How to pass the svn protocol/Traffic from the Squid

[Avin]

Hi All

         I am using Squid 2.5STABLE. It's  work fine but the In our office they use TortoisesSVN for downloading plugins from net. Problem is that my proxy is not allow to pass svn traffic. They need plugins for there Ruby On Rails projects.  Whenever I try to download some SVN plugins from client side It give error Host unknown.  So anybody tell me What is solution of that problems.
                                                   
 Avin