linux-kernel - Re: [PATCH net] bridge: notify user space after fdb update

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Message-ID: <20140530073224.2d0baa37@nehalam.linuxnetplumber.net>
Date:	Fri, 30 May 2014 07:32:24 -0700
From:	Stephen Hemminger <stephen@...workplumber.org>
To:	Jon Maxwell <jmaxwell37@...il.com>
Cc:	davem@...emloft.net, makita.toshiaki@....ntt.co.jp,
	vyasevic@...hat.com, bridge@...ts.linux-foundation.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	jpirko@...hat.com, jmaxwell@...hat.com
Subject: Re: [PATCH net] bridge: notify user space after fdb update

On Thu, 29 May 2014 17:27:16 +1000
Jon Maxwell <jmaxwell37@...il.com> wrote:

> There has been a number incidents recently where customers running KVM have
> reported that VM hosts on different Hypervisors are unreachable. Based on
> pcap traces we found that the bridge was broadcasting the ARP request out
> onto the network. However some NICs have an inbuilt switch which on occasions
> were broadcasting the VMs ARP request back through the physical NIC on the
> Hypervisor. This resulted in the bridge changing ports and incorrectly learning
> that the VMs mac address was external. As a result the ARP reply was directed
> back onto the external network and VM never updated it's ARP cache. This patch
> will notify the bridge command, after a fdb has been updated to identify such
> port toggling.
> 
> Signed-off-by: Jon Maxwell <jmaxwell37@...il.com>

Acked-by: Stephen Hemminger <stephen@...workplumber.org>
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