DHCP not working for Masterclock NTDS44 when connected to 2960S/3560-X switches

[fuhrersk8]

Hello guys;

This is the problem: A clock Masterclock model NTDS44 gets ip via DHCP when connected to a Catalyst 4507 chassis, but when connected to access switches models 2960-S and 3560-X it does not.

Both, the Catalyst 4507and the 2960S/3560-X switches interfaces are on same VLAN and have same DHCP server and same configuration in terms of VLAN, speed/duplex, spanning-tree, etc.

When a PC is connected to the same ports it gets its ip, but the clock won't. 

Question: Is there a restriction, bug, etc., that prevents the Masterclock model NTDS44 to gets DHCP when connected to Catalyst models 2960S/3560-X?

Thanks for your support.

Regards, 

[Jose Solano]

Hi,

There should not be a major difference if the configuration is the same, I would suggest you to run the following debugs while connecting the clock device into the 4500 and then into the 2960 or 3560 and the compare the DHCP process to see if we can spot anything abnormal on the 4500:

debug ip dhcp server packets

debug ip dhcp server events

Hope this helps.

[fuhrersk8]

Hi and thanks for your reply;

      We managed to get it working by disabling/enabling spanning-tree portfast.

Thanks for your support.

Regards,