[Kea-users] Performance with many subnets and reservations

Tino Lehnig tino.lehnig at contabo.de
Mon Nov 20 08:59:09 UTC 2017

We have deployed Kea 1.3 in our environment with ~300 subnets using the 
shared networks capability and I would like to provide some feedback on 
performance. Note: We exclusively use host reservations in a MySQL 
database. There are no dynamic address pools. Leases are stored in a file.

We are at point where everything is working fine, but I am concerned 
that Kea will probably not scale well with an increasing amount of 
subnets in its current design. When enabling the debug log, I can see 
that Kea queries the database multiple times for each DHCP request. 
There is one query for each configured subnet. This has quite the impact 
on processing time as each request causes 300 database queries in our 
scenario. Queries are small and the query cache keeps disk I/O at a 
minimum, but CPU utilization is fairly high for Kea and MySQL.

If it is possible at all, it would probably be better to have Kea do 
only one query for the whole hosts table instead of separate queries for 
each subnet. If you any other suggestions for me, I'd appreciate that as 


Kind regards,

Tino Lehnig

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