H3C Technologies H3C S12500 Series Switches - Manual (Page 34)

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NOTE:
You can configure settings such as IP address on a loopback interface. For more information, see Layer
3—IP Services Configuration Guide.
Configuring a null interface
Introduction
Null interfaces are completely software-like logical interfaces. Null interfaces are always up. However,
they can neither forward data packets nor have IP addresses and link layer protocols configured on them.
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. Null interface provides you a way to filter packets. That is,
you can simply transmit unwanted traffic to a null interface rather than applying ACLs.
For example, by executing the ip route-static 92.101.0.0 255.255.0.0 null 0 command (which configures
a static route leading to a null interface), you can have all the packets destined to the network segment
92.101.0.0/16 discarded.
Configuration procedure
To configure a null interface:
Step Command Remarks
91. Enter system view. system-view N/A
92. Enter null interface view. interface null 0
Interface Null0 is the default null
interface on a switch. It can neither
be created nor removed.
93. Set the interface description. description text
Optional.
By default, the description of a null
interface is interface name
Interface.
Displaying and maintaining loopback and null
interfaces
Task Command Remarks
Display information about loopback
interfaces.
display interface [ loopback ] [ brief
[ down ] ] [ | { begin | exclude |
include } regular-expression ]
display interface [ loopback
[ interface-number ] ] [ brief
[ description ] ] [ | { begin | exclude |
include } regular-expression ]
Available in any view.