I need some help sizing out a router for a project I am working on and thought I might be able to get some advice from the community.
Basically, I am connecting to organizations together via a dark fiber connection. At some point in the future, they want to be able to use the line for up to 1Gbps speed, but at the beginning, they are only going to be using 100-500Mbps. I was looking at the 3845 line of routers to use on both sides so that I can do some basic packet filtering to limit traffic coming into each organization (they are terminating into a DMZ but still want to limit what can go down the pipe). When looking at it, it looks like the 3845 only has 45Mbs of sustained throughput. Are there any network module cards that I can get or upgrade the router with to get up to 500Mbs for the initial deployment, then within a couple years upgrade to a larger router than will support the gigabit speed that is needed. We are trying to reduce cost for the initial deployment until the demand rises enough to warrant making the large purchase for gigabit routers. I thought about using some form of L3 switch, but that may not be sufficient since we need to do packet filtering on each side, but it may since the switch has ACL's for the vlan interfaces.
Any help you can give would be appreciated.