Configuring an IPv4 Route

Static route

Configure a static route to a specific network or host address

Null route

Configure a "null" route to discard IP traffic to a specific network or host address:

Discard traffic for the destination, with ICMP notification to sender
Discard traffic for the destination, without ICMP notification to sender

Syntax:


[no] ip route dest-ip-addr / mask-length [next-hop-ip-addr | vlan vlan-id | reject | blackhole] [metric metric] [distance1-255] [tag-value tagval] [name <name-str>]

Allows the addition and deletion of static routing table entries. A route entry is identified by a destination (IP address/mask length) and next-hop pair. The next-hop can be either a gateway IP address, a VLAN, or the keyword "reject" or "blackhole".

A gateway IP address does not have to be directly reachable on one of the local subnets. If the gateway address is not directly reachable, the route is added to the routing table as soon as a route to the gateway address is learned.

dest-ip-addr / mask-bits

The route destination and network mask length for the destination IP address. Alternatively, you can enter the mask itself.

For example, you can enter either 10.0.0.0/24 or 10.0.0.0 255.255.255.0 for a route destination of 10.0.0.0 255.255.255.0.

next-hop-ip-addr

This IP address is the gateway for reaching the destination. The next-hop IP address is not required to be directly reachable on a local subnet. (If the next-hop IP address is not directly reachable, the route will be added to the routing table as soon as a route to this address is learned.)

reject

Specifies a null route where IP traffic for the specified destination is discarded and an ICMP error notification is returned to the sender.

blackhole

Specifies a null route where IP traffic for the specified destination is discarded and no ICMP error notification is returned to the sender.

distance

Specifies the administrative distance to associate with a static route. If not specified, this value is set to a default of 1. (Range: 1 to 255)

tag

Specifies a unique integer value for a given ECMP set (destination, metric, distance.)

name <name-str>

Assigns a name to a static route.

The no form of the command deletes the specified route for the specified destination next-hop pair.

Examples