Re: [PATCH 1/2] IGMP snooping: set mrouters_only flag for IPv4 traffic properly

David Miller [off-list ref] wrote:

From: Fernando Luis Vázquez Cao <redacted>
Date: Tue, 14 Jun 2011 10:04:43 +0900

quoted

Upon reception of a IGMP/IGMPv2 membership report the kernel sets the
mrouters_only flag in a skb that may be a clone of the original skb, which
means that sometimes the bridge loses track of membership report packets (cb
buffers are tied to a specific skb and not shared) and it ends up forwading
join requests to the bridge interface.

This can cause unexpected membership timeouts and intermitent/permanent loss
of connectivity as described in RFC 4541 [2.1.1. IGMP Forwarding Rules]:

    A snooping switch should forward IGMP Membership Reports only to
    those ports where multicast routers are attached.
    [...]
    Sending membership reports to other hosts can result, for IGMPv1
    and IGMPv2, in unintentionally preventing a host from joining a
    specific multicast group.


Signed-off-by: Fernando Luis Vazquez Cao <redacted>
Tested-by: Hayato Kakuta <redacted>

Applied.

Thank you David.

By the way, What kernel version(s) are you targeting for these two
patches. It would be great if we could get them upstream before 3.0
comes out. Without this fix the IGMP snooping code is simply unusable in
certain configurations.

- Fernando