Configuring IP Addressing
Figure 34-2 IP Classless Routing
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 34-3 No IP Classless Routing
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
Catalyst 3750 Switch Software Configuration Guide
34-8
128.0.0.0/8
128.20.4.1
IP classless
128.20.0.0
128.20.2.0
128.20.4.1
34-3, the router in network 128.20.0.0 is connected to subnets 128.20.1.0, 128.20.2.0, and
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.
Chapter 34
Configuring IP Unicast Routing
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