Re: [Xen-devel] Why is STP turned off?

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 1/5/08 21:29, "Caitlin Bestler" <Caitlin.Bestler@xxxxxxxxxxxx> wrote:

>> All bridge interfaces but the external interface are guest vif's which
>> are
>> typically not hiding bridges. This simple topology does not require
>> STP.
>> 
>>  -- Keir
> 
> The guest vifs are indeed very unlikely to be acting as bridges.
> And any switch that only has a single uplink and N internal links
> (none of which lead to a Bridge) can indeed decide not be an 802.1
> Bridge and therefore not run spanning tree.
> 
> But if Xen is not running spanning tree and one of the Guest VIFs
> *does* run spanning tree the results can be quite messy. An explicit
> warning on this might make sense.

Actually I can't remember why we originally turned off STP. It may have been
because it took longer for the bridge to 'settle' when new vifs came online.
On the other hand I may simply have turned off STP along with other
parameters (hello/learning latencies) as part of a blanket effort to make
the bridge dumb but efficient. If others have had good experiences with STP
enabled we could consider re-enabling it in the default bridge
configuration.

 -- Keir



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