[Cisco] How to Check CEF (Cisco Express Forwarding)

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Cisco Express Forwarding (CEF) is advanced Layer 3 IP switching technology. CEF optimizes network performance and scalability for networks with large and dynamic traffic patterns, such as the Internet, on networks characterized by intensive Web-based applications, or interactive sessions.

CEF offers these benefits:

• Improved performance
• Scalability
• Resilience

Although you can use CEF in any part of a network, it is designed for high-performance, highly resilient Layer 3 IP switching.

 

Cisco Router#sh cef linecard
CEF table version 251092, 1027 routes
Slot CEF-ver MsgSent XdrSent Seq MaxSeq LowQ MedQ HighQ Flags
1 251092 531724 555310 18901 18925 0 0 0 up, sync
2 251092 531724 555309 18901 18925 0 0 0 up, sync
4 251092 531724 555308 18901 18925 0 0 0 up, sync
5 251092 531724 555310 18901 18925 0 0 0 up, sync
7 251092 531724 555322 18901 18925 0 0 0 up, sync
Cisco Router#

– To restart CEF, try below command. After that, check memory so the router won’t crash

 

Cisco Router(config)#no ip cef distributed
Cisco Router(config)#ip cef distributed

 

Reference ; http://www.cisco.com/en/US/docs/ios/12_0/switch/configuration/guide/xccef.html