DHCP: New lease upon bootup???

  • Thread starter Thread starter aldo
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A

aldo

WinXP Pro requests a new DHCP lease upon every bootup
eventhough it got one previously, which was good
for 30 days. Are there some net settings that would
prevent XP from requesting a new lease upon every boot and
keep the one it acquired 'till it expired?
 
Aldo,

Windows will automatically acquire a new lease upon bootup, because it
releases its lease when it shuts down. The only way to prevent acquiring a
new lease is to statically define your IP (by not using DHCP).

Leases aside, to prevent getting a new IP address (if your DHCP server gives
you a new one each time you restart) you can statically define your IP or if
you have access to the DHCP settings you can create an exception to give you
the same IP, based on your NIC's MAC address.
 
I had a feeling someone was going to suggest fixing my IP.
THX Matt,
Question: whats different, as far the networking is
concerned, with XP and ME. I had the same DHCP
configurations as I do with XP, 'cept I do notice that
some other stuff is enabled like LMCHOST???, yet with ME
my PC held the lease 'till it expired. Although I retained
the same IP w/ME, leasing would operate as it normally
should, meaning that my PC would acquire a lease and then
request for another upon its 30 day expiration.
 
XP should still hold its lease for the duration of the lease if the computer
is kept on. It attempts to renew the lease when 50% of the lease has
expired. If it can't do this successfully it will try again after 87.5% of
the current lease has expired.

If you think about it, if you turn the computer off for say 5 days, when you
start it back up it would be reasonable to expect that it would not have the
same lease as before with 5 less days on it, but to have acquired a new
lease-- as if it were obtaining an IP for the first time. The expectation
is on the DHCP server to remember the configuration details.

I am not sure as to the differences of the TCP/IP stacks for Millennium and
XP, but they are each based off of two seperate versions, ME was based off
of the 9x stack (although updated), and the XP stack is based off of the
Windows 2000 stack, which came from the NT codebase.

I am interested as to what medium you are connected to and receiving an
IP... an ethernet network with a DHCP server, or through a cable or DSL
service.
 
Well, I'm connected to a DI-624 router, which in turn is
connected to a Cable modem, SB4100. My ISP is dynamic as
is my routers DHCP settings. I tried using a static DHCP
IP so that my PC would have a fix IP, which dramatically
improves bootup (8 secs), but cannot access the Internet.
Probably some missing DNS settings ???
I understand that the DHCP client should use the leased
IP 'till it expires, but for some reason my PC gets
another one ???

If you don't mind would you email (e-mail address removed) to
continue? Though, I have no prob using the...hopefully
someone else could benefit from this discussion. 8)
 
aldo said:
WinXP Pro requests a new DHCP lease upon every bootup
eventhough it got one previously, which was good
for 30 days. Are there some net settings that would
prevent XP from requesting a new lease upon every boot and
keep the one it acquired 'till it expired?
Click to expand...

Aldo, all,

I have exactly the reverse problem. My laptop does not ask for a
new IP address when coming out of standby mode. As it has
meanwhile moved to a different LAN (from work to home, for
example), it causes IP address conflicts because, for example,
the work IP address is already taken by another computer in the
home.

Any ideas how to prevent that? I'm now trying to remove the
network cable before going into standby, and that seems to
circumvent the problem, but I would prefer to solve than work
around it.

Hans-Georg
 
Hans-Georg,
For your situation, if I'm understanding it correctly, I
could only recommend using the "Repair" feature on the
Local Area Connection since your Laptop already acquired
an IP from the DHCP server. I'm not sure if you could
config your NIC to scan for a new DHCP host when it sense
a connection. This normally done upon boot, but I know
there is a way to "Release" an IP and then "Renew". I
know I've been in that situation with an NT client where
I would use the CMD prompt to ipconfig /release ... then
typed ipconfig /renew to get another IP for the client
PC, which didn't require me to reboot. If you use the
HELP on XP it will detail those functions (ipconfig) for
U....... I think the "Repair" function does that, or at
least, I've been using it like that while I've been
tinkering with my net connections
 
Perhaps XP is just more location-aware?

Mobile devices are more common now.
When the machine boots, who's to say it is still on the
same network it was when it shut down?

A DHCP renewal at boot time would catch the case where
it had moved. It would get a NACK and then do a fresh request.
 
Aldo, all,
I have exactly the reverse problem. My laptop does not ask for a
new IP address when coming out of standby mode. As it has
meanwhile moved to a different LAN (from work to home, for
example), it causes IP address conflicts because, for example,
the work IP address is already taken by another computer in the
home.

Any ideas how to prevent that? I'm now trying to remove the
network cable before going into standby, and that seems to
circumvent the problem, but I would prefer to solve than work
around it.

Hans-Georg
Click to expand...



Coming out of standby != reboot, and I suspect that it was
not designed to be moved from lan to lan in standby.

Removing the network cable will disable the interface, and
re-plugging it will re-enable it and trigger a round of DHCP.

I suspect there's not a solution other than to shut down rather
than go into stby when moving from lan to lan.
 
Ron,
are you saying, when the lan cable is reconnected after
being disconnected that XP will try to acquire another IP
(essensially releasing the IP it had)?

If that were the case, wouldn't it be equivalent to
releasing and then renew a lease through the command
prompt?
 
Could I interpret your reply as there is no way to get XP
to retain its given IP even when its lease expires (as an
example) a year from now? I ask because that process of
acquisition makes for a 40+ sec bootup, yet if I fix the
IP it boots within 15sec. With that said, I know what your
going to reply, but I'm curious why XP won't retain its
lease.
 
aldo said:
Ron,
are you saying, when the lan cable is reconnected after
being disconnected that XP will try to acquire another IP
(essensially releasing the IP it had)?

If that were the case, wouldn't it be equivalent to
releasing and then renew a lease through the command
prompt?
Click to expand...

Aldo,

actually that's what I observe here. Seems to be normal behavior
as designed. Makes sense as well.

Some WAN routers are nice enough to try to keep the IP addresses
stable and linked to the MAC addresses (in some, like the old
SMC 7004 ABR, you can even set them through a user managed MAC
to IP address matching table), but many routers and other DHCP
servers just don't care.

Hans-Georg
 
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