From: Joseph Brunner (joe@affirmedsystems.com)
Date: Thu May 22 2008 - 18:24:18 ART
Again, only if the joins work to get the interface into the outgoing
interface list. I posted some debugs here last year for the pim joins that
occur during each kind of multicast interface operation, and regarding how
the group is operating.
I recommending testing this on NON-DYNAMIPS routers :0)
_____
From: lei tian [mailto:again.tl@gmail.com]
Sent: Thursday, May 22, 2008 5:20 PM
To: Joseph Brunner
Cc: ccie; Cisco certification
Subject: Re: no ip pim dm-fallback vs no ip pim autorp listener
So dense mode traffic will be pushed out regardless of the mode of
interfaces is operating. That is good to know.
Thanks
Lei
On Thu, May 22, 2008 at 4:35 PM, Joseph Brunner <joe@affirmedsystems.com>
wrote:
Without "no ip pim dm-fallback" implemented, what router will do with
traffic in dense mode group, I mean which interface will the traffic be sent
out?
>The ones that have received pim joins that are in the Outgoing interface
list ;)
Form my understanding, the router will check which interfaces are operated
in dense mode then the traffic will be flood to all dense mode interfaces.
If all interfaces are running sparse mode, then traffic will be sent out
nowhere.
>no. the group will simply flood and prune if you are using old old code.
Lately, we have dense mode state refresh, so rather than flooding until a
prune is heard, the router with a dense mode >group will not flood the group
if the group is not requested. Similar to sparse mode, except it is doing it
per group without an RP.
>again the interface modes decide how the router learns rp information. Not
how the multicast traffic is forwarded. I tested this in my lab last year by
running multicast traffic over a network of "sparse mode interfaces" with no
RP configured. I obviously did not remove the "ip pim dm-fallback" default
operation.
That will not make any difference after implement "no ip pim dm-fallback".
That's why I said "no ip pim dm-fallback" doesnt do anything if all
interfaces are running sparse.
Correct me If I am wrong .
>yes you are wrong the. The interfaces can do what ever they are configured
to do. the router forwards multicasts based on the properties of the groups
in the mroute table, and then looks to see if "ip pim dm-fallback" is
configured. That is why "ip pim dm-fallback" is a default command. If the RP
is lost due to interface MIS CONFIGURATION (i.e. using SPARSE with AUTO-RP
and not using IP PIM AUTORP LISTENER, ETC) the traffic can still flow in
dense mode for that group.
Just read the whole univercd explanation of the ip pim dm-fallback command a
couple of times. It will make sense to you.
Thanks,
Joe
This archive was generated by hypermail 2.1.4 : Mon Jun 02 2008 - 06:59:18 ART