[c-nsp] CDP -- more than one neighbor on the same port?

[Furnish, Trever G]

> -----Original Message-----
> From: Gert Doering [mailto:gert at greenie.muc.de]
> Sent: Wednesday, December 12, 2007 2:12 PM
> To: Furnish, Trever G
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] CDP -- more than one neighbor on the same port?
> 
> Hi,
> 
> On Wed, Dec 12, 2007 at 01:58:07PM -0500, Furnish, Trever G wrote:
> > Under what circumstances would CDP show more than one neighbor on
the
> > same port?
> 
> "dumb switch" in between (that floods CDP packets to all ports,
instead
> of handling them itself).
> 
> > We have a site where the local IT staff is claiming that a switch
> > interface (switch2 g0/2) is connected directly to exactly one other
> > cisco switch, but 'show cdp nei' on switch 2 shows three other
> > switches as neighbors on that interface.
> 
> Maybe it's a cisco dumb switch (linksys?) that doesn't speak CDP.

Jeff's guess was actually correct -- it's gigastack, which seems to be a
10Gbps half-duplex bus.

> It will quite happily traverse anything that is not actively handling
> these frames.

Thanks.  That's what I suspected -- I just thought I had read that it
wouldn't traverse non-cdp switches, and I never understood why that
would be true.  It's nice to have some confirmation that makes sense.

> gert

Thanks, Gert.