To add SQUID Proxy Caching Server support in Mikrotik, Assuming the following Scenario.
DSL MODEM IP = 192.168.1.1
MIKROTIK LAN IP = 10.0.0.1
SQUID LAN IP = 192.168.2.1
I assume that you already have working Mikrotik in place, and Already configured SQUID Server ready, (You can search guides about there configurations at my blog), I will just show you how to interconnect them together so All users browsing port 80 request will go to SQUID for caching facility)