MSDP (Multicast Source Discovery Protocol) has been developed to exchange information about sources of multicast traffic between multiple BGP Domain.
It can also be used as a key protocol allowing us to have two or more RPs to share the load and provide redundancy in case of RP failure.
Key Concept
- Two or more RPs are configured with the same Anycast loopback (same address & mask);
- Anycast RP loopback address should be configured with a /32 subnet;
- Two or more RPs are configured with a second unique loopback for MSDP peering and exchange information about sources;
- Loopback interfaces should all be reachable via unicast routing protocol (or static routing);
- Anycast RP is based on unicast routing protocol. Source traffic will be routed to the closest RP
- BSR and Auto-RP can be used on top of Anycast RP for RP distribution
## Switch1 ## int lo0 description Anycast RP IP ip address 10.10.10.10 255.255.255.255 ip pim sparse-mode int lo1 description MSDP Peering ip address 1.1.1.1 255.255.255.255 router ospf 1 network 1.1.1.1 0.0.0.0 area 0 network 10.10.10.10 0.0.0.0 area 0 router-id 172.16.10.1 ip msdp peer 2.2.2.2 connect-source lo1 ip mspd originator-id lo1 ip pim rp-address 10.10.10.10 ## Switch2 ## int lo0 description Anycast RP IP ip address 10.10.10.10 255.255.255.255 ip pim sparse-mode int lo1 description MSDP Peering ip address 2.2.2.2 255.255.255.255 router ospf 1 network 2.2.2.2 0.0.0.0 area 0 network 10.10.10.10 0.0.0.0 area 0 router-id 172.16.10.2 ip msdp peer 1.1.1.1 connect-source lo1 ip mspd originator-id lo1 ip pim rp-address 10.10.10.10
Notes:
- Anycast RP loopback should be configured to participate into PIM
- Do not forget to set the MSDP originator-id, otherwise, the SAs won’t be shared between RPs
- Be sure to configure manually router-id for the unicast routing protocol, this avoid the Anycast RP address to be elected as router-id if the device reboot
- PIM rp-address must be configured on all device taking part in the multicast routing like with static RP configuration
- We can check MSDP peering using the show ip msdp summary. State should be Up
- Default MSDP keepalive timer is set to 60 seconds.