IP Routing: BGP Configuration Guide, Cisco IOS XE Release 3S
eiBGP Multipath for Non-VRF Interfaces (IPv4/IPv6)
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eiBGP Multipath for Non-VRF Interfaces (IPv4/IPv6)

eiBGP Multipath for Non-VRF Interfaces (IPv4/IPv6)

The eiBGP Multipath for Non-VRF Interfaces (IPv4/IPv6) feature allows you to configure multipath load sharing among native IPv4 and IPv6 external Border Gateway Protocol (eBGP) and internal BGP (iBGP) paths for improved load balancing in deployments. This module explains the feature and how to configure it.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

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.

Information About eiBGP Multipath for Non-VRF Interfaces (IPv4/IPv6)

eiBGP Multipath for Non-VRF Interfaces Overview

The Border Gateway Protocol (BGP) path-selection algorithm prefers external BGP (eBGP) paths over internal BGP (iBGP) paths. With the eiBGP Multipath for Non-VRF Interfaces (IPv4/IPv6) feature, this algorithm is modified to allow multipath load sharing among native IPv4 and IPv6 eBGP and iBGP paths. Prior to the eiBGP Multipath for Non-VRF Interfaces (IPv4/IPv6) feature, this functionality was only available on VPN routing and forwarding (VRF) instances. With this feature, the functionality is extended to non-VRF interfaces. The maximum-paths command allows you to configure BGP to install multiple paths in the Routing Information Base (RIB) for multipath load sharing. The BGP best path algorithm selects a single multipath as the best path and advertises the path to BGP peers. Other multipaths are inserted into both the BGP table and the RIB, and these multipaths are used by Cisco Express Forwarding to perform load balancing, which is performed either on a per-packet basis or on a per-source or per-destination basis.

This feature can be configured on a customer provider edge (PE) device. However, the feature should be configured only on one PE device at the customer site. If this feature is configured on more than one PE device, some parts of the traffic may loop between the PE devices at the customer site. Therefore, it is important to set up the feature appropriately to avoid traffic loops. This feature is enabled by default.

How to Configure eiBGP Multipath for Non-VRF Interfaces (IPv4/IPv6)

Enabling IPv4/IPv6 Multipaths for Non-VRF Interfaces

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    router bgp autonomous-system-number

    4.    Enter one of the following:

    • address-family ipv4 unicast
    • address-family ipv6 unicast

    5.    maximum-paths eibgp number

    6.    end


DETAILED STEPS
     Command or ActionPurpose
    Step 1enable


    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 3 router bgp autonomous-system-number


    Example:
    Device(config)# router bgp 64496 
     

    Enters router configuration mode to create or configure a Border Gateway Protocol (BGP) routing process.

     
    Step 4Enter one of the following:
    • address-family ipv4 unicast
    • address-family ipv6 unicast


    Example:
    Device(config-router)# address-family ipv4 unicast
    Device(config-router)# address-family ipv6 unicast
     

    Enters IPv4 or IPv6 address family configuration mode.

     
    Step 5 maximum-paths eibgp number


    Example:
    Device(config-router-af)# maximum-paths eibgp 3
     

    Forwards packets over multiple external BGP (eBGP) and internal BGP (iBGP) paths.

     
    Step 6 end


    Example:
    Device(config-router-af)# end
     
    Exits address family configuration mode and returns to privileged EXEC mode.  

    Configuration Examples for eiBGP Multipath for Non-VRF Interfaces (IPv4/IPv6)

    Example: Enabling IPv4/IPv6 Multipaths in Non-VRF Interfaces

    The following example shows how to enable IPv4 multipaths on non-VRF interfaces.

    Device> enable
    Device# configure terminal
    Device(config)# router bgp 64496
    Device(config-router)# address-family ipv4 unicast
    Device(config-router-af)# maximum-paths eibgp 4
    Device(config-router-af)# end

    The following example shows how to enable IPv6 multipaths on non-VRF interfaces.

    Device> enable
    Device# configure terminal
    Device(config)# router bgp 64497
    Device(config-router)# address-family ipv6 unicast
    Device(config-router-af)# maximum-paths eibgp 4
    Device(config-router-af)# end

    Feature Information for eiBGP Multipath for Non-VRF Interfaces (IPv4/IPv6)

    The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. 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.

    Table 1 Feature Information for eiBGP Multipath for Non-VRF Interfaces (IPv4/IPv6)

    Feature Name

    Releases

    Feature Information

    eiBGP Multipath for Non-VRF Interfaces (IPv4/IPv6)

    The eiBGP Multipath for Non- VRF Interfaces (IPv4/IPv6) feature allows you to configure multipath load sharing among native IPv4 and IPv6 external Border Gateway Protocol (eBGP) and internal BGP (iBGP) paths for improved load balancing in deployments.

    The following command was modified: maximum-paths eibgp.