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Community Member

2 basic questions on multicasting

Dear Friends,

A few doubts on implementing multicasting on 6500 switches:

1. Should i configure ip pim auto rp listener on the rp itself?

2. Should i configure ip pim sparse-mode even on the interface connecting to the source of the multicast?

Thanks a lot

Gautam

4 ACCEPTED SOLUTIONS

Accepted Solutions
Hall of Fame Super Bronze

Re: 2 basic questions on multicasting

1. Should i configure ip pim auto rp listener on the rp itself?

No, the auto-rp listener is only needed on non-RP mcast routers to find the existence of an auto-rp.

2. Should i configure ip pim sparse-mode even on the interface connecting to the source of the multicast?

If it's a Layer3 interface, yes. If it's a L2 interface (access vlan or trunk port) no.

Regards,

Edison

Silver

Re: 2 basic questions on multicasting

The auto-rp listener is used to overcome the need to configured a
sparse-dense-mode, when you actually only need sparse mode, but still to use
auto-RP. The candidate-RP and mapping agent using multicast address
224.0.0.39 & 224.0.0.40 must communicate using dense-mode ie the path from
the candidate-RP to the mapping agent must be sparse-dense-mode or
dense-mode, for the mapping agent to hear the announcements from the
candidate-RP.

When you then configure auto-rp listener, you are essentially telling the
multicast process to use dense-mode communication for multicast address
224.0.0.39 & 224.0.0.40 and sparse-mode for other multicast addresses, with
that you can use sparse mode throughout your network and candidate-RP and
mapping agent will still be able to talk to each other.

regards
Shivlu Jain

Hall of Fame Super Bronze

Re: 2 basic questions on multicasting

For RP redundancy, you need to implement Anycast RP

The following white paper gives you a high level overview of its implementation:

http://www.cisco.com/en/US/docs/ios/solutions_docs/ip_multicast/White_papers/anycast.html

Regards,

Edison

Hall of Fame Super Bronze

Re: 2 basic questions on multicasting

Access switches do not need to be modified.

Regards,

Edison

8 REPLIES
Hall of Fame Super Bronze

Re: 2 basic questions on multicasting

1. Should i configure ip pim auto rp listener on the rp itself?

No, the auto-rp listener is only needed on non-RP mcast routers to find the existence of an auto-rp.

2. Should i configure ip pim sparse-mode even on the interface connecting to the source of the multicast?

If it's a Layer3 interface, yes. If it's a L2 interface (access vlan or trunk port) no.

Regards,

Edison

Community Member

Re: 2 basic questions on multicasting

Thanks a lot Edison. I am also looking at redundancy

for RP for the same multicast group.

Do you have any link that i can read through to have a redundant RP.

Basically, i am configuring core 1 as RP and i want to have core 2 as redundant RP.

Thanks a lot

Gautam

Silver

Re: 2 basic questions on multicasting

Silver

Re: 2 basic questions on multicasting

The auto-rp listener is used to overcome the need to configured a
sparse-dense-mode, when you actually only need sparse mode, but still to use
auto-RP. The candidate-RP and mapping agent using multicast address
224.0.0.39 & 224.0.0.40 must communicate using dense-mode ie the path from
the candidate-RP to the mapping agent must be sparse-dense-mode or
dense-mode, for the mapping agent to hear the announcements from the
candidate-RP.

When you then configure auto-rp listener, you are essentially telling the
multicast process to use dense-mode communication for multicast address
224.0.0.39 & 224.0.0.40 and sparse-mode for other multicast addresses, with
that you can use sparse mode throughout your network and candidate-RP and
mapping agent will still be able to talk to each other.

regards
Shivlu Jain

Hall of Fame Super Bronze

Re: 2 basic questions on multicasting

For RP redundancy, you need to implement Anycast RP

The following white paper gives you a high level overview of its implementation:

http://www.cisco.com/en/US/docs/ios/solutions_docs/ip_multicast/White_papers/anycast.html

Regards,

Edison

Community Member

Re: 2 basic questions on multicasting

Thanks a lot.

I believe there are no changes on the access switch as the access switches are 3750 and when i ran sh ip igmp snooping, it mentioned that IGMP snooping was already enabled.

Can you confirm if access switches dont need any other config

Thanks a lot

Gautam

Hall of Fame Super Bronze

Re: 2 basic questions on multicasting

Access switches do not need to be modified.

Regards,

Edison

Hall of Fame Super Bronze

Re: 2 basic questions on multicasting

For RP redundancy, you need to  implement Anycast RP

The following white paper gives you a high level overview  of its implementation:

http://www.cisco.com/en/US/docs/ios/solutions_docs/ip_multicast/White_papers/anycast.html

Regards,

Edison

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