Subject: igmpv3 question

From: [email-masked]
Date: Tue, 24 Apr 2001 10:49:38 -0700

Hi all,

     In IGMPV3, when a router receives an exclude mode response for a group G,
it will keep state for that group in the format of  EXCLUDE(A,B).  According to
the draft, A is the set which represents "conflicts in the desired reception
state" (section 6.2.1).  When a IS_EX(B) is received with the router in a state
of INCLUDE(A), the new router state will become EXCLUDE(A*B,B-A) (section
6.4.1). THis definition of A is not consistent with the following description
from Appendix A.3: "One of the ways to accomplish this is for routers to keep
track of all sources desired by hosts that are in INCLUDE mode even though the
router itself is in EXCLUDE mode."  If we follows the description in Appendix
A.3, then when a IS_EX(B) is received with the router in a state of INCLUDE(A),
the new router state should become EXCLUDE(A,B-A).

For example, after the following set of reports,
IS_IN({a}) from host1
IS_IN({b}) from host2
IS_EX({b,c}) from host3,
the router will have a state of EXCLUDE({b},{c}) using the rules in section
6.4.1.

But if we follows the description in Appendix A.3, then the router will have a
state of EXCLUDE({a,b},{c}).

Also the rules in section 6.4.1 seem to have the following property: the final
state in the router depends on the order of the reports it receives.  For
example, if the order of the reports in the above example is changed to
IS_IN({b}), IS_EX({b,c}), IS_IN({a}), then the state in the router will become
EXCLUDE({a,b},{c}).

Am I missing something??

Regards,
-- James Huang