Introduction; Bfd Overview; Bfd Features Supported By The Ne80E/40E - Huawei NetEngine80E Configuration Manual - Reliability

HUAWEI NetEngine80E/40E Router
Configuration Guide - Reliability

5.1 Introduction

BFD rapidly detects communication faults between a local device and its neighbors. This
minimizes the impact of the faults on services.

5.1.1 BFD Overview

BFD is a uniform detection mechanism for an entire network. It detects faults quickly and
monitors the forwarding and connectivity of links or IP routes of the network.
On a network, a link fault is detected in either of the following methods:
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The following problems exist in the preceding methods:
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BFD is developed to resolve these problems.
BFD provides the following functions:
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5.1.2 BFD Features Supported by the NE80E/40E

The NE80E/40E supports BFD sessions establishment modes, two detection modes (single-hop
BFD and multi-hop BFD), BFD passive Echo function, association between the BFD session
status and the interface status, dynamic modification of parameters, binding a BFD session to a
VPN instance.
BFD is a unified detection mechanism used by multiple protocols.
This section briefly describes applications provided by BFD.
BFD Session Establishment Supported by the NE80E/40E
BFD uses local and remote discriminators to differentiate multiple BFD sessions between a pair
of systems. The local and remote discriminators are set in various modes. Based on these modes,
the following types of BFD sessions are supported by the NE80E/40E:
Issue 02 (2014-09-30)
Hardware detection signals, such as those provided by the Synchronous Digital Hierarchy
(SDH) alarm function, are used to detect a link fault rapidly.
If the hardware detection method is unavailable, the Hello mechanism of a routing protocol
is used to detect faults.
Hardware is used by only part of mediums to detect faults.
The routing protocol-specific Hello mechanism takes more than 1 second to detect a fault.
If data is forwarded at gigabit rates, a large amount of data is dropped.
On a small-scale Layer 3 network, if no routing protocol is deployed, the routing protocol-
specific Hello mechanism does not detect faults. This means that a fault between
interconnected systems is difficult to locate.
Detects faults rapidly along paths between neighboring forwarding engines, with light loads
and high speeds.
Uses a single mechanism to monitor any kind of medium and protocol layer in real time.
Detection time and costs vary.
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