Multicast-Multicast Source Discovery Protocol & Anycast

MSDP or Multicast Source Discovery Protocol is used to exchange multicast source information between RPs. A TCP connection between the RPs and used to exchange the so-called Source Active (SA) messages. Each domain usually has its own RP. To allow sources and receivers from different domains to locate each other, RPs need to exchange the information about their local active sources.

Anycast RP is a special RP redundancy scenario that allows using redundant RPs sharing the sameIP address. Here, Anycast means that groups of RPs use the same IP address used by all multicast routers in the domain to build shared trees. However, the PIM Joins are being sent to the closest RP, based on the unicast routing table.

 
R2#
interface Loopback0
 ip address 25.25.25.25 255.255.255.0
 ip pim sparse-mode
!
interface Loopback1
 ip address 200.200.200.200 255.255.255.0
!
interface FastEthernet0/0
 ip address 23.1.1.2 255.255.255.0
 ip pim sparse-mode
 duplex auto
 speed auto
!
router ospf 10
 log-adjacency-changes
 network 0.0.0.0 255.255.255.255 area 0
!
ip pim rp-candidate Loopback0
 
R5#
interface Loopback0
 ip address 25.25.25.25 255.255.255.0
 ip pim sparse-mode
!
interface FastEthernet0/0
 ip address 45.1.1.5 255.255.255.0
 ip pim sparse-mode
 duplex auto
 speed auto
!
router ospf 10
 log-adjacency-changes
 network 0.0.0.0 255.255.255.255 area 0
!
ip pim rp-candidate Loopback0




R3#
interface Loopback0
 ip address 3.3.3.3 255.255.255.0
 ip pim sparse-mode
!
interface FastEthernet0/0
 ip address 13.1.1.3 255.255.255.0
 ip pim sparse-mode
 duplex auto
 speed auto
!
interface FastEthernet0/1
 ip address 34.1.1.3 255.255.255.0
 ip pim sparse-mode
 duplex auto
 speed auto
!
interface FastEthernet1/0
 ip address 23.1.1.3 255.255.255.0
 ip pim sparse-mode
 duplex auto
 speed auto
!
router ospf 10
 log-adjacency-changes
 network 0.0.0.0 255.255.255.255 area 0
!
ip pim bsr-candidate Loopback0 0






R6(config)#int f0/0
R6(config-if)#ip igmp join-group 224.1.1.1





R2#
int lo2
ip add 22.22.22.22 255.255.255.0
!
R2(config-if)#ip msdp originator-id lo2
R2(config)#ip msdp peer 55.55.55.55 connect-source lo2
R5#
int lo2
ip add 55.55.55.55 255.255.255.0
!
R5(config-if)#ip msdp originator-id lo2
R5(config)#ip msdp peer 22.22.22.22 connect-source lo2

Multicast-Stub Multicast Routing & IGMP Helper

Stub multicast routing is useful in situations where you have small remote sites connected to a centralized WAN cloud across low-bandwidth links that use low-end routers. This forwards all IGMP messages to the central router, without processing the typical IGMP report and query messages necessary itself, to make PIM work. If both routers were to run PIM SM, R8 would have to accept RP discovery messages, build its own RP cache, and maintain states for all multicast groups joined by local receivers, thus possibly over-taxing a small router’s resources. Being a stub multicast router allows R8 to be exempted from PIM and IGMP message processing.
 
R1(config)#
interface FastEthernet0/0
 ip address 12.1.1.1 255.255.255.0
 ip pim sparse-mode
 duplex auto
 speed auto
end
R2(config)#
interface FastEthernet0/0
 ip address 12.1.1.2 255.255.255.0
 ip pim sparse-mode
 duplex auto
 speed auto
end
!
interface FastEthernet0/1
 ip address 23.1.1.2 255.255.255.0
 ip pim sparse-mode
 duplex auto
 speed auto
end
R3(config)#
interface FastEthernet0/0
 ip address 23.1.1.3 255.255.255.0
 ip pim sparse-mode
 duplex auto
 speed auto
end
interface FastEthernet0/0
 ip address 34.1.1.4 255.255.255.0
 ip pim dense-mode
 duplex auto
 speed auto
end
R5(config-if)#
interface FastEthernet0/0
 ip address 45.1.1.5 255.255.255.0
 ip pim dense-mode
 ip igmp join-group 224.1.1.1
 duplex auto
 speed auto
end

Pinging from R1
 
Applying Filter on R3
R3(config)#access-list 10 deny host 34.1.1.4
R3(config)#access-list 10 permit any
R3(config)#int f0/1
R3(config-if)#ip pim neighbor-filter 10
 
Reply on R1 Fails

Configuring igmp Helper on R4
R4#
interface FastEthernet0/1
 ip address 45.1.1.4 255.255.255.0
 ip pim dense-mode
 ip igmp helper-address 34.1.1.3
 duplex auto
 speed auto
end

We will start getting reply on R1