Used Cisco Network Module with one Fast Ethernet port. For Cisco 2600/3600/3700 series routers only.
Cisco 1-Port Fast Ethernet Network Module, NM-1FE-TX
Ideal for a wide range of LAN applications, the Fast Ethernet network modules support many internetworking features and standards. The 1-port Fast Ethernet network module offers a single auto-sensing 10/100TX connection via an RJ-45 connector.