Discussion:
Linux Bridge Static FDB move
(too old to reply)
V***@dell.com
2017-10-25 16:47:18 UTC
Permalink
Hi Everyone,


Is it possible to program the FDB entry in Linux Bridge which is static, non-local and doesn't move to new interface when the same source MAC packet comes on a different interface in the same bridge ?


I tried programming the MAC as permanent that prevents the moving of MAC to a new interface in the same bridge, however it treats the MAC as local and doesn't do the forwarding ?


Thanks,

Viraj
Toshiaki Makita
2017-10-26 11:13:11 UTC
Permalink
On 2017/10/26 1:47, ***@dell.com wrote:
> Hi Everyone,
>
>
> Is it possible to program the FDB entry in Linux Bridge which is static,
> non-local and doesn't move to new interface when the same source MAC
> packet comes on a different interface in the same bridge  ?

AFAIK no.
Bridge supports static fdb entries, but br_fdb_update() updates their
dst even for static entries.

>
>
> I tried programming the MAC as permanent that prevents the moving of MAC
> to a new interface in the same bridge, however it treats the MAC as
> local and doesn't do the forwarding ?

Yes, local entries will deliver frames to the bridge device itself.

--
Toshiaki Makita
V***@dell.com
2017-10-26 17:33:49 UTC
Permalink
Thank you for the reply.

Viraj
________________________________________
From: Toshiaki Makita <***@lab.ntt.co.jp>
Sent: Thursday, October 26, 2017 4:13 AM
To: Raiyani, Viraj; ***@lists.linux-foundation.org
Subject: Re: [Bridge] Linux Bridge Static FDB move

On 2017/10/26 1:47, ***@dell.com wrote:
> Hi Everyone,
>
>
> Is it possible to program the FDB entry in Linux Bridge which is static,
> non-local and doesn't move to new interface when the same source MAC
> packet comes on a different interface in the same bridge ?

AFAIK no.
Bridge supports static fdb entries, but br_fdb_update() updates their
dst even for static entries.

>
>
> I tried programming the MAC as permanent that prevents the moving of MAC
> to a new interface in the same bridge, however it treats the MAC as
> local and doesn't do the forwarding ?

Yes, local entries will deliver frames to the bridge device itself.

--
Toshiaki Makita
Stephen Hemminger
2017-10-26 18:55:01 UTC
Permalink
If you have a moving MAC then you have a network that is flapping,
duplicate MAC, or worse a network loop. All of these are signs of a broken
L2 network. The bridge can't fix these

On Oct 26, 2017 19:33, <***@dell.com> wrote:

> Thank you for the reply.
>
> Viraj
> ________________________________________
> From: Toshiaki Makita <***@lab.ntt.co.jp>
> Sent: Thursday, October 26, 2017 4:13 AM
> To: Raiyani, Viraj; ***@lists.linux-foundation.org
> Subject: Re: [Bridge] Linux Bridge Static FDB move
>
> On 2017/10/26 1:47, ***@dell.com wrote:
> > Hi Everyone,
> >
> >
> > Is it possible to program the FDB entry in Linux Bridge which is static,
> > non-local and doesn't move to new interface when the same source MAC
> > packet comes on a different interface in the same bridge ?
>
> AFAIK no.
> Bridge supports static fdb entries, but br_fdb_update() updates their
> dst even for static entries.
>
> >
> >
> > I tried programming the MAC as permanent that prevents the moving of MAC
> > to a new interface in the same bridge, however it treats the MAC as
> > local and doesn't do the forwarding ?
>
> Yes, local entries will deliver frames to the bridge device itself.
>
> --
> Toshiaki Makita
>
>
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