Subject: IGMPv2 and IGMPv1 Routers on the same segment.

From: Muruhari Amarnath <[email-masked]>
Date: Mon, 13 Dec 1999 14:48:00 -0800

Hi,

Is there any way of dynamically determining whether IGMPv1 and IGMPv2
routers are present on the same network segment.

I have a situation where I have both IGMPv1 and IGMPv2 Router are present on
the same segment.

Both Routers becomes Queriers on that network segment. 

If required more details, I can provide the configuration/information.

Thanks in advance, 

Amarnath
Pluris, Inc.

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From: Bill Fenner <[email-masked]>
Date: Mon, 13 Dec 1999 17:55:01 -0800

RFC2236 section 4 addresses this; if an IGMPv2 router is placed on a
subnet with IGMPv1 routers then the IGMPv2 router must be configured to
use IGMPv1.  The fact that IGMPv1 did not specify a querier election
algorithm means that IGMPv2 routers configured to speak IGMPv1 might
not be using the same querier election algorithm, which leads to
multiple Queriers.

The solution to multiple Queriers is either to upgrade the IGMPv1 router
or get the IGMPv2 router vendor to implement a configurable querier
election protocol when in IGMPv1 mode.  (Or live with it - it only doubles
the IGMP protocol overhead and shouldn't cause any other negative effects)

  Bill