Cisco Systems 3750E manual Configuring the Number of Equal-Cost Routing Paths, 38-77

Chapter 38 Configuring IP Unicast Routing

Configuring Protocol-Independent Features

The default configuration is CEF or dCEF enabled on all Layer 3 interfaces. Entering the no ip route-cache cef interface configuration command disables CEF for traffic that is being forwarded by software. This command does not affect the hardware forwarding path. Disabling CEF and using the debug ip packet detail privileged EXEC command can be useful to debug software-forwarded traffic. To enable CEF on an interface for the software-forwarding path, use the ip route-cache cef interface configuration command.

Caution Although the no ip route-cache cef interface configuration command to disable CEF on an interface is visible in the CLI, we strongly recommend that you do not disable CEF or dCEF on interfaces except for debugging purposes.

Beginning in privileged EXEC mode, follow these steps to enable CEF or dCEF globally and on an interface for software-forwarded traffic if it has been disabled:

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode.
Step 2
	ip cef	Enable CEF operation on a Catalyst 3560-E switch,
	or	or
	ip cef distributed	enable dCEF operation on a Catalyst 3750-E switch.
Step 3
	interface interface-id	Enter interface configuration mode, and specify the Layer 3
		interface to configure.
Step 4
	ip route-cache cef	Enable CEF on the interface for software-forwarded traffic.
Step 5
	end	Return to privileged EXEC mode.
Step 6
	show ip cef	Display the CEF status on all interfaces.
Step 7
	show cef linecard [detail]	Display CEF-related interface information on a
	or	Catalyst 3560-E switch, or
	show cef linecard [slot-number] [detail]	Display CEF-related interface information on a
		Catalyst 3750-E switch by stack member for all switches in the
		stack or for the specified switch.
		(Optional) For slot-number, enter the stack member switch
		number.
Step 8
	show cef interface [interface-id]	Display detailed CEF information for all interfaces or the
		specified interface.
Step 9
	show adjacency	Display CEF adjacency table information.
Step 10
	copy running-config startup-config	(Optional) Save your entries in the configuration file.

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 see occurrences 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 enable a router to load balance packets over the available paths for more efficient use of available bandwidth. Equal-cost routes are supported across switches in a stack.

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02		38-77