All things related to multicast

[John Zwiebel <>]

On Tuesday, November 5, 2002, at 06:08 PM, Tom Pusateri wrote:

> I can't really think of any problems a "rogue querier" can cause.
> All IGMP routers listen to membership reports and time groups out
> independently.

How about the draft "confusion" WRT the querier version?

True that the version used on a subnet has to be administratively
configured, but it is also true that the draft says queriers
-MUST- revert to the lowest common denominator (ie, if they hear
a v2 revert to v2) and those queries -MUST- be truncated to
8 bytes.

The result is that if you have misconfigured one router on the
subnet to be v2, the querier will become v2.  There's no way of
getting out of this unless you turn off all queriers and start
with a "clean" subnet.

FWIW: IMHO a v3 capable router should continue to send the
v3 query which v2 hosts shouldn't have trouble with because they
should be able to ignore the extra octets.  This way there is
a chance of getting back to v3 without having to turn everything
off.