Re: "Renew" in Win95

"Michael J. Lewis" <hosmjl@chevron.com> Thu, 29 February 1996 00:52 UTC

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Date: Wed, 28 Feb 1996 18:27:29 -0600
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From: "Michael J. Lewis" <hosmjl@chevron.com>
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To: Ralph Droms <droms@reef.bucknell.edu>
Cc: fred@speedster.ca.boeing.com, dhcp-v4@bucknell.edu
Subject: Re: "Renew" in Win95
References: <9602282232.AA22991@reef.bucknell.edu>
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The "Renew" button in Windows 95 will unicast a DHCPREQUEST packet to 
extend an existing lease.  It looks just like a T1 DHCPREQUEST packet in
a packet trace and places the address in the 'ciaddr' not 'giaddr' 
field.  As long as the originating server is in place (at the same 
address), the button will work correctly resulting in the lease being 
extended.  This has been tested at our site with multiple servers 
(Microsoft's, Competitive Automation JOIN (Solaris/SunOS), and a couple 
of NetWare based servers.)

The "Renew" button can exhibit different behavior in some cases.  If 
the client currently has no lease, then the "Renew" buttom actually will
broadcast a DHCPDISCOVER for a new address.  In cases when a lease is
still active but the server is down, "Renew" can report a "Server 
Unavailable" condition.  This situation can also occur occasionally if
a lease is allowed to truly expire.

We haven't tested much across subnets.

There should be no reason to utilize the renew button in normal 
operations as the lease should renew on its own.  The only time we've
used it here is in testing various combinations of clients and servers
so that we can trace what a client really does at the T1/T2 times.