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DHCP Multihomed Clients problem

By lwebb ·
Normally, my DHCP server gives me very few problems...

Symptoms:
User tries to log in in the morning and it takes 5-7 minutes to get an IP address.
The DHCP server has issued them one, but they either don't take it, or take it and drop it as soon as they boot to desktop completely... and wind up with the APIPA address.

Ok, so basically the Client says "Gimme an address!" and the DHCP is sending NACK's "I gave you one, hoser! Wait till the lease is up to get another!".

I have to go and manually delete the IP address before the DHCP server will issue a new one and normally the client picks it up right away after that. Rarely, I have to do the whole ipconfig /release-renew thing on the client.

The client machines are all newer laptops with at least 2 NIC's, onboard gigabit and wireless-G. Some have additional NIC's for other purposes.
Most are Dell, but not all.

Due to it hosing the Users when they travel, I can't put "wait for network at startup" requirements in Group Policy. Note: Doing this for my DESKTOPS cured the exact same problem!!!

The server is Win2k3 and all clients are WinXP.

I seem to remember a MS solution to this, but I've searched and I've Googled and I just am at the end of the rope.

Thanks!

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by lwebb In reply to DHCP Multihomed Clients p ...

Normally, they get a number after 5-7 min, sometimes upwards of 15 despite the lease being 4 hours....

Weird. Eventually, the DHCP server hands them a new one anyway or they decide to use the one their issued.

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by Zen37 In reply to DHCP Multihomed Clients p ...

Have you sniffed the traffic when the laptop boots? What steps have you seen occuring between the two?

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by Zen37 In reply to

Hummm, My guess would be that the problem is more at your workstation than at the DHCP network, unless the packet it send to the workstation is not complete for some reason.

Or, there is a problem with the fact that you have multiple cards on your stations. Have you tried eliminating (disable) all but one interface on the machines to see if the problem persist?

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by lwebb In reply to DHCP Multihomed Clients p ...

Initally the DHCP server sends back an ACK, but the laptop continues to send out Unicast DHCP requests to which the server responds with NACK's.

They're on the same logical network, so there is no Relay Agent.

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by lwebb In reply to DHCP Multihomed Clients p ...

It's one of those "never happens when the IT guy is around" things.

I.E. the problem never occurs with MY laptop and later in the day the problem tends to get less and less.

I mean, I've seen it happen and know how to fix it:
Delete the lease from the DHCP server
But it doesn't happen all the time (except in during the morning login rush)so it's difficult to troubleshoot.

But that's an annoying one-off solution and doesn't address the root of the problem.

My boss swears it's a problem with the ProCurve switch.

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by E.Eliveld In reply to DHCP Multihomed Clients p ...

A fix is to set the MAC adress in the DHCP server on a certain IP adres. And give the workstation a fixed IP adress.

ok, dirty... but it works.

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by lwebb In reply to DHCP Multihomed Clients p ...

Uhh...giving the clients a fixed IP address pretty much defeats the purpose of having DHCP as does reserving numbers for a certain MAC address.

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by howie.erickson In reply to DHCP Multihomed Clients p ...

It sounds like you have network slowdowns. It happens when everyone is trying to log in. You don't specify, but I will assume for the moment that the DHCP server is also a DC. If this is the case, I would try to move the DHCP to either another DC which is less busy or to a member server. It is possible that there is a problem with the switch. It is also possible that the server is overburdened. It would appear that although the server is sending an Ack, the workstation is never sending anything back saying I accept that address. Is there a wireless access point in the network config anywhere? It is also possible that although the workstation is accepting the address initially that the response from the server is not coming. Again either DHCP problem or Network slowdown problem.

Hope this helps.
Howie

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