independent servers on same subnet

[Carl Karsten]

Simon Hobson wrote:
> Japhy Bartlett wrote:
> 
>> The way to "decide" is in the routing, no?
> 
> No, by definition, if the servers are in the same subnet, they will 
> receive the same broadcast messages from clients. There are only two 
> ways to do this :
> 
> 1) Configure each client with information on which server(s) it should 
> accept a lease from. However, in the general case this can't be done as 
> most client lack this capability.
> 
> 2) Configure each server with information on which clients to serve and 
> this is the commonly used setup. Generally, as long as you can define a 
> group of clients, you would configure one server to ignore them and 
> serve the rest, and configure the other server to serve only these 
> clients and ignore the rest. Selecting clients can be done by any 
> criteria you can configure a rule for in both servers - based on MAC 
> address, client-id, something unique sent in the packet, the presence of 
> a specific option in the request, and many more permutations.

Those were the 2 thing I thought would work, but I just heard a third, and dare 
I say it seems like a reasonable config:

 > You are forgetting about redundancy. Many sites will
 > replicate reservations across DHCP servers.  You have to do it manually,
 > but there are tricks.
 > I run two DHCP servers without reservations, I just use two scopes that
 > don't overlap.

It cuts the usable size of your pool in half, cuz if one server is always faster 
(like when the other goes down) it's pool is the pool.

That is the only down side I can think of.  am I missing anything?

Carl K