Cisco Catalyst 3850 Configuration Manual
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Cisco Catalyst 3850 Configuration Manual

Ip switching cisco express forwarding
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See also: Manual
IP Switching Cisco Express Forwarding
Configuration Guide, Cisco IOS XE
Release 3SE (Catalyst 3850 Switches)
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Summary of Contents for Cisco Catalyst 3850

  • Page 1 IP Switching Cisco Express Forwarding Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches) Americas Headquarters Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706 http://www.cisco.com Tel: 408 526-4000 800 553-NETS (6387) Fax: 408 527-0883...
  • Page 2 ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks.

  • Page 3: Table Of Contents

    CEF Distributed Tunnel Switching Links for the CEF Features How to Configure CEF Configuration Examples for CEF Additional References Feature Information for Cisco Express Forwarding IP Switching Cisco Express Forwarding Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches)
  • Page 4 Contents IP Switching Cisco Express Forwarding Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches)

  • Page 5: Cisco Express Forwarding

    Central CEF Mode Operation, page 6 • Distributed CEF Mode Operation, page 6 • CEF Features Enabled by Default, page 7 • Links for the CEF Features, page 8 IP Switching Cisco Express Forwarding Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches)

  • Page 6: Cisco Platform Support For Cef And Dcef

    Cisco Express Forwarding is enabled on a device, the route processor (RP) performs the express forwarding. To find out if Cisco Express Forwarding is enabled on your device, enter the show ip cef command. If Cisco Express Forwarding is enabled, you receive output that looks like this:...

  • Page 7: Media Supported By Cef

    Media Supported by CEF Information About CEF You can use Cisco Express Forwarding in any part of a network. For example, the figure below shows Cisco Express Forwarding being run on devices at aggregation points at the core of a network where traffic levels are high and performance is critical.

  • Page 8: Main Components Of Cef

    CEF FIB and Load Balancing Main Components of CEF Information conventionally stored in a route cache is stored in several data structures for Cisco Express Forwarding switching. The data structures provide optimized lookup for efficient packet forwarding. The two main components of Cisco Express Forwarding operation are the forwarding information base (FIB) and the adjacency tables.

  • Page 9: Adjacency Discovery

    CEF switching paths to the next higher switching level for handling. Discard adjacency The device discards the packets. Drop adjacency The device drops the packets. IP Switching Cisco Express Forwarding Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches)

  • Page 10: Unresolved Adjacency

    RP, and the adjacency is determined through ARP. Thus, the adjacency is resolved. Central CEF Mode Operation You can use central Cisco Express Forwarding mode when line cards are not available for Cisco Express Forwarding switching, when you need to use features not compatible with distributed Cisco Express Forwarding switching, or when you are running on a platform that is not a distributed platform.

  • Page 11: Cef Features Enabled By Default

    In the figure above, the line cards perform the switching. In devices where you can mix various types of cards in the same device, all line cards might not support distributed Cisco Express Forwarding. When a line card that does not support distributed Cisco Express Forwarding receives a packet from one of these other devices, the line card forwards the packet to the next higher switching layer (the RP).

  • Page 12: Cef Distributed Tunnel Switching

    Cisco Express Forwarding or distributed Cisco Express Forwarding. Links for the CEF Features The table below contains links to information about features that you can configure for use with Cisco Express Forwarding or distributed Cisco Express Forwarding operation. Table 2 Features to Configure for CEF or dCEF Operation For Information on This Feature...

  • Page 13: Configuration Examples For Cef

    Troubleshooting tips for incomplete adjacencies Troubleshooting Incomplete Adjacencies with CEF Information about troubleshooting Cisco Express Troubleshooting Cisco Express Forwarding Forwarding routing loops and suboptimal routing Routing Loops IP Switching Cisco Express Forwarding Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches)

  • Page 14: Feature Information For Cisco Express Forwarding

    Unless noted otherwise, subsequent releases of that software release train also support that feature. Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
  • Page 15 Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company.
  • Page 16 Links for the CEF Features IP Switching Cisco Express Forwarding Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches)

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