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CDP not propagating from connected Node

We have are experiencing an issue with our Core switch not propagating the CDP neigh to connected nodes. The Core is seeing direct trunk nodes and displays them in the sh cdp neigh. From the node side however we cannot see the Core switch CDP info.

In addition to this (and related) we are having VTP propagation issues as well. Core sw is our single VTP server. I have verified that all nodes are in client, running v2, and in correct vtp domain. The revision number is 10 behind the current on all nodes in the LAN. Have rebooted all nodes, and have tried on several to del vlan.dat and bring back up. This resulted in a pickup of the older VTP rev. Tac was sure we had another server as well, but they have verified the issue.

Tac is pointing the to the CDP issue being the root cause. Has anyone seen this before?

Our Core is a 6509E with lastest IOS.

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6 REPLIES
Hall of Fame Super Silver

Re: CDP not propagating from connected Node

Hello Miles,

both VTP and CDP use native vlan on trunk links.

check native vlan settings on both sides of each L2 trunk.

on new core switch is native vlan permitted on trunk ports?

not permitting the native vlan is a security practice.

Also be aware that it would be wise to have two VTP servers in your network for redundancy.

A VTP server accepts updates with an higher revision number as a client would do.

Hope to help

Giuseppe

Hall of Fame Super Blue

Re: CDP not propagating from connected Node

mlrtexas01 wrote:

We have are experiencing an issue with our Core switch not propagating the CDP neigh to connected nodes. The Core is seeing direct trunk nodes and displays them in the sh cdp neigh. From the node side however we cannot see the Core switch CDP info.

In addition to this (and related) we are having VTP propagation issues as well. Core sw is our single VTP server. I have verified that all nodes are in client, running v2, and in correct vtp domain. The revision number is 10 behind the current on all nodes in the LAN. Have rebooted all nodes, and have tried on several to del vlan.dat and bring back up. This resulted in a pickup of the older VTP rev. Tac was sure we had another server as well, but they have verified the issue.

Tac is pointing the to the CDP issue being the root cause. Has anyone seen this before?

Our Core is a 6509E with lastest IOS.

Miles

I'm sure TAC have already asked for this info but could you post -

1) sh vtp counters  & sh vtp status from the VTP server

can you select one of the client switches and then

2) "sh int trunk" on both the core switch and the client switch

3) can you post the config of just the trunk link from both the core switch and the client switch

Jon

New Member

Re: CDP not propagating from connected Node

Appreciate the responses. I think we are narrowing down our issue to the fiber blade itself within the 6509E. We have several IBM blades in our server room and they are direct connected to the Core sw but via copper instead of fiber. I checked all of these nodes and they were all updating VTP and seeing the Core as a neighbor. We tested just now with a new switch both copper and fiber. The fiber did not build the vlan.dat but the copper did. So we are looking at a firmware issue or an IOS bug.

Thanks for the posts, we had checked out almost every other avenue that was suggested. Tac was actually on our systems yesterday for about 4 hours trying all the same troubleshooting we had worked on.

Hall of Fame Super Silver

Re: CDP not propagating from connected Node

Hello Miles,

to add useful information to this thread:

may you specify the fiber based linecard model and the IOS image running on the C6500?

Your findings are interesting and may be useful for other people.

Hope to help

Giuseppe

New Member

Re: CDP not propagating from connected Node

Model : cisco WS-C6509-E (R7000) processor

IOS Image : Cisco IOS Software, s72033_rp Software (s72033_rp-ADVENTERPRISEK9_WAN-M), Version 12.2(33)SXI

Fiber Line Card : WS-X6748-SFP CEF720 48 port 1000mb SFP Rev. 1.4

Thanks again for the suggestions. We have a test 6500 that we have ordered a another line card for and will update when we find the solution to this issue.

Hall of Fame Super Blue

Re: CDP not propagating from connected Node

giuslar wrote:

Hello Miles,

both VTP and CDP use native vlan on trunk switches.

check native vlan settings on both sides

on new core switch is native vlan permitted on trunk ports?

Also be aware that it would be wise to have two VTP servers in your network for redundancy.

A VTP server accepts updates with an higher revision number as a client would do.

Hope to help

Giuseppe

Giuseppe

You beat me to it I was also thinking about the native vlan hence the requested info on the trunk links.

Miles - do you see any CDP Native vlan mismatch error messages on any of the switches ?

Jon

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