lease renewal activity

Jamie Savage jsavage at
Fri Mar 30 13:38:14 UTC 2012

      Thanks for your responses.   I had not thought of the possibility of 
the ACK from the DHCP server not making it back to the client for whatever 
reason.  I'm not familiar with what the client does in this case.  Simon, 
in this situation, you've suggested the client will DHCPREQUEST more 
aggressively and then finally give up and start all over with a 

Jamie Savage  |  Senior Communications Technician  |  University 
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From:   Simon Hobson <dhcp1 at>
To:     Users of ISC DHCP <dhcp-users at>
Date:   03/29/2012 04:34 PM
Subject:        Re: lease renewal activity
Sent by: at

Jamie Savage wrote:

>Discover, Offer, Request is good.  Subsequent requests 
>at the 5 minute half-life.......again...all is well......until 10:22 
>where the requests are no longer 5 minutes apart and then a discover 
>is initiated at 10.24 and then the 5 minute half-life requests start 

My guess is that <something> happened to prevent packets being 
received. So renewal at 10:14 went OK, but renewal at 10:19 (50% of 
lease used) failed. Since you say you didn't touch it, I guess you've 
no idea if any other network traffic was working.

At 10:22, about 75% of lease used, the client starts to renew more 
vigorously. Finally, at 10:24:46 (7 seconds before lease expires), 
the client gives up and broadcasts a Discover. At this point, the 
<something> that broke the network got fixed (by the act of the DHCP 
client configuring the interface ?) and the client then continued 

As to what the <something> is, no ideas !

Simon Hobson

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