lacp on lagg interface: same speed, different media

[Kevin Day]

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

> Hello list,
> 
> 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.
> 
> 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.
> 
> 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.
> 

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. 

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)