How can I redirect all traffics to Squid3 on Ubuntu 12.04 enterprise server from cisco 2901 router that is acting as gateway for my company's Internet.

I have cisco 2901 router running as a gateway for internet.  I have configured squid3 on my ubuntu 12.04 enterprise server and it owrks good. My question is how can I configure my router so that all traffic shall be forwarded to the squid server.