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DHCP Helper not working with Windows 2008R2

Anyone experience DHCP not working when pointed to a Windoes 2008R2 server? It works perfectly when pointed to a 2003 server.  DHCP does work when PC is connected to the same VLAN as the Windows 2008R2 server.  All we did was add a new ip helper-address pointing to the Windows 2008R2 server. We are using an older 4506 with a slightly ancient IOS.

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New Member

Re: DHCP Helper not working with Windows 2008R2

Hi Gary,

I don't know of any specific issues but since it occurs in Win2008 but not in Win2003 it sounds like there must be something different in the implementation of handling DHCP requests when using IP helper.

For sure if the switch software is relatively old it's worth upgrading to rule out any possible known bugs at this point.

If investigation is needed we can run some dhcp based debugs during the issue, we can run those same debugs using the Win2003 device (when it's working) to compare the outputs.

Specifically we could look to run:

#deb ip dhcp server packet

#deb ip dhcp server events

Collect those when trying to get an IP address from the server. Maybe it will give us a clue as to why it's not working.

To summarise, upgrading the IOS makes sense, and maybe get those debugs. We might also look at getting some SPAN captures as well.

finally, can you ensure 'service dhcp' is enabled globally?



New Member

Did you ever find the

Did you ever find the solution to this issue?  I'm experiencing this now as we are moving from a 2003 DHCP server to a 2008 R2 one.

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