From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Thu Mar 22 2007 - 21:01:54 ART
I've seen bugs in the older 12.1 3550 code in which it would not
forward multicast at layer 2 while it was routing IP without enabling
PIM. This is however not the normal behavior. Assuming that IGMP
snooping is enabled and the servers are sending IGMP joins for the group
they're heartbeating to you shouldn't have a problem. If it doesn't
work for some reason you can always put a static entry in the CAM table
for that multicast MAC to go out both ports. Like I said though it
should work as you described without any additional configuration or
layer 3 intervention.
HTH,
Brian McGahan, CCIE #8593 (R&S/SP)
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987 x 705
Outside US: 775-826-4344 x 705
24/7 Support: http://forum.internetworkexpert.com
Live Chat: http://www.internetworkexpert.com/chat/
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Peyton Schouest
Sent: Thursday, March 22, 2007 12:45 PM
To: ccielab@groupstudy.com
Subject: multicast.
I have come across a situation at work wondering if any of the more
knowledgable people out there could shed some light on this for me.
From my understanding if a switch does not know what ports a multicast
packet should go to it will broadcast it by default. The issue at work
is we
have two servers that basically have a heart beat or stay alive
communiction
between them and they use a multicast address. Both servers are on the
same
vlan same switch. The heart beat is set for once every 10 seconds the
two
servers will send out one multicast packet. This all seems pretty
straight
forward except that I have a sys admin telling me it will not work
because
cisco switches will only forward 3 packets and then it quits forwarding
multicast by default which I have never in my life heard of. Because of
this
"feature" he states that we must enable multicast routing and pim on the
vlan interface for the servers heart beat to work. I have never heard of
any
so called feature or bug before concerning a cisco switch. Has anyone
dealt
with something like this before or able to stregnthen an argument from
either side? Thank you for your help before hand.
Peyton
This archive was generated by hypermail 2.1.4 : Sun Apr 01 2007 - 06:35:52 ART