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Catalyst 3750 SwitchSoftware Configuration Guide
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Chapter38 Configuring IP Unicast Routing
Configuring Protocol-Independent Features
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.
Even though the router automatically learns about and configures equal-cost routes, you can control the
maximum number of parallel paths supported by an IP routing protocol in its routing table. Although the
switch software allows a maximum of 32 equal-cost routes, the switch hardware will never use more than
16 paths per route.
Beginning in privileged EXEC mode, follow these steps to change the maximum number of parallel
paths installed in a routing table from the default:
Use the no maximum-paths router configuration command to restore the default value.
Configuring Static Unicast Routes
Static unicast routes are user-defined routes that cause packets moving between a source and a
destination to take a specified path. Static routes can be important if the router cannot build a route to a
particular destination and are useful for specifying a gateway of last resort to which all unroutable
packets are sent.
Step6 show ip cef Display the CEF status on all interfaces.
Step7 show cef linecard [slot-number] [detail] Display CEF-related interface information by stack member for
all switches in the stack or for the specified switch.
(Optional) For slot-number, enter the stack member switch
number.
Step8 show cef interface [interface-id] Display detailed CEF information for all interfaces or the
specified interface.
Step9 show adjacency Display CEF adjacency table information.
Step10 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 router {bgp | rip | ospf | eigrp} Enter router configuration mode.
Step3 maximum-paths maximum Set the maximum number of parallel paths for the protocol routing
table. The range is from 1 to 16; the default is 4 for most IP routing
protocols, but only 1 for BGP.
Step4 end Return to privileged EXEC mode.
Step5 show ip protocols Verify the setting in the Maximum path field.
Step6 copy running-config startup-config (Optional) Save your entries in the configuration file.