Hello, I just started working at a muni-ISP that is using a Linux box as thier router because their CISCO 3640 croaks too often. They (the City) does not want to buy a new router because of cost, but they would like to use a CISCO router. So, after looking around online (my CISCO classes were only with 2500 series and 1700 series routers) I found some CISCO 4000's and CISCO 3640's on the Internet. The 3640's cost a lot more than the 4000's so there must be some major difference between the two. Only thing I can see is that the 3640's can handle more DRAM than the 4000s.
What do we need the router to do? Well, we have a T1 line and a 3Mbps Microwave line (Will soon be upgraded to 8Mbps). Both backbones are routed with BGP. The T1 has over 106000 learned routes on the 3640, so I assume having a fair share of memory is a good thing (Current route space used is 17MB).
Any help would be helpful.