Huawei NetEngine80E Configuration Manual - Reliability page 256

HUAWEI NetEngine80E/40E Router
Configuration Guide - Reliability
A BFD session dynamically triggered by a routing protocol is implemented as follows:
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After a routing protocol-specific neighbor relationship is established successfully, a routing
protocol triggers the establishment of a BFD session by using a routing management module
and the BFD session rapidly checks the protocol-specific neighbor relationship. Detection
parameters of BFD sessions are configured by a routing protocol.
If a BFD session detects a failure, the session goes Down, and BFD triggers route convergence
through a routing management module.
If a neighbor is unreachable, a routing protocol instructs BFD to delete the session by through
a routing management module.
BFD for Fast Reroute
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BFD for IS-IS
On the NE80E/40E, a static BFD session is used to check the IS-IS neighbor relationship.
BFD detects a link fault between IS-IS neighbors, and rapidly reports it to IS-IS to trigger IS-
IS convergence rapidly.
BFD for LSP
BFD detects failures in an MPLS LSP forwarding path on the data plane. As the format of BFD
packets is unchanged, the BFD packets are easily transmitted through hardware and traverse
through firewalls. The advantages of BFD for LDP LSP on the data plane are as follows:
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Issue 02 (2011-09-10)
Dynamically allocating the local discriminator
Self-learning the remote discriminator
NOTE
A routing protocol implements second-level detection by using Hello messages based on the keepalive
mechanism, and BFD implements millisecond-level detection at intervals of 10 milliseconds with the
detection multiplier being 3. BFD advertises a protocol failure within 50 milliseconds, which speeds up
route convergence.
BFD for LDP FRR
MPLS uses software for forwarding. BFD detects faults in the protected interfaces. LDP
FRR switchover is triggered if a BFD session is Down.
BFD for IP FRR and BFD for VPN FRR
On NE80E/40Es, IP FRR and VPN FRR switchovers are triggered only after detected faults
are reported to the control plane.
BFD provides reliability for MPLS-based applications, such as VPN FRR, TE FRR, and
VLL FRR, to protect services.
NOTE
l As IS-IS sets up only single-hop IS-IS adjacencies, BFD is applicable only to single-hop IS-IS
adjacencies.
l For the detailed configuration of BFD for IS-IS, refer to the chapter "IS-IS Configuration" in the
HUAWEI NetEngine80E/40E Router Configuration Guide - IP Routing.
Only reachable IP routes are required for a backward link.
Supports rapid detection.
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