–
If the
always
parameter is specified, the ATT bit is set to 1. After receiving the
LSPs carrying the ATT bit 1, the Level-1 router generates a default route.
–
If the
never
parameter is specified, the ATT bit is set to 0. After receiving the
LSPs carrying the ATT bit 0, the Level-1 router does not generate a default
route, which reduces the size of a routing table.
–
To disable the Level-1 router from generating default routes even though it receives
the LSPs carrying ATT bit 1, run the
attached-bit avoid-learning
command.
----End
7.4.7 Configuring an IPv4 IS-IS Interface to Automatically Adjust
the Link Cost
Configuring an IS-IS interface to automatically adjust the link cost based on link quality
facilitates route selection control and improves network reliability.
Context
A bit error refers to the deviation between a bit that is sent and the bit that is received. The bit
error rate (BER) refers to the number of bit errors divided by the total number of bits transferred
during a studied time interval. During data transmission, a high BER will degrade or even
interrupt services in extreme cases.
To prevent this problem, configure IS-IS interfaces to automatically adjust link costs based on
link quality, so that unreliable links are not used by the optimal routes.
Procedure
Step 1
Run:
system-view
The system view is displayed.
Step 2
Run:
interface
interface-type
interface-number
The interface view is displayed.
Step 3
Run:
isis enable
[
process-id
]
IS-IS is enabled on the interface.
Step 4
Run:
link-quality
low
bit-error-threshold
error-ratio
trigger-coefficient
trigger-power
resume-ratio
recovery-coefficient
recovery-power
The upper and lower thresholds for triggering link quality changes are set on the IS-IS interface.
After you run this command, if the BER of the IS-IS interface reaches or exceeds the upper
threshold, the link quality changes from good to low; if the BER of the IS-IS interface reaches
or falls below the lower threshold, the link quality changes from low to good.
Step 5
Run:
isis link-quality low incr-cost
{
cost
|
max-reachable
}
HUAWEI NetEngine80E/40E Router
Configuration Guide - IP Routing
7 IS-IS Configuration
Issue 02 (2014-09-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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