From: bhescock (bhescock@cisco.com)
Date: Thu Jun 19 2003 - 14:10:52 GMT-3
Tim,
Hi, the behavior for this changed about three years ago, per one of the Cisco Multicast Development Engineers,
which is why there may be some confusion. I had come across this inconsistency in some documentation on CCO about a
year ago and had contacted Development to ask them which is correct. The current and correct behavior is you must
specify who the rp is even on the rp itself and I requested the documentation be updated.. Please let me know if you
see any 12.x documentation on CCO that indicates otherwise, either through the text or through ommission in a
configuration. Thanks,
Brian
"Snow, Tim" wrote:
> Looks like the original didn't go through?
>
> Hello again... I have a question regarding PIM sparse-mode RP and
> whether to tell the RP that
> it is the RP. There seems to be some discrepancy with multiple cisco
> press books. See below.
>
> Per Jeff Doyle Vol II (pg 544, 1st paragraph, line 9) " The reason for
> this statement on
> this router, of course, is so that the router knows that is is the RP."
>
> Contradicting that is Beau Williamson, Multicast (Pg 343, Note section)
> "When the router,
> whose address is in this field receives the (*,G) Join message, it sees
> its own address
> in this field and assumes that i must be the RP for the group. Therefor
> a router always
> assumes the duties of the RP for a group and time it receives a an
> incoming (*,G) join
> that contains the address of one of it's multicast-enabled interfaces in
> this field"
>
> *Feb 28 22:30:41: PIM: Received v2 Join/Prune on Serial0.95 from
> 10.2.3.5, to us
> *Feb 28 22:30:41: PIM: Join-list: (*, 228.13.20.216) RP 10.224.1.1
> *Feb 28 22:30:41: PIM: (*, 228.13.20.216) Join from 10.2.3.5 for invalid
> RP 10.224.1.1
>
> r9(config)#access-list 9 deny 224.0.1.39
> r9(config)#access-list 9 deny 224.0.1.40
> r9(config)#access-list 9 permit any
> r9(config)#ip pim rp-address 10.224.1.1 9
>
> *Feb 28 22:32:40: PIM: Received v2 Join/Prune on Serial0.95 from
> 10.2.3.5, to us
> *Feb 28 22:32:40: PIM: Join-list: (*, 228.13.20.216) RP 10.224.1.1
> *Feb 28 22:32:40: MRT: Create (*, 228.13.20.216), RPF Null, PC 0x353148E
>
> *Feb 28 22:32:40: PIM: Check RP 10.224.1.1 into the (*, 228.13.20.216)
> entry, RPT-bit
> set, WC-bit set, S-bit set
> *Feb 28 22:32:40: MRT: Add/Update Serial0.95/224.0.0.2 to the olist of
> (*, 228.13.20.
> 216), Forward state
> *Feb 28 22:32:40: PIM: Add Serial0.95/10.2.3.5 to (*, 228.13.20.216),
> Forward state
>
> As you can see above, it only worked when I told the RP about the RP
> (that is, itself)
> I did try turning on "ip pim sparse" due to Williamson saying "of one of
> it's multicast
> enabled interfaces" but that didn't work. I also tried configuring a
> "ip pim accept-rp"
> permitting everything but that didn't work.
>
> Can anyone answer this for me?
>
> Thanks.
>
> TIm
>
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