Cisco devices, routers, and switches typically interconnect many devices. For this reason, these devices have several types of ports and interfaces. These ports and interfaces are used to connect cables to the device.

The connections on a Cisco router can be grouped into two categories:

The figure highlights the ports and interfaces of a Cisco 1941 ISR G2 router.

Like many networking devices, Cisco devices use light emitting diode (LED) indicators to provide status information. An interface LED indicates the activity of the corresponding interface. If an LED is off when the interface is active and the interface is correctly connected, this may be an indication of a problem with that interface. If an interface is extremely busy, its LED is always on.