IGMP Unsolicited Report Interval too long for IGMPv3?

[William Manley]

If an IGMP join packet is lost you will not receive data sent to the 
multicast group so if no data arrives from that multicast group in a 
period of time after the IGMP join a second IGMP join will be sent.  The 
delay between joins is the "IGMP Unsolicited Report Interval".

In the kernel this seems to be hard coded to be chosen randomly between 
0-10s.  In our use-case (IPTV) this is too long as it can cause channel 
change to be slow in the presence of packet loss.

I would guess that this 10s has come from IGMPv2 RFC2236, which was 
reduced to 1s in IGMPv3 RFC3376.

There was a thread about this on linux-rdma in 2010 in the context of IP 
over Infiniband but it seems no patches got applied as a result of the 
discussion:

http://www.mail-archive.com/linux-rdma@xxxxxxxxxxxxxxx/msg05740.html

Would the right patch reducing the unsolicited report interval for 
IGMPv3 be acceptable now?

Thanks

Will


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/