Cisco 3845 - Security Bundle Router

29-6
Cisco ME 3800X and 3600X Switch Software Configuration Guide
OL-23400-01
Chapter 29 Configuring IP Unicast Routing
Configuring IP Addressing
Figure 29-2 IP Classless Routing
In Figure 29-3, the router in network 128.20.0.0 is connected to subnets 128.20.1.0, 128.20.2.0, and
128.20.3.0. If the host sends a packet to 120.20.4.1, because there is no network default route, the router
discards the packet.
Figure 29-3 No IP Classless Routing
To prevent the switch from forwarding packets destined for unrecognized subnets to the best supernet
route possible, you can disable classless routing behavior.
Beginning in privileged EXEC mode, follow these steps to disable classless routing:
Host
128.20.1.0
128.20.2.0
128.20.3.0
128.20.4.1
128.0.0.0/8
128.20.4.1
IP classless
45749
128.20.0.0
Host
128.20.1.0
128.20.2.0
128.20.3.0
128.20.4.1
128.0.0.0/8
128.20.4.1
Bit bucket
45748
128.20.0.0
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
no ip classless Disable classless routing behavior.
Step 3
end Return to privileged EXEC mode.