RE: ip igmp join-group 3750

From: Joseph Brunner (joe@affirmedsystems.com)
Date: Fri Mar 21 2008 - 00:30:57 ART


This is always the case;

Isn't responding to your pings multicast routing????

Doesn't processing the group with the join-group command require igmp be
running (and how do we enable igmp??? By turning on pim!!!)

-joe

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
lhall@setnine.com
Sent: Thursday, March 20, 2008 7:00 PM
To: ccielab@groupstudy.com
Subject: ip igmp join-group 3750

I'm doing some labs using 3750's, for a reason I cannot figure out,
these will not respond to pings if on physical port (no switchport)
you configure `ip igmp join-group X` _unless_ you also enable PIM on the
on the interface and enable `ip multicast-routing distributed`.
Does anyone know why this is?

Wont work:

interface FastEthernet1/0/3
 no switchport
 ip address 12.2.40.5 255.255.255.0
 ip igmp join-group 225.1.1.1
 no ip mroute-cache

Will work:

ip multicast-routing distributed
!
interface FastEthernet1/0/3
 no switchport
 ip pim dense-mode (or sparse etc)
 ip address 12.2.40.5 255.255.255.0
 ip igmp join-group 225.1.1.1
 no ip mroute-cache

They are all WS-C3750-24TS running 12.2(25)SEE C3750-ADVIPSERVICESK.

Luca



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