lease length

Jeff Haran jharan at Brocade.COM
Wed Feb 3 18:35:39 UTC 2010


> -----Original Message-----
> From: dhcp-users-bounces+jharan=brocade.com at lists.isc.org 
> [mailto:dhcp-users-bounces+jharan=brocade.com at lists.isc.org] 
> On Behalf Of sthaug at nethelp.no
> Sent: Sunday, January 31, 2010 1:16 PM
> To: dhcp-users at lists.isc.org; dhcp at paz.bz
> Subject: Re: lease length
> 
> > what is the maximum seconds that can be placed in lease times?
> > I would like my customers to have their leases for an extended
> > period to reduce dhcp traffic.
> 
> You should be able to offer them 2^32-1 (4294967295) which basically
> means infinite.
> 
> Steinar Haug, Nethelp consulting, sthaug at nethelp.no
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> 

However, based on my testing it would appear that the leases offered by dhcpd wont be quite that long.

What I found was that the longest lease dhcpd would offer to a client extends to the end of the Unix epoch in 2038.

A long time, but not infinite.

Also, the all 1s lease time => infinity seems to be an IPv6 only thing. I couldn't find a reference in the IPv4 DHCP RFCs to any special meaning for a lease time == 0xffffffff, though curiously if you look at the source code to some of the popular clients (e.g. dhcpcd), they seem to think that there is.

Jeff Haran
Brocade Communications



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