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Implementing Frame Mode MPLS

Chapter Description

This chapter covers configuring Cisco Express Forwarding, verifying CEF, troubleshooting CEF, configuring MPLS on a Frame Mode interface, and configuring MTU size in label switching.

This chapter provides information and commands concerning the following topics:

  • Configuring Cisco Express Forwarding
    • - Verifying CEF
    • - Troubleshooting CEF
  • Configuring MPLS on a Frame Mode interface
  • Configuring MTU size in label switching

Configuring Cisco Express Forwarding

To enable MPLS, you must first enable Cisco Express Forwarding (CEF) switching.

Router(config)#ip cef

Enables standard CEF

Router(config)#ip cef distributed

Enables dCEF

Router(config)#no ip cef

Disables CEF globally

Router(config)#interface fastethernet 0/1

Moves to interface configuration mode

Router(config-if)#ip route-cache cef

Enables CEF on the interface

Verifying CEF

Router#show ip cef

Displays entries in the forwarding information base (FIB)

Router#show ip cef summary

Displays a summary of the FIB

Router#show ip cef unresolved

Displays unresolved FIB entries

Router#show ip cef fastethernet 0/1

Displays the FIB entry for the specified interface

Router#show ip cef fastethernet 0/1 detail

Displays detailed information about the FIB for the interface

Router#show cef drop

Displays packets that are dropped due to adjacencies that are incomplete or nonexistent

Troubleshooting CEF

Router#debug ip cef

Displays debug information for CEF

Router#debug ip cef drop

Displays debug information about dropped packets

Router#debug ip cef access-list x

Displays information from specified access lists

Router#debug ip cef receive

Displays information about packets received by IP CEF

Router#debug ip cef events

Displays general CEF events

Router#debug ip cef prefix-ipc

Displays updates related to IP prefix information

Router#debug ip cef table

Produces a table showing events related to the FIB table

2. Configuring MPLS on a Frame Mode Interface | Next Section