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New Member

Receiving CDP but not ICMP

Hello all, this seems like a dumb question but it kind of has me stumped......

When browsing the network I can actually perform a sh cdp nei detail and see devices but if I try to ping the device I am unsuccessful, what's the reason for this? Any ideas? I just had a thought.......(writing things down brings good thoughts I guess) CDP is a propagated protocl therefore just because I can see the device via cdp doesn't mean I can ping due to the fact that the device may not be directly this true? Just thinking out loud but any ideas would be greatly appreciated.



Re: Receiving CDP but not ICMP

CDP only runs at layer 2. While it may pick up an neighbors IP address, that does not imply that you can connect via IP.

New Member

Re: Receiving CDP but not ICMP


CDP is not propagated through the network only to directly attached neighbours. IF you do see the neighbour via CDP this means they are physically conneted and teh port are up. No you need to set IP -addrss on the interfaces.

Are you working with router or switched or a combination?

What kind of interfaces are you using.

Kind regards,

Hans Grutter

New Member

Re: Receiving CDP but not ICMP

Any access list or firewall rule that denies ICMP?

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