Router Interface
CCNA R & S

Router Interface Naming Convention

Cisco routers use different types of interfaces like Serial, Fast Ethernet, Giga Ethernet, and Console and each of them has different features and basic purposes.

A single router may not have all of them but can contain more than one, like once router may contain serial, Giga-Ethernet and console Faster Ethernet interface, in routers types of interfaces are more as compared to switch but the number of interfaces available in the switch is more than the router. The speed of Ethernet is 10Mbps, Fast Ethernet is 100 Mbps while Giga Ethernet has 1Gbps.

Back in the old days, we used to have routers who do not have modular support, But the latest versions have support for it where the modules can be added as per required. Like the old routers of 2500 series were not modular while 4000 series router are modular.

Modular router Non Modular router
Modification of interfaces can be done Modification of interface is not possible
Mostly used at core and distribution layer Mostly used at access layer

Difference between a modular and non-modular router

In the fixed interface router, the interface naming sequence is the type of slot/port number. The slot number begins with zero(o) and port number also begins with Zero, as a modular card with two serial interfaces may have the name of serial 0/0 and serial 0/1.
In order to view  all interface on any switch or router use the following command,

The interfaces on Cisco 2950 Switch

It is really important for any network engineer to be familiar with the naming convention because they are in the middle of network meltdown usually they face the problem of remembering the device name and IP addresses, so in this regard by understanding the device naming convention really helps to diagnose the issue more appropriately.

Also, read…

Voice interface numbering in Cisco 2600 series routers

The voice interfaces are named a bit differently than WAN interfaces they are described as below.

Chassis slot/module of voice slot/voice interface

Let say if there is channel voice network module installed in chassis slot 1 the interfaces will be as

  • 1/0/0 — Chassis slot 1/ voice module slot 0/voice interface 0
  • 1/0/1– Chassis slot 1/ voice module slot 0 /voice interface 1
  • 1/1/0 –Chassis slot 1/voice module slot 1/ voice interface 0
  • 1/1/1 –Chassis slot 1/voice module 1 / voice Interface 1

The logical slot number for WIC (WAN interface Card) is always 0, the configuration of any interface can be done by navigating to Global configuration mode-> interface configuration mode.

route interface configuration mode

As per snap attached above the router is in interface configuration and configurations can be done as per required.


Download Router Interface Naming Convention in pdf – Click here