/30.

Configure SA message filtering rules so that Host A and Host B can receive only the multicast data for 225.1.1.0/30 and 226.1.1.0/30, and Host C can receive only the multicast data for 226.1.1.0/30 and 227.1.1.0/30.

Figure 8 Network diagram

Device	Interface	IP address	Device	Interface	IP address
Source 1	—	10.110.3.100/24	Router C	GE3/1/1	10.110.4.1/24
Source 2	—	10.110.6.100/24		S4/1/9/1:0	10.110.5.1/24
Router A	GE3/1/1	10.110.1.1/24		POS5/1/1	192.168.1.2/24
	S4/1/9/1:0	10.110.2.1/24		POS5/1/2	192.168.2.2/24
	POS5/1/1	192.168.1.1/24		Loop0	2.2.2.2/32
	Loop0	1.1.1.1/32	Router D	GE3/1/1	10.110.6.1/24
Router B	GE3/1/1	10.110.3.1/24		GE3/1/2	10.110.7.1/24
	S4/1/9/1:0	10.110.2.2/24		S4/1/9/1:0	10.110.5.2/24
	POS5/1/1	192.168.2.1/24		Loop0	3.3.3.3/32

Configuration procedure

1. Assign IP addresses and unicast routing:

Assign an IP address and subnet mask for each interface as per Figure 8. (Details not shown)

Configure OSPF for interconnection between the routers in each PIM-SM domain. Ensure the network-layer interoperation among the routers, and ensure the dynamic update of routing information through by leveraging unicast routes. (Details not shown)

2. Enable IP multicast routing, enable PIM-SM and IGMP, and configure a PIM-SM domain border:

# On Router A, enable IP multicast routing, enable PIM-SM on each interface, and enable IGMP on the host-side interface GigabitEthernet 3/1/1.

<RouterA> system-view

[RouterA] multicast routing-enable

[RouterA] interface GigabitEthernet 3/1/1

[RouterA-GigabitEthernet3/1/1] igmp enable

[RouterA-GigabitEthernet3/1/1] pim sm

[RouterA-GigabitEthernet3/1/1] quit

[RouterA] interface serial 4/1/9/1:0

[RouterA-Serial4/1/9/1:0] pim sm

[RouterA-Serial4/1/9/1:0] quit

[RouterA] interface pos 5/1/1

[RouterA-Pos5/1/1] pim sm

[RouterA-Pos5/1/1] quit

[RouterA] interface loopback 0

[RouterA-LoopBack0] pim sm

[RouterA-LoopBack0] quit

The configuration on Router B, Router C, and Router D is similar to the configuration on Router A.

# Configure PIM domain borders on Router C.

[RouterC] interface pos 5/1/1

[RouterC-Pos5/1/1] pim sm

[RouterC-Pos5/1/1] pim bsr-boundary

[RouterC-Pos5/1/1] quit

[RouterC] interface pos 5/1/2

[RouterC-Pos5/1/2] pim sm

[RouterC-Pos5/1/2] pim bsr-boundary

[RouterC-Pos5/1/2] quit

[RouterC] interface serial 4/1/9/1:0

[RouterC-Serial4/1/9/1:0] pim sm

[RouterC-Serial4/1/9/1:0] pim bsr-boundary

[RouterC-Serial4/1/9/1:0] quit

The configuration on Router A, Router B, and Router D is similar to the configuration on Router C.

3. Configure the position of the C-BSR and C-RP:

# Configure Loopback 0 to serve as a C-BSR and C-RP on Router A.

[RouterA] pim

[RouterA-pim] c-bsr loopback 0

[RouterA-pim] c-rp loopback 0

[RouterA-pim] quit

The configuration on Router C and Router D is similar to the configuration on Router A.

4. Configure MSDP peers:

# Configure an MSDP peer on Router A.

[RouterA] msdp

[RouterA-msdp] peer 192.168.1.2 connect-interface pos 5/1/1

[RouterA-msdp] quit

# Configure MSDP peers on Router C.

[RouterC] msdp

[RouterC-msdp] peer 192.168.1.1 connect-interface pos 5/1/1

[RouterC-msdp] peer 10.110.5.2 connect-interface serial 4/1/9/1:0

[RouterC-msdp] quit

# Configure an MSDP peer on Router D.

[RouterD] msdp

[RouterD-msdp] peer 10.110.5.1 connect-interface serial 4/1/9/1:0

[RouterD-msdp] quit

5. Configure SA message filtering rules:

# Configure an SA message filter on Router C so that Router C will not forward SA messages for (Source 1, 225.1.1.0/30) to Router D.

[RouterC] acl number 3001

[RouterC-acl-adv-3001] rule deny ip source 10.110.3.100 0 destination 225.1.1.0 0.0.0.3

