From: gladston@br.ibm.com
Date: Tue Aug 30 2005 - 19:30:30 GMT-3
Hi Simon,
Thanks,
I agree, but I think that should be added:
the mode is determined by whether there is an RP for the group "when the
interface is configure for ip pim sparse-dense-mode" and not whether the
interface is running in a particular mode.
That is not valid for ip pim sparse-mode or ip pim dense-mode on the
interface.
What do you think?
Cordially,
------------------------------------------------------------------
Gladston
"simon hart" <simon@harttel.com>
30/08/2005 16:37
To
Alaerte Gladston Vidali/Brazil/IBM@IBMBR, <ccielab@groupstudy.com>
cc
"ccie2be" <ccie2be@nyc.rr.com>
Subject
RE: Sparse-Mode with no RP
Hi Gladston,
If your interfaces are configured as sparse-mode then no mcast traffic
will
be forwarded because there is no RP, and thus no *,G entry in the mroute
table. Therefore the interface does not know where to send the traffic.
If your interfaces are configured as dense-mode, then mcast traffic will
be
forwarded out of all dense-mode interfaces until it recieves a prune from
its PIM neighbor, the router will build S,G entries based upon this
behaviour.
If you interfaces are configured as sparse-dense-mode, then the router
will
forward the traffic in one of two fashions,
A) if there is an RP configured then out of the interface that is dictated
by the *,G entry (i.e. the 'nearest' interface to the RP)
B) if there is no RP configured, then out of every interface, and then
wait
for the prunes ( building S,G entries)
So I guess the statement
============
The mode of the interface DOES NOT determine whether a mcast group runs in
sparse or dense mode.
============
means that the mode is determined by whether there is an RP for the group,
and not whether the interface is running in a particular mode,
HTH
Simon
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
gladston@br.ibm.com
Sent: 30 August 2005 16:35
To: ccielab@groupstudy.com
Cc: ccie2be
Subject: Sparse-Mode with no RP
Trying to check the following discussion:
http://www.groupstudy.com/archives/ccielab/200407/msg01404.html
specifically the statement:
============
The mode of the interface DOES NOT determine whether a mcast group runs in
sparse or dense mode.
============
I got this:
If a interface is configured as sparse-mode, the router does not forward
traffic out the interface if there is no RP. That was revealed by debug,
and the tests are at the end of this email.
I am concerned with the following: is it possible to forward multicast if
there is no RP and the interfaces are configured for sparse-mode?
Tests:
When the interfaces are configured for sparse-dense-mode, R2 forwards the
multicast traffic to R6 and R8 (and receives the prune from remote
router):
Aug 30 11:42:41: PIM(0): Received v2 Join/Prune on Serial0/0.28 from
148.5.28.8, to us
Aug 30 11:42:41: PIM(0): Prune-list: (148.5.235.5/32, 239.200.1.1)
Aug 30 11:42:41: PIM(0): Prune Serial0/0.28/239.200.1.1 from
(148.5.235.5/32, 239.200.1.1)
Aug 30 11:42:41: PIM(0): Received v2 Assert on Serial0/0.26 from
148.5.126.6
When the interface 0/0.28 (lead to R8) is configured for sparse-mode, the
router does not forward multicast traffic to that router:
no result from debug for R8
Version is 12.2T. Have you seen different results?
This archive was generated by hypermail 2.1.4 : Sun Sep 04 2005 - 17:01:20 GMT-3