3Com Switch 7750 Configuration Guide

504 CHAPTER 48: MSDP CONFIGURATION
That no information is output after you carry out the display bgp peer command
means that the BGP peering relationships are not established between the
switches. When the multicast source S1 in PIM-SM1 sends multicast information,
receivers in PIM-SM2 and PIM-SM3 can receive the multicast data. You can use the
display msdp brief command to view the brief information of MSDP peering
relationships between the switches. The information about MSDP peering
relationships on Switch C, Switch D and Switch F is as follows:
[SwitchC] display msdp brief
MSDP Peer Brief Information
Peer’s Address State Up/Down time AS SA Count Reset Count
2.2.2.2 UP 01:07:08 ? 8 0
3.3.3.3 UP 00:16:39 ? 13 0
[SwitchD] display msdp brief
MSDP Peer Brief Information
Peer’s Address State Up/Down time AS SA Count Reset Count
1.1.1.1 UP 01:07:09 ? 8 0
[SwitchF] display msdp brief
MSDP Peer Brief Information
Peer’s Address State Up/Down time AS SA Count Reset Count
1.1.1.1 UP 00:16:40 ? 13 0
Troubleshooting
MSDP Configuration
MSDP Peer Always in
the Down State
Symptom
An MSDP peer is configured, but it is always in the down state.
Analysis
An MSDP peer relationship between the locally configured connect-interface
interface address and the configured peer address is based on a TCP connection. If
the address of local connect-interface interface is inconsistent with the peer
address configured on the peer router, no TCP connection can be established. If
there is no route between the two peers, no TCP connection can be established.
Solution
1 Check the connectivity of the route between the routers. Use the display ip
routing-table command to check that the unicast route between the routers is
correct.
2 Further check that a unicast route exists between two routers that will become
MSDP peers and that the route leads to the two peers.
3 Check that the interface addresses of the MSDP peers are consistent. Use the
display current-configuration command to check that the address of the local
connect-interface interface is consistent with the address of the corresponding
MSDP peer.
No SA Entry in the SA
Cache of the Router
Symptom
An MSDP fails to send (S, G) forwarding entries through an SA message.
Analysis
You can use the import-source command to send the (S, G) entries of the local
multicast domain to the neighboring MSDP peer through SA messages. The acl