Is there a way to hold DHCP addresses in XP?

[dane775]

I used to know quite a bit about PC's...not so much anymore. All apologies if this is a really basic question.

With NT and Win2k...DHCP addresses used to stay in my machine until a new one was learned or it got flushed.

With XP my machine loses it's IP and goes to a 169.x.x.x address if the NIC gets disconnected (not sure how long it needs to be disconnected before it reverts) for a bit.

Here's the problem...we have layer 2 switches in our network that occasionally hiccup or do CPU switchovers. During that period the NIC cards on attached work stations get disconnected causing the DHCP IP addys to revert to the default IP (169.x.x.x)

Is there a way to increase the time the machine holds its IP...or a way to make it act the way Win2k and NT do??

Thanks in advance for any assistance.

 

[SimonDavies]

It all comes from the DHCP server, it's the DHCP server that determines the lease time, if you have a short lease time then you have an even shorter period where the NIC can be disconnected, the lease renewal period actually starts at 50% of the lease life.

Have a look on the server to see what your lease period is and if you can increase that time (ideally to something like 7-10 days). I have seen sites where they actually set leases to 24hours.

SimonD.

The real world is not about exam scores, it's about ability.

 

[SimonDavies]

The 169.254.*.* is called an APIPA address, do a google or whatis on it to learn more.

Also have a look at your ipconfig /all results to see how long the lease period is from there.

SimonD.

The real world is not about exam scores, it's about ability.

 

[dane775]

That sounds quite logical, but doesn't explain why Win2k machines don't have the same problem pulling addy's from the same server.

I don't think the lease time will affect how long an XP machine will hold that address if the Ethernet cable gets disconnected from the NIC card..(which is basically what's happening when the L2 switch does a CPU switchover)..before reverting to that standard 169.x.x.x IP XP machines all default to.

 

[dane775]

re: APIPA address. Thanks....by googling that I should be able to get some info on how quick it reverts to that address and if there's anything I can do to get it to hold its DHCP addy a bit longer.

Thanks again...

 

[Sympology]

When it reconnects, does it stay as a 169? Or does it go back to a true IP?
Of course you could always fix the cause as oppossed to apply the cure. The switches must be causing havoc on the network, so much for 5 9's !
Stu..

Only the truly stupid believe they know everything.
Stu.. 2004

 

[dane775]

Stu - It's not as much of a 5 9's issue as it is an upgrade/failover testing issue. That's when it was noticed and the concern then became: how long before it comes back up.

re: APIPA. Yes, it stays at the 169.254.x.x address until it decides to query for the presence of a DHCP server. According to Microsoft, an XP machine should check for a DHCP server within 5 minutes of implementing the APIPA address, so it's not a huge issue.

I was able to find a registry hack that will disable that feature (APIPA addy). I doubt that we'll go with the registry change, but it's nice to know why the stations aren't reconnecting ASAP, and how to work around this problem if need be.

 

[usakjw]

The registry hack you mentioned (not sure what it is but I have hard of it) will only disable the APIPA feature. I do not think it will solve your problem. If you disable APIPA then you just wont get an address at all.

Sounds to me that their is an issue with the switch. How long has the switch been on line? Do you or have you recently move several computers around, the MAC table could be corrupted which could be corrcted with a reboot of the switch. Check for firmware updates from the manufacture of the switch. If it is a Cisco switch or other commercial switch (something other than Linksys, D-Link, Net Gear or other home user equipment), check its configuration make sure their are no VLANs etc configured that are not supposed to be.

Are their any routers between the DHCP and the systems that are having the problem If so you will need either another DHCP server or a DHCP relay agent.

KJW

 

[dane775]

usakjw - re: registry hack. Hmmm...you could be right about that - haven't tested to see if it will act just like a Win2k/NT box when that feature is disabled.

re: firmware update - that's one of the things that initiates the problem. Anytime you do an upgrade involving a reboot there's a brief moment when the NICs are disconnected from the Passport. Win2k and NT machines will hold their DHCP addy (for a while at least)...XP machines revert to the APIPA addy.

I know it's an Operating System issue because we tested a Win2k machine and didn't have a problem. The XP machines sit there for a few minutes before they look for a DHCP server...then they're okay afterward.

But that could take up to 5 minutes during which there's a lot of panic from folks who don't know why things aren't working.