[e2e] TCP Option Negotiation

Ralph Droms rdroms at cisco.com
Wed May 23 08:55:24 PDT 2001

At 08:19 AM 5/23/2001 -0600, Vernon Schryver wrote:
> > From: Ralph Droms <rdroms at cisco.com>
> > ...
> > I have experience with DHCPRELEASE being correctly implemented in both the
> > Windows 98 and 2000 DHCP clients...
>How do you cause Windows 98-ME to issue a DHCPRELEASE?

The winipcfg application (which, I think, is standard issue with Windows 
98) issues a DHCPRELEASE in response to the "Release" button.  There is 
also a version of winipcfg for Windows 2000.  "ipconfig /release" also 
works in Windows 2000.

>[...] I'd also appreciate a hint about what Microsoft
>means by the private and presumably entirely kosher option #251.
>I'm not convinced that it is incorrect for a personal computer to never

If I parsed your sentence correctly, you are right: a correctly implemented 
DHCP client might never issue a DHCPRELEASE message.

However, as there are times at which a DHCPRELEASE is useful, it belongs in 
the protocol.  I've most often seen DHCPRELEASE used to work around 
misconfigured DHCP servers or poorly implemented DHCP clients that do not 
correctly notify a mobile DHCP client that it has moved to a new wire.

- Ralph

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