Failover concept clarification

[Nicholas F Miller]

I have a question about failover behavior. If one of the DHCP servers  
goes offline does the server that is still up handle the existing  
leases for the down server? I know the server that is still up cannot  
offer leases from the downed server's free leases pool. But when a  
client, with an existing lease from the down server, asks to renew the  
lease will the server that is still up handle the renewal?
_________________________________________________________
Nicholas Miller, ITS, University of Colorado at Boulder



On Jul 7, 2009, at 12:04 PM, David W. Hankins wrote:

> On Tue, Jul 07, 2009 at 04:49:54PM +0530, pat wrote:
>> What will be the time to expire before my secondary responds to all  
>> the
>> clients request?
>
> Load balancing is only engaged in 'normal' state.  In all other
> operating states, the server will always answer as best it can.
>
>> is it 00hr:09min:41sec + 1800 sec = 00hr:39min:41sec so my  
>> secondary server
>> will wait for 39min and 41 sec before answering all my clients  
>> request.
>>
>> how do i calculate the STOS+MCLT time.
>
> You got this right.  This time effectively determines when the
> partner's free lease pool will be available for allocation to new
> clients, although this is actually a case-by-case basis on each
> individual lease.  The actual time is TSFP+MCLT or STOS+MCLT,
> whichever is further in the future.  Generally free leases have a
> TSFP that is in the past, so STOS+MCLT is the effective measure.
>
> However, expired leases, or leases reaching expiry, may have a
> TSFP that is still in the future (the TSFP lags ahead of lease
> expiration so that leases may be extended to lease-times greater
> than MCLT).
>
> STOS+MCLT doesn't affect LBA.
>
> -- 
> David W. Hankins	"If you don't do it right the first time,
> Software Engineer		     you'll just have to do it again."
> Internet Systems Consortium, Inc.		-- Jack T. Hankins
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