cache_peer selection

[Soporte Técnico AlemNet <soporte@xxxxxxxxxxxxxxx>]

How can i make cache_peer selection for blocks of ip of my network ?
Example.

192.168.0.xxx i want to use
cache_peer 172.16.1.1

192.168.1.xxx i want to use
cache_peer 172.16.1.2

192.168.1.xxx i want to use DIRECT

any help 

?