Bidirectional Forwarding Detection (BFD)


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KHNOG Micro-Event March 2016
Mr. Makara Meourn

Published in: Technology
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Bidirectional Forwarding Detection (BFD)

  1. 1. Makara Moeurn ECS Value (Cambodia) Co., LTD 095 692265
  2. 2. BFD Protocol Overview BFD in Action BFD Study case Cisco Router Configuration and Demo
  3. 3. Ø BFD is a protocol that provides a low-overhead, short-duration method of detecting failures in the forwarding path between two adjacent routers, including the interfaces, data links, and forwarding planes. Ø Once detecting a failure, triggers an action in a routing protocol Ø There are 2 BFD modes: Asynchronous : periodically send control packet between peers Demand : send control packet when needed
  4. 4. Two types of hello packet Ø BFD control packet : each peer needs to process the packet Ø Echo packet : when one peer receive echo packet, it just loop back the echo to the same link without processing packet
  5. 5. Ø ON Distributed Routing Platforms - a) BFD packets processed at Line card. b) Hello packets of Routing protocol processed at RP CPU.
  6. 6. ØBFD provides fast BFD peer failure detection times independently of all media types, encapsulations, topologies, and routing protocols OSPF, BGP, HSRP, MPLS LSP, etc. ØSome vendor product can support static route binding and layer 2 link detection.
  7. 7. ØBy sending rapid failure detection notices to the routing protocols in the local router to initiate the routing table recalculation process, BFD contributes to greatly reduced overall network convergence time
  8. 8. ØBFD session 3-way handshake and tear down process ØOne BFD session for multiple client protocols or applications.
  9. 9. Ø Two routers are connected to each other across the long distance that have a lot of devices such as switches, transmission devices etc. Ø When one link down in the middle, the routers can’t know the link failure immediately, and wait till the dead time interval of the routing protocol Ø If not using routing protocol, then both router won’t know the link failure between them at all
  10. 10. Two Step for configuring BFD on Cisco Router ØStep1: BFD Interface level configuration Router(config-if)# bfd interval 50 min_rx 50 multiplier 5 ØStep2: BFD Routing Protocol Level configuration Router(config)# router ospf 1 Router(config-router)# bfd all-interfaces