Configuring Bit-Error-Triggered RSVP-TE Tunnel Switching

This section describes how to configure bit-error-triggered Resource Reservation Protocol-Traffic Engineering (RSVP-TE) tunnel switching.

Usage Scenario

Bit errors caused by optical fiber aging or optical signal jitter may exist on carrier networks. These bit errors may result in the interruption of services with high quality requirements. If a network uses an RSVP-TE tunnel with traffic engineering (TE) hot standby protection to carry services, you can configure bit-error-triggered RSVP-TE tunnel switching to protect services against bit errors.

Then, if a bit error event occurs, traffic switches between the primary and backup constraint-based routed label switched paths (CR-LSPs) of the RSVP-TE tunnel based on the bit error status of the CR-LSPs.

Pre-configuration Tasks

Before configuring bit-error-triggered RSVP-TE tunnel switching, complete the following tasks:

Configure two unidirectional RSVP-TE tunnels in opposite directions.

Before establishing a unidirectional RSVP-TE tunnel, you must run the label advertise non-null command to enable the egress of the unidirectional tunnel to allocate a non-null label to the penultimate hop. Otherwise, bit-error-triggered RSVP-TE tunnel switching cannot take effect.
Configure a unidirectional hot-standby RSVP-TE tunnel for each unidirectional RSVP-TE tunnel. For configuration details, see Configuring CR-LSP Backup.
Enable Bidirectional Forwarding Detection (BFD) globally on the nodes along the primary and backup CR-LSPs of each unidirectional RSVP-TE tunnel.
Configuring static BFD for CR-LSP or dynamic BFD for CR-LSP.

Procedure

Enable bit error detection on interfaces along the RSVP-TE tunnel.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface view is displayed.
3. Run trap-threshold crc-error packet-error-ratio alarm-threshold coef-value pow-value [ resume-threshold rsm-coef-value rsm-pow-value ] trigger-lsp
  Bit error detection is enabled, and the thresholds for triggering bit error event alarms are set.
  
  To associate bit error event alarms with RSVP-TE tunnel switching, specify trigger-lsp.
  
  The alarm-threshold value equals alarm-coe multiplied by 10^-alarm-pow. If the BER detected by a trunk member interface exceeds the alarm-threshold value, the trunk member interface reports an alarm indicating that a bit error event has occurred.
  
  The resume-threshold value equals resume-coe multiplied by 10^-resume-pow. If the BER detected by a trunk member interface falls below the resume-threshold value, the trunk member interface reports an alarm indicating that the bit error event is over.
  - The resume-threshold value cannot be greater than the alarm-threshold value.
  - If you do not specify the resume-threshold value, the system automatically uses tenth of the alarm-threshold value as the resume-threshold value.
4. Run commit
  The configuration is committed.
Enable bit-error-triggered RSVP-TE tunnel switching.
1. Run system-view
  The system view is displayed.
2. Run interface tunnel interface-number
  The tunnel interface view is displayed.
3. Run mpls te bit-error-detection [ mode { unidirectional | bidirectional } ]
  Bit-error-triggered RSVP-TE tunnel switching is enabled for the current tunnel.
  
  This function supports the following switching modes:
  - unidirectional: In this mode, a bit error event triggers only the current tunnel to perform protection or revertive switching.
  - bidirectional: In this mode, a bit error event triggers both the current tunnel and its reverse tunnel to perform protection or revertive switching.
  In actual situations, RSVP-TE tunnels are usually deployed bidirectionally. The primary CR-LSPs of a pair of RSVP-TE tunnels in opposite directions are on the same path. If an RSVP-TE tunnel performs a primary/backup CR-LSP switchover, its reverse tunnel should also perform a primary/backup CR-LSP switchover to minimize the impact of bit errors on services.
4. Run mpls te reverse-lsp protocol rsvp-te ingress-lsr-id ingress-lsr-id tunnel-id tunnel-id
  The reverse LSP for the current tunnel is specified.
  
  Bit-error-triggered RSVP-TE tunnel switching implements bidirectional switching with the help of reverse LSPs.
5. (Optional) Run mpls te bit-error-detection threshold switch switch-coe switch-pow resume resume-coe resume-pow
  The thresholds for bit-error-triggered protection switching and revertive switching are set.
  
  The switch-coe parameter specifies the protection switching coefficient, and the switch-pow parameter specifies the protection switching power. The formula for calculating the threshold for bit-error-triggered protection switching is as follows:
  
  Protection switching threshold = switch-coe × 10^-switch-pow
  
  Similarly, the resume-coe parameter specifies the revertive switching coefficient, and the resume-pow parameter specifies the revertive switching power. The formula for calculating the threshold for bit-error-triggered revertive switching is similar to the formula for calculating the threshold for bit-error-triggered protection switching.
  
  The revertive switching threshold cannot be greater than the protection switching threshold.
6. Run commit
  The configuration is committed.