MSDP

MSDP

To view MSDP peer status, use

RouterA# show ip msdp peer

MSDP Peer 192.168.1.2 (?), AS 200

Connection status:

State: Up, Resets: 1, Connection source: none configured

Uptime(Downtime): 01:03:44, Messages sent/received: 72/71

Output messages discarded: 0

Connection and counters cleared 01:15:14 ago

SA Filtering:

Input (S,G) filter: none, route-map: none

Input RP filter: none, route-map: none

Output (S,G) filter: none, route-map: none

Output RP filter: none, route-map: none

SA-Requests:

Input filter: none

Peer ttl threshold: 0

SAs learned from this peer: 0

Input queue size: 0, Output queue size: 0

Message counters:

RPF Failure count: 0

SA Messages in/out: 23/18

SA Requests in: 0

SA Responses out: 0

Data Packets in/out: 5/6

Suppose RouterB already has a non-empty outgoing interface list for (*, 239.1.1.1) entry due to a member in the domain for group 239.1.1.1.

Now the source connected to PIM-DR starts sourcing multicast traffic for group 239.1.1.1. The DR connected to the source sends Register message to the RP. The RP sends Register-Stop message back to the DR. The RP also creates an SA message as (10.1.1.1, 239.1.1.1) with RP address as 2.2.2.2 and sends the SA message to its MSDP peer RouterB. Here, the RP address received by RouterB is 192.168.1.1. This is because RouterA sends the SA message to RouterB using its outgoing interface. To change this default behaviour, the ip msdp originator-id command can be used.

RouterB# show ip msdp sa-cache

MSDP Source-Active Cache - 1 entries

(10.1.1.1, 239.1.1.1), RP 192.168.1.1, MBGP/AS 200, 00:21:19/00:05:07, Peer 192.168.1.1

The mroute table on RouterA indicates that (10.1.1.1, 239.1.1.1) entry is a candidate to be advertised to its MSDP peer RouterB indicated by flag "A".

RouterA# show ip mroute

IP Multicast Routing Table

Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,

L - Local, P - Pruned, R - RP-bit set, F - Register flag,

T - SPT-bit set, J - Join SPT, M - MSDP created entry,

X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,

U - URD, I - Received Source Specific Host Report,

Z - Multicast Tunnel, z - MDT-data group sender,

Y - Joined MDT-data group, y - Sending to MDT-data group

Outgoing interface flags: H - Hardware switched, A - Assert winner

Timers: Uptime/Expires

Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 239.1.1.1), 00:00:08/stopped, RP 2.2.2.2, flags: SP

Incoming interface: Null, RPF nbr 0.0.0.0

Outgoing interface list: Null

(10.1.1.1, 239.1.1.1), 00:00:08/00:02:51, flags: TA

Incoming interface: FastEthernet0/0, RPF nbr 172.16.1.1

Outgoing interface list:

Serial0/0, Forward/Sparse, 00:00:07/00:03:22

Since RouterB has non-empty OIL for (*, 239.1.1.1), it creates an (S, G) entry i.e. (10.1.1.1, 239.1.1.1) in its multicast routing table with RPF neighbor as its MSDP peer and RPF interface as the Serial 0/0. It then forwards the multicast traffic to the receiver over its outgoing interface. The flag "M" indicates that the entry is learned via MSDP.

RouterB# show ip mroute

IP Multicast Routing Table

Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,

L - Local, P - Pruned, R - RP-bit set, F - Register flag,

T - SPT-bit set, J - Join SPT, M - MSDP created entry,

X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,

U - URD, I - Received Source Specific Host Report,

Z - Multicast Tunnel, z - MDT-data group sender,

Y - Joined MDT-data group, y - Sending to MDT-data group

Outgoing interface flags: H - Hardware switched, A - Assert winner

Timers: Uptime/Expires

Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 239.1.1.1), 00:23:42/00:03:21, RP 3.3.3.3, flags: S

Incoming interface: Null, RPF nbr 0.0.0.0

Outgoing interface list:

FastEthernet0/1, Forward/Sparse, 00:23:42/00:03:21

(10.1.1.1, 239.1.1.1), 00:00:24/00:03:21, flags: MT

Incoming interface: Serial0/0, RPF nbr 192.168.1.1

Outgoing interface list:

FastEthernet0/1, Forward/Sparse, 00:00:24/00:03:21