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

[Gert Doering]

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.

> Am I correct in assuming that this should only happen if the g0/2 port
> is connected to a hub?

Or any non-CDP-aware switch.

> I realize CDP's not supposed to traverse switches, although I'm not
> quite sure *why*.  The destination's always 01000ccccccc, but I'm not
> quite clear why such a frame wouldn't be flooded by a non-cdp-aware
> switch.

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

gert

-- 
USENET is *not* the non-clickable part of WWW!
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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