I am using a 2811 router as my border router. I have an Ethernet 100MB coming into it for my Internet from my ISP. I am using an ASA5500 firewall to protect my networking and NAT is being done on that. The 2811 is just a border router not doing NAT or anything else just routing traffic from the Fa0/0 interface to the fa0/1 interface. If I test to the ISP's test site I get 90MB at local sites but 30-60MB to there remote sites. They say this is due to windowing as the distance increases. The 2811 seems to be running fine. CPU is 20% during the day and drops to almost 0 at night. Memory is 6%.
Could the reason I am not seeing higher through put the 2811? Should I be using a beefer router?