Using The Null Interface; Prefix Lists - Juniper IP SERVICES - CONFIGURATION GUIDE V 11.1.X Configuration Manual

Using the Null Interface

You can use access control lists to filter undesired traffic. Another way to handle
undesired traffic is to send it to the null interface. The router automatically creates
the null interface, which is always up, cannot be deleted, and acts as a data sink. In
other words, the null interface cannot forward or receive traffic. However, the CLI
does allow you to access the null interface.
The E Series router creates the null interface by default; you do not have to manually
create it. You can direct traffic to the null interface by specifying the null 0 keywords
instead of a next-hop or destination address when you configure routes.
interface null
ip route

Prefix Lists

A prefix list is a sequential collection of permit and deny conditions that apply to IP
or IPv6 addresses. Like an access list, the router tests addresses one by one against
the conditions in a prefix list. The first match determines whether the router accepts
host1(config)#ipv6 static-route table-map map4
Use the no version to delete the table map.
See ip static-route table-map.
See ipv6 static-route table-map.
Use to access the null interface.
The null interface is a data sink; it does not accept or forward traffic.
Although you can access the null interface, you cannot configure any values for
it or delete it.
Example
host1(config)#interface null 0
host1(config-if)#
There is no no version.
See interface null.
Use to configure a static route and redirect traffic from it to the null interface.
Example
host1(config-if)#ip route 10.10.20.5 null 0
Use the no version to remove the static route.
See ip route.
Chapter 1: Configuring Routing Policy
Using the Null Interface
33