BFD is a unified detection mechanism used to quickly detect link faults and monitor IP connectivity.
To minimize the impact of device faults on services and improve network availability, a network device must be able to quickly detect faults in communication with adjacent devices. Measures can then be taken to promptly rectify the faults to ensure service continuity. 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. On a Layer 3 network, the Hello packet detection mechanism cannot detect faults for all routes, such as static routes. This means that a fault between interconnected systems is difficult to locate.
BFD addresses these issues and provides fast fault detection independent of media and routing protocols. BFD is useful because it can:
Quickly detect link faults between neighboring network devices. The detected faults may occur on interfaces, data links, or forwarding engines.
Provide uniform detection for all media and protocol layers in real time.
With BFD, you can improve network performance and adjacent systems can quickly detect communication faults so that a standby channel can be created immediately to restore communications and ensure network reliability.