[c-nsp] svi autostate issue

Peter Rathlev peter at rathlev.dk
Thu Dec 15 12:45:37 EST 2011

On Thu, 2011-12-15 at 16:41 +0400, Андрей Андреев wrote:
> Some SVI has OSPF adjacencies and some eBGP to clients.
> In period of STP convergence SVI flaps and OSPF/BGP flaps too.

And your STP convergence means that the line-protocol flaps, right? So
it's not the convergence time as such, but simply the fact that the
line-protocol flaps and that this is signalled to the routing processes.

I don't think there's a way to tell OSPF to wait for the usual timeouts
instead of reacting to link down, it's a link-state protocol after all.
But OSPF convergence can be fast too, so my main concern would by CPU
load from the churn.

I don't understand why eBGP would flap though. AFAIK, unless you enable
"neighbor n.n.n.n fall-over", it shouldn't tear down an eBGP session
just becase the line-protocol drops.

A dirty hack would be to use two physical interfaces and a looping cable
to always carry the VLAN(s).

If per-VLAN STP was a possibility, topology changes would at least only
affect the VLANs where it was relevant.

Or ask Cisco to implement "no autostate" on the 6500. :-)


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