Traffic Forwarding IPv4 Static Route Examples

The following series of static route input examples are based upon the following route configuration:

# **** VRF default (default) ****
configure terminal
!
# Static routes configured on routed interfaces
 ip route 33.1.1.0/24 133.1.1.2 interface vlan.0.333 1
 ip route 33.1.2.0/24 144.1.1.2 interface vlan.0.444 1
 ip route 192.168.1.0/24 blackhole 1
 ip route 192.168.1.0/30 reject 1
 ip route 192.168.1.4/30 100.1.1.3 interface vlan.0.100 1
!
# Static routes configured on non-routed interfaces
 ip route 10.0.0.0/8 10.21.128.1 interface vlan.0.4000 1
 ip route 134.141.0.0/16 10.21.128.1 interface vlan.0.4000 1
!
exit
!

The following example enters a static route with no next-hop interface specified. The route prefix and length is 33.1.1.0/24 and the next-hop is 133.1.1.2.

System(rw-config)->ip route 33.1.1.0/24 133.1.1.2

This is a legacy format. You are not prevented from entering the route in this format, but the behavior has changed as follows:

• A search of all configured subnets for a subnet containing the next-hop 133.1.1.2 is performed. That search will determine that this next-hop is on interface vlan.0.333 as indicated in the configuration above. The configured route will be as if you had entered the command:

  System(rw-config)->ip route 33.1.1.0/24 133.1.1.2 interface vlan.0.333

• Should an interface not be found for this next-hop, the route will be configured as if you specified the route as a recursive route as follows:

  System(rw-config)->ip route 33.1.1.0/24 133.1.1.2 recursive

The following example enters a static route for prefix and length 33.1.2.0/24 with a next-hop of 144.1.1.2, but this time specifying the interface, vlan.0.444, that the next-hop is on:

System(rw-config)->ip route 33.1.2.0/24 144.1.1.2 interface vlan.0.444

The following example configures a blackhole route for prefix and length 192.168.1.0/24. Packets destined for blackhole routes are silently dropped. An ICMP network unreachable message is not sent to the packet source.

System(rw-config)->ip route 192.168.1.0/24 blackhole

The following example configures a reject route that overlaps the 192.168.1.0/24 blackhole route for prefix and length 192.168.1.0/30. In this case, packets destined for this next-hop are also dropped, but an ICMP network unreachable message is sent to the packet source:

System(rw-config)->ip route 192.168.1.0/30 reject

The following example configures an overlapping route allowing frames to 192.168.1.5 and 192.168.1.6 to be forwarded to next-hop 100.1.1.3 on interface vlan.0.100:

System(rw-config)->ip route 192.168.1.4/30 100.1.1.3 interface vlan.0.100

Use the show ip route command to display IP routes for this device. Route display can be narrowed by specifying route type: connected, ospf, rip, or static. The show ip route command output for this series of inputs is:

System(rw-config)->show ip route
Host IP Route Table for VRF default
Codes: C-connected, D-dynamic, H-host, S-static
       *-no forwarding interface
S*     10.0.0.0/8               10.21.128.1         vlan.0.4000
C*     10.21.128.0/17           10.21.130.151       vlan.0.4000
H      10.21.130.151            10.21.130.151       lo.0.1
S      33.1.1.0/24              133.1.1.2           vlan.0.333
S      33.1.2.0/24              144.1.1.2           vlan.0.444
C      100.1.1.0/24             100.1.1.2           vlan.0.100
H      100.1.1.2                100.1.1.2           lo.0.1
C      101.1.1.0/24             101.1.1.2           vlan.0.100
H      101.1.1.2                101.1.1.2           lo.0.1
H      127.0.0.1                127.0.0.1           lo.0.1
C      133.1.1.0/24             133.1.1.1           vlan.0.333
C      133.1.1.0/24             direct              vlan.0.333
H      133.1.1.1                133.1.1.1           lo.0.1
S*     134.141.0.0/16           10.21.128.1         vlan.0.4000
S      192.168.1.4/30           100.1.1.3           vlan.0.100
Number of routes = 15

Use the show ip protocols command to display information about IP protocols running on this device.