10-15-2012 02:19 AM - edited 03-07-2019 09:27 AM
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?
10-15-2012 04:30 AM
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
10-15-2012 04:56 AM
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
10-15-2012 07:44 AM
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...
10-15-2012 10:05 AM
Second Adams remark via some Extreme gear also.
04-21-2024 12:59 PM
Update Cisco patches and check IOS versions compatibility on all switches.
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