Cisco Catalyst 3560-X Software Configuration Manual page 1055

Chapter 1 Configuring IP Unicast Routing
Figure 1-2
128.20.1.0
In Figure
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 1-3
128.20.1.0
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:
Command
Step 1 configure terminal
Step 2 no ip classless
Step 3 end
OL-25303-03
IP Classless Routing
128.0.0.0/8
128.20.4.1
128.20.0.0 IP classless
128.20.2.0
128.20.4.1
1-3, the router in network 128.20.0.0 is connected to subnets 128.20.1.0, 128.20.2.0, and
No IP Classless Routing
128.0.0.0/8
128.20.0.0
128.20.2.0
128.20.4.1
128.20.3.0
Host
128.20.4.1
Bit bucket
128.20.3.0
Host
Purpose
Enter global configuration mode.
Disable classless routing behavior.
Return to privileged EXEC mode.
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
Configuring IP Addressing
1-9