link aggregation - bundling 2 lagg interfaces together

Damien Fleuriot ml at
Fri Feb 4 14:41:33 UTC 2011

On 2/4/11 2:51 PM, Nikos Vassiliadis wrote:
> On 2/4/2011 2:35 PM, Damien Fleuriot wrote:
>> Even if I can't concatenate my 2 lagg interfaces into a failover one
>> over the 2 switches, the new setup will still be an improvement.
> Did you consider using STP? Are these switches RSTP capable?

The switches are running STP in pvst mode, and the basic setup of 2
interfaces in failover mode works fine for every server.

What I needed here was a bit more complex though :/

> You could create a low priority bridge acting as leaf node in the STP
> domain. This will provide redundancy between different ethernet switches,
> I just don't know if RSTP converges fast enough for your needs. Just be
> a bit careful selecting the bridge's priority. A priority of 61440 will
> be probably fine.

Since I joined my company I changed every switchport to have root guard
and bpduguard.
They shall not pass ;)

> I am *almost* sure, that if_bridge works over if_laggs, perhaps you could
> combine the two.

Your idea has merit but I'd rather the BSD box not pretend it's a layer
2 device, if that was what you were suggesting.

I think I'll just settle for 2 LACP interfaces, one on switch A for the
WAN link, one on switch B for the 2 internal VLANS :/

More information about the freebsd-stable mailing list