The isis delay-peer command configures a delay for an interface so that the interface delays establishing neighbor relationships after the neighbor relationship with the last neighbor goes Down due to packet timeout.
The undo isis delay-peer command deletes the configured delay and restores the default configurations.
By default, if the neighbor relationship goes Down due to packet timeout, the interface re-establishes the neighbor relationship after it receives a new Hello packet.
isis delay-peer track last-peer-expired [ delay-time delay-interval ]
undo isis delay-peer [ track last-peer-expired [ delay-time delay-interval ] ]
| Parameter | Description | Value |
|---|---|---|
| track | Tracks the mode of the neighbor relationship establishment delay. | - |
| last-peer-expired | Indicates that neighbor relationship establishment is delayed after the neighbor relationship with the last neighbor goes Down due to packet timeout. | - |
| delay-time delay-interval | Specifies the neighbor relationship establishment delay. | The value is an integer ranging from 1 to 3600, in seconds. The default value is 60 seconds. |
Usage Scenario
On IS-IS networks, devices at both ends of a link establish a neighbor relationship by exchanging Hello packets. After the neighbor relationship is established, both devices need to send Hello packets at a specified interval to maintain the neighbor relationship. If an IS-IS device does not receive any Hello packets from the neighbor at the other end within the specified period (Holddown time), the local device considers the neighbor Down and re-establishes the neighbor relationship after it receives a new Hello packet. If links are unstable or some Hello packets are lost or incorrect due to network transmission delay or poor transmission, neighbor relationships may alternate between Up and Down frequently, which causes a route flapping.
To address this issue, run the isis delay-peer command to configure a neighbor relationship establishment delay after the neighbor relationship goes Down.
Pre-configuration Tasks
IS-IS has been enabled using the isis enable command in the interface view.
Precautions
If a new delay-interval is configured and it is less than the remaining time of the ongoing delay, the new delay-interval takes effect immediately; if the new delay-interval is greater than the remaining time of the ongoing delay, the ongoing delay continues until the new delay-interval takes effect at the next delay.
# Set the delay to 100s on VLANIF100 so that the neighbor relationship establishment is delayed after the neighbor relationship with the last neighbor goes Down due to packet timeout.
<HUAWEI> system-view [HUAWEI] isis [HUAWEI-isis-1] network-entity 01.0000.0000.0001.00 [HUAWEI-isis-1] quit [HUAWEI] interface vlanif 100 [HUAWEI-Vlanif100] isis enable 1 [HUAWEI-Vlanif100] isis delay-peer track last-peer-expired delay-time 100
# Set the delay to 100s on GE0/0/1 so that the neighbor relationship establishment is delayed after the neighbor relationship with the last neighbor goes Down due to packet timeout.
<HUAWEI> system-view [HUAWEI] isis [HUAWEI-isis-1] network-entity 01.0000.0000.0001.00 [HUAWEI-isis-1] quit [HUAWEI] interface gigabitethernet 0/0/1 [HUAWEI-GigabitEthernet0/0/1] undo portswitch [HUAWEI-GigabitEthernet0/0/1] isis enable 1 [HUAWEI-GigabitEthernet0/0/1] isis delay-peer track last-peer-expired delay-time 100