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New Member

Neighbor IP Address is missing in "show cdp neighbor detail"

Hi Sir,

Two switches, SwitchA and SwitchB, are connected to eath other via a VLAN trunk.

SwitchA is a Catalyst 3508G-XL. SwitchB is a Catalyst 2948. Both running Cisco IOS software.

The VLAN trunk is established using "on" mode because the switches have different VTP domains. Both are VTP transparent mode. Both ends of the trunk pass all VLANs and having the same dot1q Native VLAN.

Both switches are on the same management VLAN. They can ping each other's management IP address.

The issue is, when doing "show cdp neighbor detail" on SwitchA, the IP address of SwitchB is not shown. When doing "show cdp neighbor detail" on SwitchB, the IP address of SwitchA can be seen. What could be the cause?

Please help.

Thank you.

B.Rgds,

Lim TS

3 REPLIES
New Member

Re: Neighbor IP Address is missing in "show cdp neighbor detail"

Sorry. It should be the other way round, as follows:

When doing "show cdp neighbor detail" on SwitchA (C3508G-XL), the IP address of SwitchB can be seen. When doing "show cdp neighbor detail" on SwitchB (C2948), the IP address of SwitchA is not shown.

Thank you.

B.Rgds,

Lim TS

Cisco Employee

Re: Neighbor IP Address is missing in "show cdp neighbor detail"

Can you post and configs and sh cdp neig detail outputs?

Purple

Re: Neighbor IP Address is missing in "show cdp neighbor detail"

Sometimes doing a "clear interface" on each end of the link will fix some cdp issues . I use it when cdp works on one end but nothing shows from the other , this seems to be prevalent on older models like 2924's and maybe like your 3508 . Something to try .

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