16
NOTE:
You can configure settings such as IP addresses and IP routes on loopback interfaces. For more
information, see
Layer 3—IP Services Configuration Guide
and
Layer 3—IP Routing Configuration
Guide
.
Configuring a null interface
Introduction to the null interface
A null interface is a completely software-based logical interface, and is always up. However, you
cannot use it to forward data packets or configure an IP address or link-layer protocol on it. With a
null interface specified as the next hop of a static route to a specific network segment, any packets
routed to the network segment are dropped. The null interface provides a simpler way to filter
packets than ACL. You can filter uninteresting traffic by transmitting it to a null interface instead of
applying an ACL.
For example, by executing the
ip route-static 92.101.0.0 255.255.0.0 null 0
command (which
configures a static route that leads to null interface 0), you can have all the packets destined to the
network segment 92.101.0.0/16 discarded.
Only one null interface, Null 0, is supported on your switch. You cannot remove or create a null
interface.
Configuration procedure
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter null interface
view.
interface null 0
The Null 0 interface is the default null interface on
your switch. It cannot be manually created or
removed.
3.
Set the interface
description.
description text
Optional
By default, the description of a null interface is
interface name
Interface.
4.
Restore the default
settings for the null
interface.
default
Optional
Displaying and maintaining loopback and null
interfaces
Task Command
Remarks
Display information about
loopback interfaces.
display interface
[
loopback
] [
brief
[
down
|
description
] ] [
|
{
begin
|
exclude
|
include
}
regular-expression
]
display interface
loopback
0
[
brief
[
description
] ] [
|
{
begin
|
exclude
|
include
}
regular-expression
]
Available in any view
