netdev - Re: [Bridge] [PATCH RFC 0/7] Non-promisc bidge ports support

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Date:	Thu, 27 Feb 2014 08:54:16 +0000
From:	Amidu Sila <amidu@...itel.com>
To:	vyasevic@...hat.com, Jamal Hadi Salim <jhs@...atatu.com>,
	netdev@...r.kernel.org
CC:	john.r.fastabend@...el.com, shemminger@...tta.com,
	bridge@...ts.linux-foundation.org, mst@...hat.com
Subject: Re: [Bridge] [PATCH RFC 0/7] Non-promisc bidge ports support

Please, unsubscribe me.
Regards
Amidu Sila

On 2/27/14, 03:37 AM, Vlad Yasevich wrote:
> On 02/26/2014 06:59 PM, Jamal Hadi Salim wrote:
>> On 02/26/14 10:18, Vlad Yasevich wrote:
>>> This patch series is a complete re-design and re-implementation of
>>> prior attempts to support non-promiscuous bridge ports.
>>>
>>> The basic design is as follows.  The bridge keeps track of
>>> all the ports that flood packets to unknown destinations.  If
>>> the flooding is disabled on the port, to get traffic to flow
>>> through, user/management would need to add an fdb describing
>>> such traffic.  When such fdb is added, we save the address
>>> to bridge private hardware address list.
>> Entering the addresses in the uc list on other bridgeports seems
>> reasonable for the scenario described.
>> But would it _also_ need to be added to the fdb of the bridge?
>> i.e how does the bridge (if the packet was to be handed to it)
>> know where to forward?
> The fdb described here is actually added to the bridge.  In the case
> when we are turning promiscuous mode off on a port, we program the
> address from the fdb down to the port uc list as well.  This allows
> the bridge to continue receiving traffic destined for this address even
> though the port is not in promiscuous mode.
>
>> BTW: on the comment that flooding off implies learning off: I would like
>> to be able to turn off flooding on a specific bridge port but
>> still want to learn from it. I dont think those two are mutually
>> exclusive.
> No they are not, but it does lead to some very interesting traffic
> hang-ups that I've experienced first hand.  Everything works great
> in the beginning.  However, if you go idle for a long enough period
> that the fdb times out, re-establishing the connection take a rather
> long time due to unicast ARPs being dropped by the bridge.  You end
> up waiting until arp fails and switches to broadcast to restore the
> connection.  So, this mode isn't really recommended.  Nothing currently
> forbids it however.
>
> -vlad
>> cheers,
>> jamal

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