Configuring Bit-Error-Triggered PW Switching

Usage Scenario

In a scenario in which a Resource Reservation Protocol-Traffic Engineering (RSVP-TE) tunnel with traffic engineering (TE) hot standby protection carries Layer 2 virtual private network (L2VPN) services and PW redundancy is configured, you can configure bit-error-triggered PW switching in addition to bit-error-triggered RSVP-TE tunnel switching. If the primary and backup constraint-based routed label switched paths (CR-LSPs) of the RSVP-TE tunnel are both in the excessive bit error rate (BER) state or the TE hot standby tunnel fails and bit-error-triggered RSVP-TE tunnel switching cannot protect services against bit errors, bit-error-triggered PW switching can do so.

The principles for bit-error-triggered PW switching are as follows:

• If the RSVP-TE tunnel carrying the primary PW enters the excessive BER state but the RSVP-TE tunnel carrying the secondary PW is in the normalized BER state, traffic switches to the secondary PW.

• If the RSVP-TE tunnel carrying the primary PW enters the normalized BER state, traffic switches back to the primary PW.

• If the RSVP-TE tunnels carrying the primary and secondary PWs are both in the excessive BER state, traffic travels along the primary PW.

The bit error status of the RSVP-TE tunnel carrying the PW refers to the bit error status of the CR-LSP that transmits traffic in the tunnel.

A PW can be either a single-segment PW (SS-PW) or a multi-segment PW (MS-PW):

• For an SS-PW, bit-error-triggered protection switching is enabled on endpoint provider edges (PEs).

• For an MS-PW, bit-error-triggered protection switching is enabled on both endpoint PEs and intermediate superstratum provider edges (SPEs).

Pre-configuration Tasks

Before configuring bit-error-triggered PW switching, complete the following tasks:

• Configure PW redundancy.

• Configure bit-error-triggered RSVP-TE tunnel switching.