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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter22 Configuring IP Unicast Routing
Configuring Protocol-Independent Features
Beginning in privileged EXEC mode, follow these steps to enable CEF on an interface after it has been
disabled:
To disable CEF on an interface, use the no ip route-cache cef interface configuration command.
This is an example of output from the show ip cef privileged EXEC command:
Switch# show ip cef
Prefix Next Hop Interface
0.0.0.0/32 receive
1.0.0.0/24 attached GigabitEthernet0/2
1.0.0.0/32 receive
1.0.0.1/32 receive
1.0.0.55/32 1.0.0.55 GigabitEthernet0/2
1.0.0.255/32 receive
2.0.0.0/24 attached GigabitEthernet0/3
2.0.0.0/32 receive
2.0.0.1/32 receive
2.0.0.55/32 2.0.0.55 GigabitEthernet0/3
2.0.0.255/32 receive
224.0.0.0/4 drop
224.0.0.0/24 receive
255.255.255.255/32 receive
This is an example of output from the show adjacency privileged EXEC command:
Switch# show adjacency
Protocol Interface Address
IP GigabitEthernet0/3 2.0.0.55(5)
IP GigabitEthernet0/2 1.0.0.55(5)
Configuring the Number of Equal-Cost Routing Paths
When a router has two or more routes to the same network with the same metrics, these routes can be
thought of as having an equal cost. The term parallel path is another way to refer to occurr en ce s of
equal-cost routes in a routing table. If a router has two or more equal-cost paths to a network, it can use
them concurrently. Parallel paths provide redundancy in case of a circuit failure and also enables a router
to load balance packets over the available paths for more efficient use of available ba ndwid th.
Although the router automatically learns about and configures equal-cost routes, you can cont rol the
maximum number of parallel paths supported by an IP routing protocol in its routing table.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Enter interface configuration mode, and specify the
Layer 3 interface to configure.
Step3 ip route-cache cef Enable CEF on the interface.
Step4 end Return to privileged EXEC mode.
Step5 show ip cef Display the CEF status on all interfaces.
Step6 show adjacency Display CEF adjacency table information.
Step7 copy running-config startup-config (Optional) Save your entries in the configuration file.