Prerequisites for Implementing BFD
You must be in a user group associated with a task group that includes the proper task IDs. The command reference guides include the task IDs required for each command. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
The following prerequisites are required to implement BFD:
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If enabling BFD on Multiprotocol Label Switching (MPLS), an installed composite PIE file including the MPLS package, or a composite-package image is required. For Border Gateway Protocol (BGP), Intermediate System-to-Intermediate System (IS-IS), Static, and Open Shortest Path First (OSPF), an installed Cisco IOS XR IP Unicast Routing Core Bundle image is required.
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Interior Gateway Protocol (IGP) is activated on the router if you are using IS-IS or OSPF.
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On the Cisco ASR 9000 Series Router, each line card supporting BFD must be able to perform the following tasks:
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Send echo packets every 50ms * 3 (as a minimum under normal conditions)
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Send control packets every 150ms * 3 (as a minimum under stress conditions)
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Send and receive up to 9600 User Datagram Protocol (UDP) pps. This sustains 144 sessions at a 15-ms echo interval (or 1440 sessions at a 150-ms echo interval).
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To enable BFD for a neighbor, the neighbor router must support BFD.
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In Cisco IOS XR releases before Release 3.9.0, we recommended that you configure the local router ID with the router-id command in global configuration mode prior to setting up a BFD session. If you did not configure the local router ID, then by default the source address of the IP packet for BFD echo mode is the IP address of the output interface. Beginning in Cisco IOS XR release 3.9.0 and later, you can use the echo ipv4 source command to specify the IP address that you want to use as the source address.
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To support BFD on bundle member links, be sure that the following requirements are met:
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The routers on either end of the bundle are connected back-to-back without a Layer 2 switch in between.
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For a BFD session to start, any one of the following configurations or states are present on the bundle member:
Link Aggregation Control Protocol (LACP) Distributing state is reached, –Or–
EtherChannel or POS Channel is configured, –Or–
Hot Standby and LACP Collecting state is reached.
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