IPv6 Switching: Cisco Express Forwarding Support

The Cisco Express Forwarding feature is Layer 3 IP switching technology for the forwarding of IPv6 packets.

Prerequisites for IPv6 Switching: Cisco Express Forwarding

  • To forward IPv6 traffic using Cisco Express Forwarding , you must configure forwarding of IPv6 unicast datagrams globally on the device, and you must configure an IPv6 address on an interface.

  • You must enable Cisco Express Forwarding for IPv4 globally on the device before enabling Cisco Express Forwarding for IPv6 globally on the device.

  • Nondistributed platforms do not support distributed Cisco Express Forwarding; however, some distributed platforms support both Cisco Express Forwarding and distributed Cisco Express Forwarding.

  • To use Unicast Reverse Path Forwarding (uRPF), enable Cisco Express Forwarding switching in the device. There is no need to configure the input interface for Cisco Express Forwarding switching. As long as Cisco Express Forwarding is running on the device, individual interfaces can be configured with other switching modes.

The following restrictions apply to nondistributed and distributed architecture platforms configured for Cisco Express Forwarding :

  • IPv6 packets that have global source and destination addresses are Cisco Express Forwarding-switched .

  • IPv6 packets that have link-local source and destination addresses are process-switched.

  • IPv6 packets that are tunneled within manually configured IPv6 tunnels are Cisco Express Forwarding-switched.

Information About IPv6 Switching: Cisco Express Forwarding Support

Cisco Express Forwarding for IPv6

Cisco Express Forwarding is advanced, Layer 3 IP switching technology for the forwarding of IPv6 packets.

Each IPv6 router interface has an association to one IPv6 global FIB and one IPv6 link-local FIB (multiple interfaces can have an association to the same FIB). All IPv6 router interfaces that are attached to the same IPv6 link share the same IPv6 link-local FIB. IPv6 packets that have an IPv6 global destination address are processed by the IPv6 global FIB; however, packets that have an IPv6 global destination address and an IPv6 link-local source address are sent to the RP for process switching and scope-error handling. Packets that have a link-local source address are not forwarded off of the local link and are sent to the RP for process switching and scope-error handling.

How to Configure IPv6 Switching: Cisco Express Forwarding Support

Configuring Cisco Express Forwarding

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    Do the following:

    • ipv6 cef

    4.    ipv6 cef accounting [non-recursive | per-prefix | prefix-length]


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example: 
    Device> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     
    Step 2 configure terminal


    Example: 
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3Do the following:
    • ipv6 cef


    Example: 
    Device(config)# ipv6 cef
     

    Enables Cisco Express Forwarding globally on the device.

     
    Step 4 ipv6 cef accounting [non-recursive | per-prefix | prefix-length]


    Example: 
    Device(config)# ipv6 cef accounting
     

    Enables Cisco Express Forwarding network accounting globally on the device.

    • Network accounting for Cisco Express Forwarding enables you to better understand Cisco Express Forwarding traffic patterns within your network by collecting statistics specific to Cisco Express Forwarding traffic. For example, network accounting for Cisco Express Forwarding enables you to collect information such as the number of packets and bytes switched to a destination or the number of packets switched through a destination.

    • The optional per-prefix keyword enables the collection of the number of packets and bytes express forwarded to an IPv6 destination (or IPv6 prefix).

    • The optional prefix-length keyword enables the collection of the number of packets and bytes express forwarded to an IPv6 prefix length.

    Note   

    When Cisco Express Forwarding is enabled globally on the device, accounting information is collected at the RP.

     

    Configuration Examples for IPv6 Switching: Cisco Express Forwarding Support

    Example: Cisco Express Forwarding Configuration

    In the following example, both Cisco Express Forwarding for IPv6 and network accounting for Cisco Express Forwarding for IPv6 have been enabled globally on a nondistributed architecture device, and Cisco Express Forwarding for IPv6 has been enabled on Gigabit Ethernet interface 0/0/0. The example also shows that the forwarding of IPv6 unicast datagrams has been configured globally on the device with the ipv6 unicast-routing command, an IPv6 address has been configured on Gigabit Ethernet interface 0/0/0 with the ipv6 address command, and Cisco Express Forwarding for IPv4 has been configured globally on the device with the ip cef command. 

    ip cef
ipv6 unicast-routing
ipv6 cef
ipv6 cef accounting prefix-length
interface gigabitethernet0/0/0
 ip address 10.4.9.11 255.0.0.0
 media-type 10BaseT
 ipv6 address 2001:DB8:C18:1::/64 eui-64

    Additional References

    Related Documents

    Related Topic

    Document Title

    Cisco Express Forwarding for IPv6

    Implementing IPv6 Addressing and Basic Connectivity Guide, IPv6 Configuration Guide

    Cisco IOS voice configuration

    Cisco IOS Voice Configuration Library

    Cisco IOS commands

    Cisco IOS Master Commands List, All Releases

    IPv6 commands, including voice commands

    Cisco IOS IPv6 Command Reference

    Cisco Unified Border Element configuration

    Cisco Unified Border Element Configuration Guide

    SIP Configuration Guide

    SIP Configuration Guide

    Troubleshooting and debugging guides

    Cisco IOS Debug Command Reference

    Troubleshooting and Debugging VoIP Call Basics

    MIBs

    MIB

    MIBs Link

    No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

    To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

    http:/​/​www.cisco.com/​go/​mibs

    Technical Assistance

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    The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

    http:/​/​www.cisco.com/​cisco/​web/​support/​index.html