Configuring A Null Interface; Configuring An Inloopback Interface; Displaying And Maintaining Loopback, Null, And Inloopback Interfaces - HP 6125XLG Configuration Manual

Configuring a null interface

A null interface is a virtual interface and is always up, but you can neither use it to forward data packets
nor can you configure it with an IP address or link layer protocol. The null interface provides a simpler
way to filter packets than ACL. You can filter undesired traffic by transmitting it to a null interface instead
of applying an ACL. For example, if you specify a null interface as the next hop of a static route to a
specific network segment, any packets routed to the network segment are dropped.
To configure a null interface:
Step
1. Enter system view.
2. Enter null interface view.
3. Set the interface description.
4. Restore the default settings for
the null interface.

Configuring an inloopback interface

An inloopback interface is a virtual interface created by the system, which cannot be configured or
deleted. The physical layer and link layer protocol states of an inloopback interface are always up. All
IP packets sent to an inloopback interface are considered packets sent to the device itself and are not
further forwarded.
Displaying and maintaining loopback, null, and
inloopback interfaces
Execute display commands in any view and reset commands in user view.
Task
Display information about the specified or all
loopback interfaces.
Display information about the null interface.
Display information about the inloopback
interface.
Clear the statistics on the specified or all loopback
interfaces.
Clear the statistics on the null interface.
Command Remarks
system-view N/A
Interface Null 0 is the default null interface on the
device and cannot be manually created or
removed.
interface null 0
Only one null interface, Null 0, is supported on the
device. The null interface number is always 0.
description text The default setting is NULL0 Interface.
default N/A
Command
display interface [ loopback [ interface-number ] ] [ brief
[ description ] ]
display interface [ loopback ] [ brief [ down ] ]
display interface [ null [ 0 ] ] [ brief [ description ] ]
display interface [ inloopback [ 0 ] ] [ brief [ description ] ]
reset counters interface loopback [ interface-number ]
reset counters interface [ null [ 0 ] ]
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