I have a 3745 router that I am going to use for CLNS routing. Currently the router has Rel 12.2(15) ZJ2. This does not support CLNS routing (IS-IS). the main purpose of this router is going to be terminal server access, OSI address routing, and possibly VOIP. What would be the best IOS to load on this router. It currently only has 128mb of DRAM and 64mb of Flash.