Re: DHCP, dual NIC, DHCP failure

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From: KM (konstmor_at_nospam_yahoo.com)
Date: 02/25/05 

Date: Fri, 25 Feb 2005 01:23:48 -0800

Henry,

I have a bad feeling that the 5 minutes for the DHCP client to retry getting an ip address if the initial attempt failed is
hardcoded.
I haven't seen any related registry flags and Googling showed similar opinion coming from number of people.

If getting IP at the boot time is so inconcistent on your system, have you throught of postponing the dhcp client service load until
some major part of the boot process is done? Basically, you have the DHCP service disabled (or set to manual) and then start it with
your own application/script/command, backing up with ipconfig /renew, somewhere at the boot process (either in a service that
depends on most of other services, or through a [HKLM\...\Run] command, or etc.). Then you can add some Sleeps in your application
code before you start the DHCP service to make sure the network stack is up and running. You can experiment with the code to get the
best and consistent result.

KM

> With my target devices I've found there is about a 50% probability that dynamic
> IP addresses are not obtained for at least 6 minutes. The devices are industry
> standard Compact PCI blades (PICMG 2.16) that use an Intel dual port network
> controller (82546EB). Many well known vendors including Kontron, Momentum, DTI
> and others have the same blade architecture. With a basic remote boot load
> containing only standard components except for the XPe NIC driver obtained from
> the Intel support site, there is an apparent race that causes the target to
> abandon the DHCP protocol about 50% of the time. The problem appears about
> equally likely in SP1 and SP2.
>
> I conducted many tests with a 2.0GHz Pentium-M blade supplied by DTI, a cPCI
> backplane, and a Win2003 server that was both boot server and DHCP server. The
> proper sequence of DHCP messages for the client to obtain an IP address is:
> Client Server
> ------ ------
> Discover
> Offer
> Request
> Ack
> It appears to me that the DHCP client runs independent threads to execute this
> protocol for each interface. In about 1/2 the cases the protocol is abandoned
> by the client after a server offer. When the protocol is abandoned, it is
> always abandoned for both interfaces. The client then restarts the protocol 5
> to 6 minutes later and it typically succeeds for both interfaces however I have
> seen one case where it failed on the second attempt and in this case the target
> had no IP addresses for 14 minutes after boot.
>
> Note that in a PXE boot scenario a DHCP address is obtained for an interface
> twice -- once by the PXE BIOS client and once when the downloaded OS takes
> control. DHCP never fails when executed under PXE, it only fails when executed
> under XPe.
>
> My client has just ordered $800,000 worth of equipment including 224 of the CPU
> blades that I have tested. It is completely unacceptable that it can take 6
> minutes or more for these blades to be network enabled after a boot. I really
> need help on this one.
>
> TIA,
> Henry

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