How Bfd Works - H3C S3610-28P Operation Manual

Operation Manual – BFD-GR
H3C S3610&S5510 Series Ethernet Switches
Chapter 1 BFD Configuration
When configuring BFD, go to these sections for information you are interested in:
Introduction to BFD
BFD Configuration Task List
Displaying and Maintaining BFD
Note:
The term "router" or router icon in this document refers to a router in a generic sense or
an Ethernet switch running routing protocols.
1.1 Introduction to BFD
Bidirectional forwarding detection (BFD) provides a consistent mechanism to quickly
detect and monitor the connectivity of links or IP forwarding paths in networks. To
improve network performance, protocols on adjacent devices must quickly detect
communication failures to restore the communication through backup paths as soon as
possible. Normally, a network employs the following detection methods:
Quickly detecting link failures by sending hardware detection signals, such as
SDH (synchronous digital hierarchy) transmission system alarms.
If no hardware detection signals are provided or failures cannot be detected
through hardware detection signals, the network uses the hello mechanism of a
routing protocol for failure detection, which has a slower failure detection rate of
more than one second. In Gigabit data transmission, such a rate will cause a large
quantity of data to be dropped.
Implementing real-time detection for all media types and protocols through a
uniform mechanism and providing different detection intervals and costs.

1.1.1 How BFD Works

BFD provides a general-purpose, standard, medium- and protocol-independent fast
failure detection mechanism. It can uniformly and quickly detect the failures of the
bidirectional forwarding paths between two routers for upper-layer protocols, such as
routing protocols and Multiprotocol Label Switching (MPLS).
BFD establishes sessions between two routers to monitor the bidirectional forwarding
paths in between providing services for upper-layer protocols. BFD provides no
neighbor discovery mechanism. Upper-layer protocols that BFD services notify BFD of
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Chapter 1 BFD Configuration