how to test the scalibity and stabilty of ISC DHCP???

Chris Buxton chris.p.buxton at
Tue Dec 6 23:50:49 UTC 2011

I have a similar, but slightly more detailed, question.

How can I calculate how much memory a DHCP server will require, based on the number of addresses and also on the number of failover relationships? I have a client who wants to use several dozen failover relationships (hub and spoke, ~30 spokes) supporting around 35K leases, on a budget box (1 GB memory, small-ish hard drive, 1000 Mbit network).

Does anyone think that will work? Or that it won't work? I'm inclined to think he needs a bigger box as the hub, but I don't have any data to back that up.


On Dec 5, 2011, at 12:00 AM, Simon Hobson wrote:

> ameen.shajahan at wrote:
>>                Also how many dhcp entries can ISC DHCP code would support?
> AFAIK, that is entirely dependent on your hardware. I believe there are users with many 10s of thousands of users.
> CPU capacity is rarely a limit.
> You need memory to store the in memory tables and hashes - basically the more available IPs in pools, the more memory you need. This is (IIRC) largely independent of how many of those addresses are actually leased.
> And then you disk I/O performance to handle the updates. Firstly to update the leases file, secondly to handle the logging. This appears to be the main constraint people hit.
> In terms of testing performance, there are some stress testing tools around - hopefully someone will pop up and suggest which to use.
> -- 
> Simon Hobson
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