Thu, Apr 07, 2005 at 09:01:16AM -0400, Christos Zoulas:
> 
> Artsi is probably right. If you are connected on a vlan switch, and you
> don't have fast convergence (what is the cisco term for that?), then when
> NetBSD erroneously brings down and up the interface to set promiscuous
> mode, the switch restarts the vlan negotiation and that can take up to
> a minute. The solution is to fix the drivers to do the minimal work to
> enter/exit promiscuous mode where possible without affecting link state.

my experience has been that the forwarding delay with a cisco switch is
spanning tree, where the port is thrown into blocking mode when it comes
up and until the SPT can determine that the port does not represent a
topology loop.

afaik, portfast is the cisco hack for ports that are part of a bridge group
and thus must run SPT and reduces the learning phases of SPT.  otherwise,
just disable SPT on the port (or entire switch).

http://www.cisco.com/warp/public/473/12.html