Routing Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Release

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Guidelines for implementing BFD

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Describes ACL, port, and ICMPv6 considerations that affect BFD session establishment and operation for BGP environments.


  • UMPP and LPTS ACLs apply only while a BFD session is being established and the remote discriminator is 0.

  • After the session is established, BFD is offloaded to hardware, and control packets bypass UMPP ACL processing.

  • Changes to UMPP ACLs after session establishment do not affect active BFD sessions.

  • Use these UDP ports:

    • 3784 for single-hop BFD

    • 4784 for multihop BFD

    • 6784 for IETF BFD over bundle

  • For IPv6 control-plane reachability, permit ICMPv6 if the ACL contains an implicit deny rule.