504 CHAPTER 48: MSDP CONFIGURATIONThat no information is output after you carry out the display bgp peer commandmeans that the BGP peering relationships are not established between theswitches. 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 thedisplay msdp brief command to view the brief information of MSDP peeringrelationships between the switches. The information about MSDP peeringrelationships on Switch C, Switch D and Switch F is as follows:[SwitchC] display msdp briefMSDP Peer Brief InformationPeer’s Address State Up/Down time AS SA Count Reset Count2.2.2.2 UP 01:07:08 ? 8 03.3.3.3 UP 00:16:39 ? 13 0[SwitchD] display msdp briefMSDP Peer Brief InformationPeer’s Address State Up/Down time AS SA Count Reset Count1.1.1.1 UP 01:07:09 ? 8 0[SwitchF] display msdp briefMSDP Peer Brief InformationPeer’s Address State Up/Down time AS SA Count Reset Count1.1.1.1 UP 00:16:40 ? 13 0TroubleshootingMSDP ConfigurationMSDP Peer Always inthe Down StateSymptomAn MSDP peer is configured, but it is always in the down state.AnalysisAn MSDP peer relationship between the locally configured connect-interfaceinterface address and the configured peer address is based on a TCP connection. Ifthe address of local connect-interface interface is inconsistent with the peeraddress configured on the peer router, no TCP connection can be established. Ifthere is no route between the two peers, no TCP connection can be established.Solution1 Check the connectivity of the route between the routers. Use the display iprouting-table command to check that the unicast route between the routers iscorrect.2 Further check that a unicast route exists between two routers that will becomeMSDP peers and that the route leads to the two peers.3 Check that the interface addresses of the MSDP peers are consistent. Use thedisplay current-configuration command to check that the address of the localconnect-interface interface is consistent with the address of the correspondingMSDP peer.No SA Entry in the SACache of the RouterSymptomAn MSDP fails to send (S, G) forwarding entries through an SA message.AnalysisYou can use the import-source command to send the (S, G) entries of the localmulticast domain to the neighboring MSDP peer through SA messages. The acl
