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Beginner

show cdp neighbors command shows two devices connected through the same local port

show cdp neighbors command shows two devices connected through the same local port?

I have a Cisco 3560 that when I issue the "show cdp neighbors" command I get the following results:

Switch1#show cdp neighbors

Device ID            Local Intrfce         Holdtme   Capability        Platform   Port ID

Switch2             Gig 0/3                   169               S I             WS-C3560-4Gig 0/4

Switch3             Gig 0/3                   96                 S I             WS-C3560-4Gig 0/2

the question is why is this showing that Gig0/3 is being used twice to  connect to two different devices.  I have verified there is no hub  connected to this port and in fact Switch3 is not connected to Switch1  at all yet it still shows up in the CDP table.

I have cleared the CDP table on every device at this location and still get the same results.  Any ideas or thoughts?

4 REPLIES 4
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Hall of Fame Expert

Try disconnecting the cable and reconnecting it back.  That might clear CDP.  I have seen it where the CDP doesn't show the neighbor at all and by disconnecting and reconnecting the cable, it works fine.

HTH

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Beginner

Hi Jinoy,

Is there a patch panel between these switches?  Can you get them connected together without anything in between using a brand new cross over cable?  I would want to rule out layer 1 / cabling.

Thanks!

Nick

Nick Bonifacio CCIE #38473
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Beginner

If you have any non CDP aware gear in the mix CDP frames are forwarded to all ports like any other multicast.  I ran into this will Dell switches in between two Ciscos already...

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Second Adams remark via some Extreme gear also.

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