Reference Guide

Interfaces | 373
To view Loopback interface configurations, use the show interface loopback number command in the
EXEC mode.
To delete a Loopback interface, use the
no interface loopback number command syntax in the
CONFIGURATION mode.
Many of the same commands found in the physical interface are found in Loopback interfaces.
Also refer to IP Prefix Lists on page 79.
Null Interfaces
The Null interface is the virtual interface which is always up, but no traffic is transmitted through this
interface.There is only one Null interface.
To enter the INTERFACE mode of the Null interface, use the following command in the
CONFIGURATION mode:
The only configurable command in the INTERFACE mode of the Null interface is the
ip unreachable
command.
Port Channel Interfaces
Port channel interfaces support link aggregation, as described in IEEE Standard 802.3ad.
This section covers the following topics:
• Port channel definition and standards
• Port channel benefits
• Port channel implementation
• Configuration task list for port channel interfaces
Port channel definition and standards
Link aggregation is defined by IEEE 802.3ad as a method of grouping multiple physical interfaces into a
single logical interface—a Link Aggregation Group (LAG) or port channel. A LAG is “a group of links
that appear to a MAC client as if they were a single link” according to IEEE 802.3ad. In FTOS, a LAG is
referred to as a port channel interface.
Command Syntax Command Mode Purpose
interface null 0
CONFIGURATION Enter the INTERFACE mode of the Null interface.