DHCP issue

Sp00n

Sp00n

Sp00n

Soldato
Joined
18 Oct 2002
Posts
18,296
Location
Brighton
I was wondering if you guys could shed some light on an issue i have with one of my users.

Basically they go home and connect wirelessly to their router (they may have also connected via a wire initially) and get given an ip address via dhcp, now when they come back in the office and plugin to the network they get a ip conflict because they are still holding on to 192.168.0.2 from when they were connected at home.

The only way to resolve it is to release the ip and then renew it.

I can't think of any reason why this would happen because of the way dhcp is designed but i'm thinking it might be a communication issue with the dhcp server in the office which would be why it doesnt pick up a new one straight away.

...but i don't know, does anyone have any ideas?
 
My users get this from time to time - At home the DHCP lease will be set to 7 days so its not looking for a new IP I guess?

Ways to force a change er pass - Logon script to do this if its a major issue?
 
I suppose i could change the DHCP release time on the home router to something like 8 hours which would help out a bit but even still, i thought a new dhcp server would over-ride current IP settings but maybe not.
 
I can only think its not looking for a new IP because it has x days on current lease. Lucky I only have the sales guys that pop into the office from time to time.
 
just create a shortcut on the user's desktop. "ipconfig /release", run that before shutting down.

if using xp pro, you could even set it up to run at logoff using gpedit.msc :)
 
marc2003 said:
just create a shortcut on the user's desktop. "ipconfig /release", run that before shutting down.

if using xp pro, you could even set it up to run at logoff using gpedit.msc :)
Click to expand...

Yea i suppose this is an option and i created a bat file containing:

ipconfig /release
ipconfig /renew


...but the point is it shouldn't be doing that and getting the client to run a bat file isn't really very professional so maybe running it at logon might be the answer.
 
Could you not set the lease to a shorter time, like 1 day or whatever suits the working time between taking the computer/laptop home then back to the office again?

Alex
 
Clarkey said:
they hibernating the machine? It should renew the DHCP every reboot.
Click to expand...

So if they don't actually reboot the machine then it will try and keep its dhcp leased ip from the home router?

That sounds like it could be the one, i shall enquire on monday!

Many thanks
 
Yeah, as far as the laptop knows it's still attached to the "router at home". Hibernate / Standby puts the laptop in a static state, rebooting obviously requires that the laptop obtains an IP on start-up.
 
Even though when he is at hoem he's connected wirelessly, then when he's in the office its over a wire.

I would have thought the cable being plugged in would instigate a new lease?
 
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