Loopback Interfaces; Null Interfaces - Dell Force10 C150 Configuration Manual

Loopback Interfaces

A Loopback interface is a virtual interface in which the software emulates an interface. Packets routed to it
are processed locally. Since this interface is not a physical interface, you can configure routing protocols
on this interface to provide protocol stability. You can place Loopback interfaces in default Layer 3 mode.
To configure a Loopback interface, use the following command in the CONFIGURATION mode:
Command Syntax
interface loopback
number
To view Loopback interface configurations, use the
EXEC mode.
To delete a Loopback interface, use the
CONFIGURATION mode.
Many of the same commands found in the physical interface are found in Loopback interfaces.
See also Configuring ACLs to Loopback on page

Null Interfaces

The Null interface is another virtual interface created by the E-Series software. There is only one Null
interface. It is always up, but no traffic is transmitted through this interface.
To enter the INTERFACE mode of the Null interface, use the following command in the
CONFIGURATION mode:
Command Syntax
interface null 0
The only configurable command in the INTERFACE mode of the Null interface is the
command.
Command Mode
CONFIGURATION
no interface loopback
Command Mode Purpose
CONFIGURATION Enter the INTERFACE mode of the Null interface.
Purpose
Enter a number as the loopback interface.
Range: 0 to 16383.
show interface loopback
command syntax in the
number
151.
command in the
number
ip unreachable
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