netdev - Re: [PATCH net-next v2] bridge: vlan: allow to suppress local mac install for all vlans

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Message-Id: <B58362A0-3860-42AB-A13A-8158891EC956@cumulusnetworks.com>
Date:	Tue, 25 Aug 2015 22:42:49 -0700
From:	Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:	Stephen Hemminger <stephen@...workplumber.org>
Cc:	netdev@...r.kernel.org, vyasevic@...hat.com,
	toshiaki.makita1@...il.com, bridge@...ts.linux-foundation.org,
	wkok@...ulusnetworks.com, davem@...emloft.net
Subject: Re: [PATCH net-next v2] bridge: vlan: allow to suppress local mac install for all vlans


> On Aug 25, 2015, at 5:56 PM, Stephen Hemminger <stephen@...workplumber.org> wrote:
> 
> On Tue, 25 Aug 2015 17:34:55 -0700
> Nikolay Aleksandrov <razor@...ckwall.org> wrote:
> 
>> From: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
>> 
>> This patch adds a new knob that, when enabled, allows to suppress the
>> installation of local fdb entries in newly created vlans. This could
>> pose a big scalability issue if we have a large number of ports and a
>> large number of vlans, e.g. in a 48 port device with 2000 vlans these
>> entries easily go up to 96000.
>> Note that packets for these macs are still received properly because they
>> are added in vlan 0 as "own" macs and referenced when fdb lookup by vlan
>> results in a miss.
>> Also note that vlan membership of ingress port and the bridge device
>> as egress are still being correctly enforced.
>> 
>> The default (0/off) is keeping the current behaviour.
>> 
>> Based on a patch by Wilson Kok (wkok@...ulusnetworks.com).
> 
> 
> This is getting messy, but then again the bridge seems to have become
> a ghetto for a long time. I would rather see the lookup code fixed so
> that the fdb was correct.

What do you mean by it is getting messy ? The entries (normally) are being added to each
vlan so there’s not much in terms of lookup that you can fix except making the table bigger/better
but that will be only a temporary win. If you elaborate on what you mean by fdb code being fixed
I could spend time and work on fixing it. If it is resizing the table so it can handle 96k entries and
probably using the rhashtable, that is what I have in mind too.
I still think that it would be nice to have the option to avoid adding the 96k entries in the first place
and that space could be better utilized by real ones, which this option does.

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