Juniper JUNOSE 11.0.X IP SERVICES, Configuration Manual

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Chapter 4
Configuring BFD
This chapter describes how to configure bidirectional forwarding detection (BFD) on
your E-series router; it contains the following sections:
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Bidirectional Forwarding Detection Overview on page 113
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BFD Platform Considerations on page 116
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BFD References on page 116
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Configuring a BFD License on page 117
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BFD Version Support on page 117
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Configuring BFD on page 118
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Managing BFD Adaptive Timer Intervals on page 118
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Clearing BFD Sessions on page 119
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Monitoring BFD on page 120
Bidirectional Forwarding Detection Overview
Fast failure detection is a high priority feature for any network element. Some media,
like Ethernet, do not provide remote end failure. Networks must often rely on internal
gateway protocol (IGP) hello messages to detect any failure and, in some cases (for
example, static routes), even these hello messages are not used.
IGP hellos have their own limitations—it often takes one second or more to detect
a remote end failure and processing IGP hello messages takes precious processing
time. BFD overcomes IGP detection time and processing limitations in detecting any
data path failures.
When configured for protocols like OSPF and IS-IS, BFD employs rapid, periodic,
and inexpensive hello messages to detect path activity. You can also configure BFD
to function with static routes, combining with the BFD poll bit to detect path activity.
When configured for various protocols like OSPF and IS-IS, BFD employs rapid,
periodic and inexpensive hello messages to detect path activity. You can also configure
BFD to function with static routes, combining with the BFD poll bit to detect path
activity.
You can also configure a BFD session with a BGP neighbor or peer group to determine
relatively quickly whether the neighbor or peer group is reachable. For information
Bidirectional Forwarding Detection Overview
■ 113