The isis timer ldp-sync hold-max-cost command sets the interval during which IS-IS sends LSPs to advertise the maximum metric on the local device.
The undo isis timer ldp-sync hold-max-cost command restores the default interval.
By default, the interval is 10 seconds.
isis timer ldp-sync hold-max-cost { value | infinite }
undo isis timer ldp-sync hold-max-cost
| Parameter | Description | Value |
|---|---|---|
| value | Specifies the interval during which IS-IS sends LSPs to advertise the maximum metric on the local device. | An integer ranging from 0 to 65535, in seconds |
| infinite | Indicates that IS-IS keeps advertising the maximum metric in LSPs on the local device before an LDP session is reestablished. | - |
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 active and standby links, when the IS-IS route of the active link is reachable and an LDP session between two nodes on the active link fails, traffic is transmitted over the IS-IS route of the active link, whereas the label switched path (LSP) on the active link fails. Although LSP traffic attempts to be switched to the backup LSP, the active IS-IS route is selected to direct traffic. As a result, traffic on the primary LSP is lost.
To prevent the traffic forwarding failure, LDP and IS-IS synchronization can be configured. If the LDP session over the active link fails, IS-IS advertises the maximum cost of the active link route. The IS-IS route for the standby link is selected, and the Hold-max-cost timer starts. After the LDP LSP over the standby link is established, and the IS-IS route for the standby link is reachable, traffic switches to the standby link. After the LDP session on the active link recovers or the Hold-max-cost timer expires, IS-IS advertises the actual cost of the active link route. To set the Hold-max-cost timer, run the isis timer ldp-sync hold-max-cost command.
When IS-IS carries LDP services only, configure infinite to keep the IS-IS route and LSP over the same link.
If IS-IS carries multiple types of services including LDP services in the networking, configure value to ensure that interruption of an LDP session over the active link does not affect IS-IS routing and other services. The default is 10, in seconds, which is a recommended value.
Prerequisites
An IS-IS process has been enabled using the isis enable command in the interface view.