Inter-AS Multicast Using MBGP and MSDP
Both Multiprotocol Border Gateway Protocol (MBGP) connections and MSDP connections are TCP connections. You can set up an MBGP peer relationship between two MSDP peers to ensure that SA messages can pass the RPF check.
As shown in Figure 6-7, the RPs in different PIM-SM domains are not directly connected to each other and the RPs and ASBRs are deployed on different routers. After you set up MSDP peer relationships between the RPs, you can also set up MBGP peer relationships between them to ensure that SA messages can pass the RPF check.
IBGP: set up IBGP peer relationships for RPs in the same AS, such as RP1 and RP2, and RP3 and RP4.
EBGP: set up EBGP peer relationships for RPs in different ASs, such as RP1 and RP3, and RP2 and RP4.
The MBGP peer relationship and MSDP peer relationship must be set up on the same interface. MBGP and MSDP are frequently used together. For details about MBGP, see "BGP" in the NetEngine AR Configuration Guide- IP Routing.