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CX11x, CX31x, CX710 (Earlier Than V6.03), and CX91x Series Switch Modules V100R001C10 Configuration Guide 12

The documents describe the configuration of various services supported by the CX11x&CX31x&CX91x series switch modules The description covers configuration examples and function configurations.
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Introduction to BFD

Introduction to BFD

This section describes the definition and functions of BFD.


Bidirectional Forwarding Detection (BFD) is a unified detection mechanism used to rapidly detect link faults and monitor IP connectivity.


A network device must detect a communications fault between adjacent devices quickly so that the upper layer protocol can rectify the fault and prevent a service interruption. In practice, hardware detection is used to detect link faults. For example, Synchronous Digital Hierarchy (SDH) alarms are used to report link faults. However, not all media can provide the hardware detection mechanism. Applications use the Hello mechanism of the upper-layer routing protocol to detect faults. The detection duration is more than 1 second, which is too long for some applications. If no routing protocol is deployed on a small-scale Layer 3 network, the Hello mechanism cannot be used.

BFD provides fast fault detection independent of media and routing protocols. It has the following advantages:

  • Rapidly detects link faults between neighboring network devices. The detected faults may occur on interfaces, data links, or forwarding engines.

  • Provides uniform detection for all media and protocol layers in real time.


BFD rapidly detects link faults and monitors IP connectivity, helping you improve network performance. Adjacent systems can quickly detect communication faults so that a standby channel can be created immediately to restore communication and ensure network reliability.

Updated: 2019-08-09

Document ID: EDOC1000041694

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