Strange DHCP client identifier

Unanswered Question
Mar 8th, 2007

I am troubleshooting DHCP between server and client (both Cisco IOS). I have discovered, that server sees client under completely nosensical client identification:

R1#sh ip dhcp binding

Bindings from all pools not associated with VRF:

IP address Client-ID/ Lease expiration Type

Hardware address/

User name 0063.6973.636f.2d30. Apr 01 2001 10:40 PM Automatic




Yes, the client id server sees is "3062.302e.6332.3838.2e31.3637.312d.4661.30" instead of little more conventional "00b0.c288.1671". What's up here? This thing makes manual binding impossible, as that long number is not accepted in "client-identifier" on server.

Edit: No, I wasn't cut'n'pasting properly, that long client-id can be entered into pool configuration. So that solves the problem, and the only think that remains unanswered for me is what were Cisco thinking, when they decided that client-id is going to be this kind of crazy stuff instead of plain MAC.

I have this problem too.
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sundar.palaniappan Thu, 03/08/2007 - 13:52

Some Cisco networking devices use a DHCP client identifier format that is different from the format used by networking devices running Cisco IOS release 12.4(1) or newer.

Ref link:

But, you should be able to bind that full (long) address to the the client IP in your DHCP pool configuration and I've done that before. If you are having problems refer to this link:




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