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Applicable Environment
As shown in
, RouterA and RouterB are connected on the same network segment. In
the middle of the physical link resides Layer 2 transmission devices, so the physical link is
divided into multiple segments. It takes a long period for the two devices on both ends of the
link to detect a link fault. The directly connected route spends al long time on becoming
ineffective, and network interruption lasts for a long period.
Figure 3-2
A transit device exists on the link
RouterA
RouterB
To speed up route convergence, associate the BFD status and interface status so that the BFD
session status change will trigger the protocol status change on the interface.
When BFD detects a fault, it enters the Down state, and then the bound interface also enters the
BFD_Down state. The direct route of the interface is deleted from the routing table; however,
the BFD packets are still forwarded.
NOTE
l
Before the BFD status is associated with the interface status, the BFD configurations on two routers
must be correct and matched. If the BFD status on the local interface is Down, check whether the BFD
configuration on the remote end is correct and the BFD session is shut down.
l
If the BFD session must be synchronized to an interface immediately, ensure that the BFD
configurations on the two routers are the same and run the
shutdown
and
undo shutdown
commands
on the BFD session. When the
undo shutdown
command is executed for a BFD session, a BFD session
detection timer is started. If the BFD session becomes Up through negotiation before the timer times
out, the BFD session notifies an interface of the Up state. Otherwise, the BFD session considers the
link faulty and notifies the interface of the Down state. The status of a BFD session and the status of
an interface are synchronized in real time.
Pre-Configuration Tasks
Before associating BFD status with interface status, complete the following task:
l
Connecting interfaces properly
Procedure
Step 1
Run:
system-view
The system view is displayed.
Step 2
Run:
bfd
BFD is globally enabled and the BFD view is displayed.
Step 3
Run:
default-ip-address
ip-address
Huawei AR2200-S Series Enterprise Routers
Configuration Guide - Reliability
3 BFD Configuration
Issue 01 (2012-01-06)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
165