[UKLAN] RE: XP clients sometimes ignore DHCPOFFERs
Hagedorn at uni-koeln.de
Thu Mar 16 15:10:27 UTC 2006
--On 15. März 2006 16:34:26 -0500 "King, Michael" <MKing at bridgew.edu>
> Actually, I think it's the home routers that are killing you. :-)
I thought of that. One thing I have noticed is that the leases form the
home routers seem to be very long-lasting, i.e. several days. I haven't
been able to ascertain whether XP saves leases between restarts.
> There is another Microsoft "Feature" you failed to mention:
> If the DHCP client has previously obtained a lease from the DHCP server,
> the client tries to renew any unexpired lease with the DHCP server. If
> the client fails to locate any DHCP server, it attempts to ping the
> default gateway listed in the lease. If this succeeds, the client assumes
> it has not been moved and uses that lease. The client then seeks to
> automatically renew the lease when half of the lease time has expired.
> If the attempt to ping the default gateway fails, the client assumes that
> it has been moved to a network that has no DHCP services currently
> available, such as a home network and it configures itself. It then
> automatically keeps trying to find a DHCP server every five minutes.
> Can these clients / you ping 192.168.1.1 (or 192.168.0.1)? If you can,
> that's why they won't let go of they're IP and take a new one.
No, they can't. We use "proper" addresses for our subnets. However, I
wonder if the second paragraph might not be an indication of what goes
wrong: if I understand this correctly it says that if the client can't ping
the gateway from the old lease it will *first* configure itself (I take
that to mean "assign itself a link-local IP") and only then five minutes
later try to find a DHCP server!?
AFAIK, just waiting for the client to get a lease does not work, either,
but I can't swear to that.
Thanks, Sebastian Hagedorn
.:.Sebastian Hagedorn - RZKR-R1 (Gebäude 52), Zimmer 18.:.
Zentrum für angewandte Informatik - Universitätsweiter Service RRZK
.:.Universität zu Köln / Cologne University - Tel. +49-221-478-5587.:.
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