MSDP and PIM

[hotpackets]

Is PIM required between MSDP peers? I've been told that it's not but I can't get it to work in my lab. The first packet gets encapsulated in the MSDP message and makes it all the way to the destination, but subsequent packets don't go through unless I configure PIM end-to-end.

[johnd2310]

Hi,

What is your MSDP configuration?

Thanks

John

[hotpackets]

R1---R2---R3---R4

OSPF/PIM-SM between R1 and R2

OSPF/PIM-SM between R3 and R4

eBGP between R2 and R3

Full IP reachability

MSDP between R2 and R3

R2:
ip msdp peer 3.3.3.3 connect-source Loopback0
ip msdp originator-id Loopback0

R3:
ip msdp peer 2.2.2.2 connect-source Loopback0
ip msdp originator-id Loopback0

On R1, I'm listening on 224.1.1.1 and 239.1.1.1

On R4, I ping either mcast address and the first packet makes it. Packet capture shows that it's encapsulated in the MSDP message. Subsequent packets do not go through until the S,G entries timeout.

I've tried with "ip pim bsr-border" on the interfaces between R2 and R3 and it doesn't work. PIM adjacency didn't form with those commands contrary to the documentation I've read.

[johnd2310 · Accepted solution]

Hi,

If you want multicast traffic to flow from R4 to R1, then you need pim along the whole path i.e. R1-pim-R2-pim-R3-pim-R4.

MSDP is used for source discovery i.e. share SAs.

In your example R1- R2 are multicast domain1 and R3 -R4 are multicast domain2. R2 is RP for domain1 and R3 is RP for domain2. You want multicast between the two domains:

• enable pim on all interfaces in the path
• configure MSDP between R2 and R3 to share SAs from the two domains

Thanks

John

[balaji.bandi]

We would like to know more about your use case and requirement? how your underlay infrastructure connected.

and why do you do think you need MSDP ?  and provide the high level network diagram and device configuration to understand better.

here is the guidelines for MSPD deployment :

https://community.cisco.com/t5/networking-documents/how-to-configure-ip-multicast-using-msdp/ta-p/3131576

suggest good example : ( you can also do without BGP)

https://cciethebeginning.wordpress.com/2008/08/24/msdp-and-inter-domain-multicast/