Users Guide

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Bidirectional Forwarding Detection 1465
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Bidirectional Forwarding Detection
Dell EMC Networking N3000E-ON, N3100-ON, and N3200-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
NOTE: This feature is not available on Dell EMC Networking N1100-ON, N1500,
N2000, N2100-ON and N2200X-ON Series switches.