From: Chris Lewis (chrlewiscsco@yahoo.com)
Date: Fri Nov 18 2005 - 23:37:43 GMT-3
Dick,
The first answer supplied is the only one :)
it has nothing to do with auto-rp or BSR being used to define the RP. The .40 group is there because all Cisco routers will create an IGMP join for that group when you enable PIM on the interface. Period, end of story, that is the way the engineers wrote the code. It is programmed to do this as all Cisco routers are host receivers for that group.
It is an error in reasoning to think that it is not meant to be there, when in fact it is.
Cheers
Chris
Dick Crittenden <dickcrittenden@hotmail.com> wrote:
Thank you for the quick response Chris, but I am looking at a slightly
different situation. There are two ways to configure an rp automatically.
One is Cisco' autorp and another is standards base BSR. When using Cisco's
autorp the rp candidate communicates with the mapping agent via 224.0.1.39
and the mapping agent communicates with all other multicast routers via
224.0.1.40. When using the standards based BSR addresses 224.0.1.39 and
224.0.1.40 are not used. Instead Bsr uses the pimv2 message to communicate
this same information. what is confusing me is the 224.0.1.39 address does
not appear in the ip mrouting table, but the address 224.0.1.40 still does.
I can not figure out why this is so as it is not supposed to be there. Any
suggestions on my understanding would be greatly appreciated.
TIA
Dick
----- Original Message -----
From: "Chris Lewis"
To: "Dick Crittenden" ; "Cisco certification"
Sent: Friday, November 18, 2005 3:19 PM
Subject: Re: pimv2 standards based approach
> enabling pim on an interface generates an IGMP join for that group, it
> does not matter whether you use sparse or dense mode.
>
> Chris
>
> Dick Crittenden wrote:
> Hi all, have noticed when configuring BSR multicast that the reserved
> multicast address 224.0.1.40 is still in the mrouting table. I was under
> the impression that with BSR the reserved addresses 224.0.1.39 and
> 224.0.1.40 were not used and that these address were replaced by
> leveraging the pimv2 messages.
> If anyone would be kind enough to clear this up for me I would appreciate
> it.
>
> TIA
> Dick
>
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