Re: When IGMPv3 router in EXCLUDE(X, Y) state receives TO_IN(A)

The Group-Specific query is to find out if there are any hosts which  
still have EXCLUDE state -- the Group-Specific query will lower the  
router's Group Timer to LMQT, and if no hosts respond with IS_EX  
Current-State records, the Group Record will switch to INCLUDE filter- 
mode if there are still Source Records with timers running.

On Mar 12, 2008, at 2:46 AM, Rohan Sen wrote:

> Hi,
>
> RFC 3376 Section 6.4.2 change state record handling router state  
> machine last line mentions about sending a group specific query in  
> addition to the source specific query.
> I am not very sure if I am able to understand the necessity of this  
> group specific query. Usually a TO_IN(A) message is received from a  
> host that underwent a state change from EXCLUDE(A) to INCLUDE(A)  
> which means the router already had a state of EXCLUDE(X,Y) where A  
> is a subset of Y. The router then tries to find out if there is any  
> host which still has interest in receiving traffic for the sources  
> already having source timer > 0. I do not understand what is the use  
> of sending a group specific query in this case since the group  
> specific query has a wider scoped purpose than the source specific  
> query.
>
> Could it be that since for other cases no query is sent if sources  
> to be queried is NULL set, for this case only (since TO_IN(NULL) is  
> the IGMPv3 translation for IGMPv2 Leave when older version host for  
> that group is present) a group specific query has to be sent  
> regardless of whether the to be queried source set is NULL or not.
>
> Any help on these lines would be highly appreciated.
>
> -- 
> thanks,
> Rohan Sen _______________________________________________
> magma mailing list
> [email protected]
> https://www.ietf.org/mailman/listinfo/magma