The isis timer ldp-sync hold-down command sets the interval during which an interface waits for creating an LDP session before setting up an IS-IS neighbor relationship.
The undo isis timer ldp-sync hold-down command restores the default interval.
By default, the interval is 10 seconds.
| Parameter | Description | Value |
|---|---|---|
| value | Specifies the interval during which an interface waits for creating an LDP session before setting up the IS-IS neighbor relationship. | An integer ranging from 0 to 65535, in seconds. The default value 10 (in seconds) is recommended. |
Ethernet interface view, Ethernet sub-interface view, Eth-Trunk interface view, Eth-Trunk sub-interface view, Tunnel interface view, Loopback interface view, Dialer interface view, VLANIF interface view, Virtual-Template interface view
Usage Scenario
On a network with both active and standby links, if the active link fails, traffic switches to a standby link. Therefore, the standby IS-IS route and backup LDP label switched path (LSP) along the standby link become reachable. After the active link recovers, its IS-IS route converges more rapidly than the LDP LSP. As a result, the IS-IS neighbor relationship is established earlier than the LDP session on the active link. Although traffic is directed over the IS-IS route to the active link, traffic fails to be forwarded because no LDP LSP is established.
To prevent the traffic forwarding failure, LDP and IS-IS synchronization can be configured. After the active link recovers from a physical fault, the IS-IS route for the active link is set to the Hold-down state, and the Hold-down timer starts. After an LDP session is established over the active link or the Hold-down timer expires, the IS-IS neighbor relationship starts to be established. This allows the LDP LSP and IS-IS route to go Up simultaneously. To set the Hold-down timer, run the isis timer ldp-sync hold-down command.
Prerequisites
An IS-IS process has been enabled using the isis enable command in the interface view.
# Set the interval to 15 seconds, during which an interface waits for creating an LDP session before setting up the IS-IS neighbor relationship.
<sysname> system-view
[sysname] interface GigabitEthernet 0/0/0 [sysname-GigabitEthernet0/0/0] isis enable 1 [sysname-GigabitEthernet0/0/0] isis timer ldp-sync hold-down 15