Configuring Synchronization Between LDP and Static Routes
Synchronization between LDP and static routes applies to MPLS networks where primary and backup LSPs exist. LSPs are established between LSRs based on static routes. When the LDP session on the primary LSP fails (not due to a link failure) or the faulty primary LSP is restored, you can enable synchronization between LDP and static routes to prevent traffic interruption caused by the active/standby switchover.
Pre-configuration Tasks
Before configuring synchronization between LDP and static routes, complete the following tasks:
Configuring a local LDP session according to Configuring Basic Functions of MPLS LDP
Context
Only the static route with a specified outbound interface can be configured with synchronization between LDP and static routes.
After a Hold-down timer is set on an interface, the static route enabled with synchronization between LDP and static routes becomes inactive temporarily and waits for an LDP session to be established before the Hold-down timer expires. This implements synchronization between LDP and static routes. If the Hold-down timer expires, the static route becomes active regardless of whether the LDP session has been established.
Perform the following steps on devices on both ends of the primary and backup links:
Procedure
- Run system-view
The system view is displayed.
- Run ip route-static ip-address { mask | mask-length } interface-type interface-number [ nexthop-address ] [ preference preference | tag tag ] * ldp-sync [ description text ]
Synchronization between LDP and static routes is configured.
By default, synchronization between LDP and static routes is disabled.
- (Optional) Configure a Hold-down Timer.
Run interface interface-type interface-number
The outbound interface view of the primary link of the static route is displayed.
Run static-route timer ldp-sync hold-down { timer | infinite }
The value of a Hold-down timer is set.
By default, the value of a Hold-down timer is set to 10 seconds.
If the value of the Hold-down timer is set to 0 seconds, synchronization between LDP and static routes is disabled on an interface.
If the value of the Hold-down timer is set to infinite, the timer never expires. In this case, the static route becomes active and MPLS traffic is switched only after an LDP session is established.
A Hold-down timer cannot be set on loopback interfaces, Layer 2 Ethernet interfaces, or null interfaces.
