and 3600), so these would make excellent access routers. The 3600 and 4000 series have more
port density than the smaller routers and have RISC processors for better performance on packet
manipulation. Finally, the 7000 series, which includes the 7200 and 7500 routers, and the
Gigabit Switch Router (GSR) provide the highest forwarding capacity.
LAPB, Frame Relay, and X.25. ATM requires a specific interface due to the SAR function. For
instance, the 3600 series supports ATM support at OC-3 speeds and higher; some slower ATM
interfaces are supported on access routers.