multicast querier

I have been getting different answers from different cisco books and other documents

In the querier election is it the higer or lower ip address that becomes the querier?

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Comments

nicklauscombs

anyone?

jezg76

My notes for the BSCI read like this:

DR - highest IP, used in IGMPv1 to send Membership Queries
Designated Querier - lowest IP, used in IGMPv2 to send Membership Queries
Forwarder - highest IP if AD/metric equal, sends multicast traffic onto segment

mikearama

I believe it's always HIGHEST IP.

The Authorized Self-Study Guide BSCI by Teare and Paquet, on page 604, under IGMPv2, states:

"When there are two IGMP routers on the same segment, the router with the highest IP address is the designated querier."

What's the source of the information suggesting otherwise?

nicklauscombs

CCIE Routing Switching Exam Guide by Odom states in IGMPV2 and V3 the router with the LOWEST ip address is elected the Querier

and i didn't see anything in the errata for either books...

thus the confusion begins...

mikearama

http://www.****.com/forum/lofiversion/index.php?t93933.html

Looks like this topic has been confusing future-NP's for a while.

The RFC, though, clearly states that in the case of multiple queriers, the one with the lower IP gets the role, and the other becomes a non-querier.

http://www.faqs.org/rfcs/rfc2236.html

Even discussed here, not that long ago:

http://www.techexams.net/forums/viewtopic.php?p=176322

So I'd stick with your CCIE sources... they seem to have it right.

Mike

nicklauscombs

sounds good thanks!

ccnpninja

Another major difference between IGMPv1 and v2 is that there is a onestep
way to make a certain IGMPv2 router become the Querier, and that's
to make sure it has the lowest IP address on the shared segment.

Taken from Chris Bryant BSCI book, for you