Failover strangeness

[Greg G]

David W. Hankins wrote:
> On Wed, Oct 11, 2006 at 12:28:30PM -0400, Greg G wrote:
>   
>>    STOS? I'm not familiar with that.  I see a reference to it in the 
>>     
>
> "Start Time Of Service" - the time at which the server entered
> a given state (in this case, partner-down).
>
>   
   I think that might be part of the problem.  At no time is either 
server going into partner-down.  They never get out of 
communications-interrupted.  The man page says something about forcing a 
server into partner-down, but never gives a specific enough example that 
I can figure out how actually to do it via omapi.  (I still can't figure 
out how to open the partner state object.)  I don't want to have to 
restart the primary server to do it, as I'm somewhat allergic to editing 
the lease file.


>>     Hmmm.  I'm really looking for redundancy, so that either of the dhcp 
>> servers can serve up the lease for these clients.   Both servers are
>> getting the request (via ip-helper), and I don't want both of them
>> offering the lease.  That could get ugly.
>>     
>
> Actually even with failover there are known conditions when both
> servers will answer...in communications interrupted when the client
> is sensed to be in the INIT state.  I think both servers answer
> when the client is REBINDING regardless of server state.
>
> Clients deal with it well, and DHCP packet load is never significant.
>
> Lots of people do this.  ISC's network does this.  No one reports
> problems.
>   
   Probably so.  So far, I haven't had this actually occur.  One server 
handles it while the other says that the peer is handling it.

> By the way, that config option was intended to facilitate
> experimentation with isc dhcp clients, where you can specify a
> requested lease time, or any other similar client.  Just to get
> some leases into the reserved state to see how they work.  There's
> no really good real world use case for it I think.
>   
   OK.  The client devices definately aren't running the ISC client.

-Greg G