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Message-Id: <20110616.231447.1625738654020726451.davem@davemloft.net>
Date: Thu, 16 Jun 2011 23:14:47 -0400 (EDT)
From: David Miller <davem@...emloft.net>
To: fernando@....ntt.co.jp
Cc: herbert@...dor.hengli.com.au, shemminger@...tta.com,
netdev@...r.kernel.org, kakuta.hayato@....ntt.co.jp
Subject: Re: [PATCH 1/2] IGMP snooping: set mrouters_only flag for IPv4
traffic properly
From: Fernando Luis Vázquez Cao <fernando@....ntt.co.jp>
Date: Tue, 14 Jun 2011 10:04:43 +0900
> 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 <fernando@....ntt.co.jp>
> Tested-by: Hayato Kakuta <kakuta.hayato@....ntt.co.jp>
Applied.
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