Huawei NetEngine80E Configuration Manual - Reliability page 252

HUAWEI NetEngine80E/40E Router
Configuration Guide - Reliability
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Discriminators of a dynamic BFD session triggered by a protocol are created as follows:
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The following conditions must be satisfied to allow two ends of a BFD session to create
discriminators in different modes:
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At present, one BFD session working as both a dynamic BFD session and a static BFD session
with automatically negotiated discriminators is supported by BFD for OSPF, BFD for IS-IS,
BFD for BGP, BFD for PIM, and BFD for RSVP-TE.
BFD Modes
The NE80E/40E supports the asynchronous mode.
Asynchronous mode:
Each system sends BFD Control packets at a negotiated interval. If a system does not receive
BFD Control packets from the peer within the detection time, it sets the session to Down.
Single-hop BFD and Multi-hop BFD
The NE80E/40E supports single-hop BFD and multi-hop BFD which check the reachability of
IP routes. This section describes single-hop BFD.
The NE80E/40E supports single-hop BFD for the following types of links:
Issue 02 (2011-09-10)
Static BFD sessions with manually specified discriminators
Static BFD sessions with automatically negotiated discriminators
Dynamic BFD sessions triggered by a protocol
Dynamically allocating the local discriminator
Self-learning the remote discriminator
NOTE
On the NE80E/40E, OSPF, BGP, IS-IS, MPLS, MPLS LDP, RSVP-TE, PWE3, and PIM dynamically
trigger the establishment of BFD sessions.
If a static BFD session is established by manually specifying the discriminators on one end,
the static BFD session on the other end must also be established by manually specifying
discriminators.
If a static BFD session is established by automatically negotiating the discriminators on
one end, the static BFD session on the other end is established by automatically negotiating
discriminators or a dynamic BFD session is established.
If both a static BFD session with automatically negotiated discriminators and a dynamic
BFD session are established on one end, the following principles are applicable:
– If these two sessions share the same configurations (the source address, destination
address, outgoing interface, and VPN index), one BFD session works as both the
dynamic BFD session and the static BFD session with automatically negotiated
discriminators.
– If the dynamic BFD session named DYN_local-discriminator is configured prior to the
static BFD session, the dynamic BFD session's name is replaced with the static BFD
session's name.
– Minimum values between these two sessions are used by the shared session.
NOTE
IP-Trunk cannot be configured on the X1 and X2 models of the NE80E/40E.
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5 BFD Configuration
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