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Lost CDP packet from Cisco 2950 to HP 2824

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David Brousseau
Occasional Advisor

Lost CDP packet from Cisco 2950 to HP 2824

I have an HP 2824 that is running I.08.87.

Connected to the switch are other HP switches (running code pre-LLDP) that are sending CDP packets and a Cisco 2950 that is sending CDP packets.

When I run "debug lldp" on the HP switch, I see the CDP advertisements from the connected HP switches but no CDP advertisement from the Cisco switch.

A packet sniffer proves that the Cisco switch is in fact sending the CDP advertisement.

I have connectivity between the two devices.

I have verified that there is no port authentication (802.1x or web auth) configured on the HP port connected to the Cisco switch.

The HP switch is not running STP. The Cisco switch is running STP and the port connected to the HP switch is in a forwarding state.

What are some things that would cause the HP to not act on the CDP advertisement from the Cisco switch?

Thanks,
--Dave
3 REPLIES
Mohieddin Kharnoub
Honored Contributor
Solution

Re: Lost CDP packet from Cisco 2950 to HP 2824

Hi

Would you try to upgrade to the newer version
I.08.105, i think there was an issue in the command "show LLDP" does not display information learned from CDPv2 packets.

Anyway i think you know that ProCurve stopped supporting the CDP, and some configurations may continue to provide limited read-only support for CDP, and in the 2824 starting from release I.08.74 FEC and CDP transmit removed.

Good Luck !!!
Science for Everyone
David Brousseau
Occasional Advisor

Re: Lost CDP packet from Cisco 2950 to HP 2824

Mohieddin,

Thanks for your reply. I cannot upgrade the HP device as it is not under my control. However, your response made me wonder why the CDPv2 advertisements didn't show up. I experimented by forcing the Cisco to send CDPv1 advertisements. This change caused the HP switch to recognize and handle the CDP packet.

So it reports receiving the CDP packet via "debug lldp". It also shows the neighbor via "show lldp info remote" as well as "show cdp neighbors".

Ultimately, the problem is that this version of firmware doesn't handle CDPv2 packets.

Best regards,
--Dave
David Brousseau
Occasional Advisor

Re: Lost CDP packet from Cisco 2950 to HP 2824

Closed. Switch at the current version does not support CDPv2. Forcing the Cisco switch to advertise CDPv1 fixes the problem.