AUTORP PIM: distributing multicast groups between multiple RPs

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Aug 1st, 2003
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I've seen the cisco doc about how to configure multiple RPs with AUTORP and to have a different range of multicast groups assigned to each RP, but i don't understand totally how the acl you apply to do so works. This is, to do so you use in the config of the C-RP some like this:

ip pim send-rp-announce Loopback0 scope 15 group-list 33

Where "33" is an ACL, that in my case is:

access-list 33 permit 228.0.0.0 10.255.255.255

Whit this config, i though that this router will be the RP only for the multicast groups that have a first octec like:

228

230

236

238

This is, i though the acl forces the exact match in the bits that you have put as "0" in the wildcard mask.

However, i'm seing that a multicast group like 229.6.6.6 is accepted too by this c-rp, and in deed the router is elected as RP for this group.

Please, can anyone explain how this acl is interpreted for the system?

REGARDS

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owillins Thu, 08/07/2003 - 12:25
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access-list 5 permit 224.0.0.0 15.255.255.255

ip pim send-rp-announce scope 15 group-list 5

would denote access-lists for class-D space. (224-239)

from your config 229 would be allowed since the range defined bu the ACL is 228-238 that includes 229 also.


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