[j-nsp] Network, trouble after customer created a loop *inside* a VM host

[Jeff Meyers]

Hi Patrick,

> The problem is that any broadcast packets across the loop get amplified
> pretty quickly and this propagates across the entire broadcast domain
> (all related switches that have trunks containing affected vlans for
> transit).

of course, I always forget the 3rd party broadcasts when talking about 
loops.

> For the procurve I think they call the feature "flow control"
>
> so ...
>
> 	conf t
> 	fault-finder broadcast-storm
> 	interface x flow-control

I'm not sure if flow-control helps here. For my understanding, it only 
sends out pause frames and helps to make sure that one server does not 
fully utilize the uplink - but probably only if the other side has 
flow-control enabled as well.

> Should do it. Ideally I'd turn that on all ports. Note that these are
> the defaults (or at least should be). The only other way to reduce the
> effects of this is to reduce your broadcast domain (read: ports affected
> by amplified looping broadcasts) by routing (rather than switching)
> closer to the customer.

Yes, that's unfortunately almost impossible in this case because 
customer needs to use most of his vlans in multiple rooms in the 
datacenter. Maybe we give the customer an own routerport and split him 
from the general L2 infrastructure..


Best,
Jeff