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Windows 2000 DHCP problem?

Posted on 2004-03-25
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Last Modified: 2010-03-18
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( We have several sites (IP segments) in our NT4 Domain. When one of our mobile users goes from one site to another, he does not get automatically an IP address from our DHCP server when connecting to the network on that site. The IP address of the previous site stays on the ethernet interface. A manual IPCONFIG /release /renew is needed to get an new IP address on the new sigment/site. So DHCP is responding on DHCP requests and working fine.)

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Added by GBHOLS:

We have the same issue, although ipconfig /release /renew does not pick up the address for that segment... it holds onto the previous address from the site before!

The only things that have changed is that we have deployed 3com 4400SE switches to each site, but disabled rapid spanning tree and igmp snoop mode. we have enabled QOS for RDP tcp(3389)

dhcp helper-address has been added correctly to our cisco routers.

the dhcp server is accepting and issuing addresses according to the dhcp log files on the server, just the wrong ones for roaming users! ( i.e. last sites )

Any help will be refunded with points.

Thanks

Kevin P
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Question by:gbhp
11 Comments
 
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Expert Comment

by:Gareth Gudger
ID: 10677797
So you need to find a way to easily change IPs between networks?
If so, try http://www.netswitcher.com/


Or is it not able to get an IP after you have tried a release a renew?
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Author Comment

by:gbhp
ID: 10678054
Thanks for your comment, but we would rather not give our users control over network configurations.

There has to be an easy solution to this that does not require additional software..

It's just that we have been looking hard for it and our heads hurt!


Kevin P
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LVL 16

Expert Comment

by:JammyPak
ID: 10678434
one question - are you doing this with a separate DHCP server per segment, or do you have multiple scopes on a single DHCP server and helper addresses?
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Author Comment

by:gbhp
ID: 10678468
Multiple scopes on one dhcp server ( win2ksrv )

just to add, when we do a /release /renew on the adaptor it gives us the same ip address of the last site we were on!
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LVL 16

Expert Comment

by:JammyPak
ID: 10678617
do you have Network Monitor or any other sniffer tool there?

Try to capture one of the DHCPREQUEST packets in this scenario, and see if there is a value in the giaddr field. This is the field that tells the DHCP server which subnet the request originated from, and it should be populated with the ip address of the router that the DHCP client is going through to get to the DHCP server. This packet would be between the router and the DHCP server...
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Author Comment

by:gbhp
ID: 10678638
Alas no, and the site is 450 miles away......

I may be able to sniff on our router though
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Author Comment

by:gbhp
ID: 10678726
Found that the computer in question has the little icon in dhcp manager ( previous site visited ) Address leases stating " Active lease, DNS dynamic update pending. This address is not available for lease by the DHCP server. "

Could this cause an issue?

0
 

Author Comment

by:gbhp
ID: 10679366
Ok, I think we have found a resolution,

Our addresses are set to an 8 day lease, the dhcp server was holding onto the addresses in question, we have now cut the lease period down to a day for each site, this may cause a little more traffic in the morning, but what the hey!

Thanks for your help, I will close.
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LVL 16

Expert Comment

by:JammyPak
ID: 10679931
dumb question, but what if I'm on one subnet in the morning and move to another in the afternoon?

this workaround may do the job for you, but it doesn't really address the fact that things are working the way they 'should'.

anyway, if you want to PAQ it, I have no complaints...
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