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Date:      Wed, 13 Feb 2013 10:28:47 -0600
From:      Kevin Day <kevin@your.org>
To:        Josef Pojsl <jp@tns.cz>
Cc:        freebsd-net@freebsd.org
Subject:   Re: lacp on lagg interface: same speed, different media
Message-ID:  <0C4010B3-C317-4510-B277-9BD768DF5344@your.org>
In-Reply-To: <511AB7A0.6020506@tns.cz>
References:  <511AB7A0.6020506@tns.cz>

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On Feb 12, 2013, at 3:44 PM, Josef Pojsl <jp@tns.cz> wrote:

> Hello list,
>=20
> on a FreeBSD 8.3-RELEASE-p3, I have come across a problem with lacp
> protocol on a lagg interface. I have aggregated two interfaces with =
the
> same speed but slightly different type of media (namely 10Gbase-SR and
> 10Gbase-LR). There is a Cisco switch on the other side.
>=20
> LACP won't work as my FreeBSD box computes the actor key differently =
for
> the two interfaces. This is weird as LACP inists on the same speed but
> not on the same exact type of media. Cisco has no problem having one
> aggregated interface Short and the other Long Range.
>=20
> Below, I have attached a tiny patch that changes the actor key
> computation so that only speed is important, not the exact media type.
> This patch works for me, LACP is ok with the Cisco box on the other
> side. Please could someone competent look at the patch and test or
> evaluate if it can be included in the code base. Thank you.
>=20

I believe this is intentional behavior. My understanding is that 802.3ad =
requires that the media types be *identical*. The logic is that if you =
advertise multiple ports under the same key, any port on one side can be =
physically connected to any port on the other side.=20

I'm not sure how important strict compliance v.s. making it actually =
work is here, and I tend to agree that this is overly picky, and I can't =
think of anything except seriously contrived instances where this would =
matter.  I also think most vendors have agreed with this and have =
stopped caring about it. (sometimes requiring a knob to be changed)








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