[RouterC-acl-adv-3001] rule permit ip source any destination any

[RouterC-acl-adv-3001] quit

[RouterC] msdp

[RouterC-msdp] peer 10.110.5.2 sa-policy export acl 3001

[RouterC-msdp] quit

# Configure an SA message filter on Router D so that Router D will not create SA messages for Source 2.

[RouterD] acl number 2001

[RouterD-acl-basic-2001] rule deny source 10.110.6.100 0

[RouterD-acl-basic-2001] quit

[RouterD] msdp

[RouterD-msdp] import-source acl 2001

[RouterD-msdp] quit

6. Verify the configuration:

# Display the (S, G) entries in the SA cache on Router C.

[RouterC] display msdp sa-cache

MSDP Source-Active Cache Information of VPN-Instance: public net

MSDP Total Source-Active Cache - 8 entries

MSDP matched 8 entries

(Source, Group) Origin RP Pro AS Uptime Expires

(10.110.3.100, 225.1.1.0) 1.1.1.1 ? ? 02:03:30 00:05:31

(10.110.3.100, 225.1.1.1) 1.1.1.1 ? ? 02:03:30 00:05:31

(10.110.3.100, 225.1.1.2) 1.1.1.1 ? ? 02:03:30 00:05:31

(10.110.3.100, 225.1.1.3) 1.1.1.1 ? ? 02:03:30 00:05:31

(10.110.3.100, 226.1.1.0) 1.1.1.1 ? ? 02:03:30 00:05:31

(10.110.3.100, 226.1.1.1) 1.1.1.1 ? ? 02:03:30 00:05:31

(10.110.3.100, 226.1.1.2) 1.1.1.1 ? ? 02:03:30 00:05:31

(10.110.3.100, 226.1.1.3) 1.1.1.1 ? ? 02:03:30 00:05:31

# Display the (S, G) forwarding entries in the SA cache on Router D.

[RouterD] display msdp sa-cache

MSDP Source-Active Cache Information of VPN-Instance: public net

MSDP Total Source-Active Cache - 4 entries

MSDP matched 4 entries

(Source, Group) Origin RP Pro AS Uptime Expires

(10.110.3.100, 226.1.1.0) 1.1.1.1 ? ? 00:32:53 00:05:07

(10.110.3.100, 226.1.1.1) 1.1.1.1 ? ? 00:32:53 00:05:07

(10.110.3.100, 226.1.1.2) 1.1.1.1 ? ? 00:32:53 00:05:07

(10.110.3.100, 226.1.1.3) 1.1.1.1 ? ? 00:32:53 00:05:07

Troubleshooting MSDP

MSDP peers stay in down state

Symptom

The configured MSDP peers stay in down state.

Analysis

· A TCP connection–based MSDP peering relationship is established between the local interface address and the MSDP peer after the configuration.

· The TCP connection setup will fail if the local interface address is not consistent with the MSDP peer address configured on the peer router.

· If no route is available between the MSDP peers, the TCP connection setup will fail.

Solution

1. Use the display ip routing-table command to verify that the unicast route between the routers is correct.

2. Verify that a unicast route is available between the two routers that will become MSDP peers to each other.

3. Use the display current-configuration command to verify that the local interface address and the MSDP peer address of the remote router are the same.

No SA entries exist in the router’s SA cache

Symptom

MSDP fails to send (S, G) entries through SA messages.

Analysis

· The import-source command controls sending (S, G) entries through SA messages to MSDP peers. If this command is executed without the acl-number argument, all the (S, G) entries will be filtered off. Namely, no (S, G) entries of the local domain will be advertised.

· If you do not configure the import-source command, the system advertises all the (S, G) entries of the local domain. If MSDP fails to send (S, G) entries through SA messages, verify that the import-source command has been correctly configured.

Solution

1. Use the display ip routing-table command to verify that the unicast route between the routers is correct.

2. Verify that a unicast route is available between the two routers that will become MSDP peers to each other.

3. Verify the configuration of the import-source command and its acl-number argument and make sure that ACL rule can filter appropriate (S, G) entries.

Inter-RP communication faults in Anycast RP application

Symptom

RPs fail to exchange their locally registered (S, G) entries with one another in the Anycast RP application.

Analysis

· In the Anycast RP application, RPs in the same PIM-SM domain are configured to be MSDP peers to achieve load balancing among the RPs.

· An MSDP peer address must be different from the Anycast RP address, and the C-BSR and C-RP must be configured on different devices or interfaces.

· If you configure the originating-rp command, MSDP replaces the RP address in the SA messages with the address of the interface specified in the command.

· When an MSDP peer receives an SA message, it performs RPF check on the message. If the MSDP peer finds that the remote RP address is the same as the local RP address, it will discard the SA message.

Solution

1. Use the display ip routing-table command to verify that the unicast route between the routers is correct.

2. Verify that a unicast route is available between the two routers that will become MSDP peer to each other.

3. Verify the configuration of the originating-rp command. In the Anycast RP application environment, use the originating-rp command to configure the RP address in the SA messages, which must be the local interface address.

4. Verify that the C-BSR address is different from the Anycast RP address.

07-IP Multicast Configuration Guide

MSDP overview

MSDP peers

Inter-domain multicast delivery through MSDP

RPF check rules for SA messages

Intra-domain Anycast RP through MSDP

Multi-instance MSDP

MSDP configuration task list

Configuring basic functions of MSDP

Enabling MSDP

Enabling MSDP globally on the public network

Enabling MSDP in a VPN instance

Creating an MSDP peer connection

Configuring a static RPF peer

Configuring an MSDP peer connection

Configuring MSDP peer description

Configuring an MSDP mesh group

Configuring MSDP peer connection control

Configuring SA messages related parameters

Configuring SA message content

Configuring SA request messages

Configuring the SA cache mechanism

Displaying and maintaining MSDP

MSDP configuration examples

Network requirements

Configuration procedure

Inter-AS multicast configuration by leveraging static RPF peers

Network requirements

Configuration procedure

Network requirements

Configuration procedure

SA message filtering configuration

Network requirements

Configuration procedure

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Analysis

Solution

Symptom

Analysis

Solution

Symptom

Analysis

Solution

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