Subject: RE: X in igmpv3 EXCLUDE(X,Y) ?

From: LEVIS Pierre FTRD/DMI/CAE <[email-masked]>
Date: Fri, 11 Aug 2000 09:10:30 +0200

After Isidor and Wilbert answers I'm still a little bit confused.

From Isidor I understand X is the set of sources excluded by at least one
host in EXCLUDE mode AND at least requested by one host in INCLUDE mode.
This was my first interpretation in my previous message.

From Wilbert I understand X is the set of sources requested by at least one
host in INCLUDE mode, no matter the source lists for hosts in EXCLUDE mode.
This was my second interpretation in my previous message.

Let's give an example,
Three hosts with the following states for a specific group
EXCLUDE{a,b}
INCLUDE{a}
INCLUDE{c}
Will the router state be:
EXCLUDE({a},{b}) interpretation 1 ?
or 
EXCLUDE({a,c},{b}) interpretation 2 ?
In case of 1, if host in EXCLUDE{a,b} ceases reporting, when router switches
to INCLUDE mode how will it know about source c ?

What am I missing ?

Thanks,

Pierre

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From: Isidor Kouvelas <[email-masked]>
Date: Fri, 11 Aug 2000 11:19:04 -0700

Pierre,

The list of sources X contains all the sources reported from hosts
in INCLUDE mode up to the point where an exclude report is received.
At that point, only the conflicting sources are kept. This is repeated
in each query interval.
When the last host in EXCLUDE mode leaves the group, the router sends
a group specific query. This causes the EXCLUDE group timer on the router
to be lowered. At this point all hosts in INCLUDE mode respond and update
the list X. As there are no hosts left in EXCLUDE mode, no EXCLUDE reports
are received to update the group timer. Hence the timer expires with all
the sources in INCLUDE mode listed in X. At this point list X is used as
the list of source to forward in INCLUDE mode.

thanks
Isidor