Operation Manual – MulticastH3C S5600 Series Ethernet Switches Chapter 5 MSDP Configuration5-3multicast source information out of the PIM-SM domain.z Receiver-side MSDP peer: the MSDP peer nearest to the receivers, typically thesource-side RP, like RP 3. Upon receiving an SA message, the receiver-sideMSDP peer resolves the multicast source information carried in the message andjoins the SPT rooted at the source across the PIM-SM domain. When multicastdata from the multicast source arrives, the receiver-side MSDP peer forwards thedata to the receivers along the RPT.z Intermediate MSDP peer: an MSDP peer with multicast remote MSDP peers, likeRP 2. An intermediate MSDP peer forwards SA messages received from oneremote MSDP peer to other remote MSDP peers, functioning as a relay ofmulticast 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 MSDPpeers just forward received SA messages.Note:An RP is dynamically elected from C-RPs. To enhance network robustness, a PIM-SMnetwork 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-RPis always on the "MSDP interconnection map”, while loser C-RPs will assume the roleof common PIM-SM routers on the “MSDP interconnection map”.II. Implementing inter-domain multicast delivery by leveraging MSDP peersAs shown in Figure 5-2, an active source (Source) exists in the domain PIM-SM 1, andRP 1 has learned the existence of Source through multicast source registration. If RPsin PIM-SM 2 and PIM-SM 3 also wish to know the specific location of Source so thatreceiver hosts can receive multicast traffic originated from it, MSDP peeringrelationships should be established between RP 1 and RP 3 and between RP 3 and RP2 respectively.
