Re: Auto MDI/MDI-X + conference rooms + bored == loop

[Chuck Anderson <cra () WPI EDU>]

On Fri, Mar 26, 2010 at 03:33:56PM -0700, Owen DeLong wrote:
> Switches that support STP?

Yes, "soho" or "desktop" switches I mean.  Apparently Netgear GS105's 
do not do STP at all, at least they don't claim to.

> There are switches that have STP protection such that they are
> portfast until they see an inbound BPDU and then revert to
> spanning tree on that port (it blocks, listens, learns, then
> forwards if appropriate).

Do the ports so configured also send BPDUs such that a loop on a 
"desktop" switch uplinked to that port will cause the port to see its 
own BPDUs and revert to STP Blocking?  Even if that is the case, I 
think the detection of BPDU and subsequent transition to Blocking will 
happen too slowly.  By then the damage is already done upstream in the 
collapsed L2/L3 core.