Dell N3200-ON EMC Networking N-Series Switches User Guide version 6.6.3 - Page 1465

39 Bidirectional Forwarding Detection Dell EMC Networking N3000E-ON, N3100-ON, and N3200-ON Series Switches NOTE: This feature is not available on Dell EMC Networking N1100-ON, N1500, N2000, N2100-ON and N2200X-ON Series switches. Bidirectional Forwarding Detection (BFD) provides a lightweight fast failure detection mechanism to verify bidirectional connectivity between forwarding engines, which may be a single hop or multiple hops away from each other. The topics covered in this chapter include: • Overview • BFD Operational Modes • Limitations • BFD Example Overview BFD only supports notification of failures to the BGP and OSPF protocols. The BFD protocol is designed to work over any underlying transmission mechanism and protocol layer with a wide range of detection times, especially in scenarios where fast failure detection is required in the data plane level for multiple concurrent sessions. For example, the BGP keepalive timer is 60 seconds and the hold timer is 180 seconds. A typical BFD session might use a 200-millisecond min_rx interval with a multiplier of 5. This means that BGP would detect a connectivity failure in 180 seconds, whereas BFD would report the same failure in slightly more than one second. In Dell EMC Networking N-Series switches, BFD is presented as a service that reports on the session status to its client applications. BFD uses a simple 'hello' mechanism that is similar to the neighbor detection components of some well-known protocols. It establishes an operational session between a pair of network devices to verify a two-way communication path between them and serves information regarding the connectivity status Bidirectional Forwarding Detection 1465