Different Types of Interfaces on Cisco Routers

The auxiliary ports, as well as console ports, are used for router management. Routers also have ports for LAN and WAN connectivity. The LAN interfaces usually include Ethernet, Fast Ethernet, Giga Ethernet, Fiber Distributed Data Interface (FDDI), and Token Ring. The following are the details of all types of Cisco router interfaces.


Ethernet is typically the router’s physical interface based on the IEEE 802.3 standard. The port’s operating speed is 10 Mbps, and the media standard for this interface is 10BaseT.

Fast Ethernet

Fast Ethernet is also known as the FE interface. It is an IEEE 802.3u standard-based physical interface. The operating speed of Fast Ethernet is 100 Mbps. The media standard used for the Fast Ethernet interface is 100BaseT.

Gigabit Ethernet

Gigabit Ethernet is also known as the GE interface. This port’s standard is Ethernet IEEE 802.3ab. Gigabit Ethernet can connect at the remarkable speed of 1000mb/s. The media standard used is1000BASE-T

Serial interfaces

A serial interface is a communication interface between two digital systems that transmit data as a series of voltage pulses down a wire. Serial interfaces are typically used for WAN connections from ISP  to host. The serial interface provides connectivity types like Frame Relay, T1, T3, etc.


Fiber Distributed Data Interface (FDDI) is a set of ANSI and ISO standards for data transmission on fiber optic lines in a local area network (LAN). Its range can extend up to 200 km. FDDI networks operate at 100 Mbps speed and use a token-passing mechanism to prevent collisions.

Token Ring

A token ring network is a local area network (LAN) in which all computers are connected in a ring or star topology and pass one or more logical tokens from host to host. Only a host that holds a token can send data, and tokens are released when receipt of the data is confirmed. Token Ring interfaces can operate at either 4 Mbps or 16 Mbps. Token Ring networks were missing from the networking industry a long way back. New Cisco routers do not have a Token Ring interface.

Loopback interface

A loopback interface is a logical, virtual interface in a Cisco Router. This is not a physical interface like a Fast Ethernet or Gigabit Ethernet interface. A loopback interface has essential uses, such as an OSPF Router ID.

Null Interface

A null interface is a virtual interface that discards IP packets to prevent routing loops in the network. We do not assign the IP address to a null interface.