ip pim rp-announce-filter rp-list

[D@1984]

Im studying for my exam and trying to undrestand above command but it doesnt seem to do what it expect to .

I have 4 routers, r3 is my rp-candidate and r2 is mapping agent. loop back address of r2:2.2.2.2 and r3: 3.3.3.3, multicast group 233.1.2.3

I want to add a filter on r3 that doesnt accept 3.3.3.3 as rp-candidate for group 233.1.2.3 

so I added below on r2(mapping agent):

ip pim send-rp-discovery Loopback0 scope 255

access-list 1 deny 3.3.3.3

ip pim rp-announce-filter rp-list 1 

ip pim sent-rp-discovery loopback 0 

on my rp-candidate:

ip pim send-rp-announce Loopback0 scope 255 group-list 1
!
access-list 1 permit 233.1.2.3

but going to r4 and do show ip pim rp mappin, I still can see 3.3.3.3 as rp for group 233.1.2.3.

am I missing something here?

Thanks

[David Ruess]

Hello,

You might have the config backwards. YOu are denying the R3:3.3.3.3 which means its not checked by the FIlter list. Refer to this document:

How to Implement a Filtering Policy for Rendezvous Points - Cisco

It states

"Note: Use this command with caution. RPs that are matched by rp-list (allowed by a permit statement) have their multicast groups filtered by group-list. RPs that are denied (either by an explicit or implicit deny) are not subject to the filtering of their multicast groups and are "blindly" accepted as candidate RPs for all of their groups. In other words, only RPs that are permitted by rp-list have their multicast-groups filtered by group-list. All other RPs are accepted without examination."

Try permitting the 3.3.3.3 in the ACL and see if that works.

-David

[D@1984]

Sorry what I meant was permit 3.3.3.3. It still doesn’t work with 3.3.3.3.

I can still see the RP despite the fact that I filtered it.

[MHM Cisco World]

if the R4 recieve any discover from 3.3.3.3 then it will use it no use path via 2.2.2.2 to 3.3.3.3

MHM