(Optional) Setting the Hold-max-cost Timer Value

This section describes how to set the hold-max-cost timer. The timer is an interval for advertising the maximum cost using LSAs generated locally.

Context

If an LDP session over the active link fails but an IGP route for the active link is reachable, a node that has LDP-IGP synchronization enabled uses a Hold-max-cost timer to enable an IGP to advertise LSAs or LSPs carrying the maximum route cost, which delays IGP route convergence until an LDP session is established. Therefore, an IGP route for a standby link and an LDP session over the standby link can become available simultaneously.

If IS-IS is used, you can set the value of the hold-max-cost timer on a specified interface or set the value of the hold-max-cost timer for all IS-IS interfaces in the IS-IS view.

If different Hold-max-cost values on an interface and in an IS-IS process are set, the setting on the interface takes effect.

Procedure

If OSPF is used as an IGP, perform the following steps on an interface:
1. Access the system view.
```
system-view
```
2. Access the interface view.
```
interface interface-type interface-number
```
3. Set the Hold-max-cost timer to enable OSPF to keep advertising LSAs carrying the maximum route cost.
```
ospf timer ldp-sync hold-max-cost { value | infinite }
```
  The default Hold-max-cost time is 10s.
  Either of the following parameters can be configured in this command:
  - infinite: indicates that an OSPF interface keeps advertising LSAs carrying the maximum cost value until an LDP session is established. This parameter ensures that the OSPF route selects the same path over which an LDP LSP is established when an OSPF network carries only LDP services.
  - value: specifies the period of time during which an OSPF interface keeps advertising LSAs carrying the maximum cost value. This parameter helps prevent an LDP session disconnection from affecting OSPF routing or non-LDP services when an OSPF network carries multiple types of services, including LDP services.
  If the ospf timer ldp-sync hold-max-cost command is run more than once, the latest configuration overrides the previous one.
If IS-IS is used as an IGP, perform the following steps:
Set the Hold-max-cost timer on a specified IS-IS interface.
1. Access the system view.
```
system-view
```
2. Access the interface view.
```
interface interface-type interface-number
```
3. Set the Hold-max-cost timer to enable IS-IS to keep advertising LSPs carrying the maximum route cost.
```
isis timer ldp-sync hold-max-cost { value | infinite }
```
  The default Hold-max-cost time is 10s.
  Either of the following parameters can be configured in this command:
  - infinite: indicates that an IS-IS interface keeps advertising LSPs carrying the maximum cost value until an LDP session is established. This parameter ensures that the IS-IS route selects the same path over which an LDP LSP is established when an IS-IS network carries only LDP services.
  - value: specifies the period of time during which an IS-IS interface keeps advertising LSPs carrying the maximum cost value. This parameter helps prevent an LDP session disconnection from affecting IS-IS routing or non-LDP services when an IS-IS network carries various services, including LDP services.
  If the isis timer ldp-sync hold-max-cost command is run more than once, the latest configuration overrides the previous one.
Set the Hold-max-cost timer on all IS-IS interfaces in a specified IS-IS process.
1. Access the system view.
```
system-view
```
2. Access the IS-IS process view.
```
isis [ process-id ]
```
3. Set the Hold-max-cost timer to enable IS-IS to keep advertising LSPs carrying the maximum route cost on all interfaces within an IS-IS process.
```
timer ldp-sync hold-max-cost { infinite | interval }
```
  The default Hold-max-cost time is 10s.
  
  If different Hold-max-cost values on an interface and in an IS-IS process are set, the setting on the interface takes effect.