[e2e] TCP Option Negotiation

Vernon Schryver vjs at calcite.rhyolite.com
Wed May 23 07:19:29 PDT 2001

> 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?  I tried a
bunch of things, but tcpdump never saw one.  For the same irrelevant
and off-topic reasons, 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
issue a DHCPRELEASE.  If you have any doubt that the DHCP server might
not be reallocated using a least recently used policy or if you fear that
DHCP server was not given the required number of IP addresses for its
client population and if you are disconnecting or shutting down only
temporarily, then the right policy is to never issue a DHCPRELEASE and to
just let the lease expire.  If you are a system vendor, the only way
to implement that policy is to leave DHCPRELEASE out of your DHCP

On the other hand, personal computers tend to not disconnected from
networks cleanly, so DHCP servers cannot in any way rely on DHCPRELEASE

Thus, a case can be made that DHCPRELEASE is not useful.  Given the
potential for harm from breaking the TCP quite-time, that implies a case
can be made that DHCPRELEASE be officially decrecated.   Such a move would
probably have to come from this group.

Vernon Schryver    vjs at rhyolite.com

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