(Optional) Configuring Switching Between I-PMSI and S-PMSI Tunnels

Procedure

1. Run system-view

   The system view is displayed.

2. Run ip vpn-instance vpn-instance-name

   The VPN instance view is displayed.

3. Run ipv6-family

   The VPN instance IPv6 address family view is displayed.

4. Run multicast ipv6 routing-enable

   Multicast routing is enabled in the VPN instance IPv6 address family view.

5. Run mvpn

   The VPN instance IPv6 address family MVPN view is displayed.

6. Run ipmsi-to-spmsi switch immediately

   Immediate switching from an I-PMSI tunnel to an S-PMSI tunnel is configured.

   After immediate switching from an I-PMSI tunnel to an S-PMSI tunnel is configured, upon the generation of an (S, G) entry with an MTI as the outbound interface on the sender PE, an S-PMSI tunnel is created and traffic is immediately switched from an I-PMSI tunnel to the S-PMSI tunnel.

   Compared with the original implementation, immediate switching from an I-PMSI tunnel to an S-PMSI tunnel allows traffic corresponding to an (S, G) entry to be switched to an S-PMSI tunnel earlier, thereby reducing multicast traffic loss.

   

   After this command is run, the switching threshold configured in the MVPN S-PMSI view does not take effect.

7. Run spmsi-tunnel

   The MVPN S-PMSI view is displayed.

8. Run group group-address group-mask-length [ source source-address source-mask-length ] [ threshold threshold-value ] { mldp | rsvp-te p2mp-template p2mp-te-template-name } [ limit number ]

   The address pool range and criteria for switching between I-PMSI and S-PMSI tunnels are configured.

9. (Optional) Run switch-delay switch-delay

   A delay for switching traffic from the I-PMSI tunnel to an S-PMSI tunnel is configured for the VPN instance.

   The device starts a switchover delay timer when using the I-PMSI tunnel to transmit multicast traffic. The device keeps monitoring the multicast traffic forwarding rate before the switchover delay timer expires. If the forwarding rate is consistently higher than the specified switchover threshold throughout the timer lifecycle, the device switches multicast traffic from the I-PMSI tunnel to an S-PMSI tunnel. If the forwarding rate is consistently lower than the specified switchover threshold throughout the timer lifecycle, the device still uses the I-PMSI tunnel to transmit multicast traffic.

10. (Optional) Run holddown-time interval

    A delay for switching traffic from an S-PMSI tunnel back to the I-PMSI tunnel is configured.

    In some cases, the multicast traffic forwarding rate may fluctuate around the specified switchover threshold. To prevent multicast data traffic from being frequently switched between S-PMSI and I-PMSI tunnels, the device starts the switchback delay timer when the forwarding rate falls below the specified threshold rather than performing an immediate switchback. The device keeps monitoring the forwarding rate before the switchback delay timer expires. If the rate remains consistently lower than the threshold throughout the timer period, the device switches multicast traffic back to the I-PMSI tunnel. Otherwise, the device still uses the S-PMSI tunnel to forward multicast traffic.

11. (Optional) Run tunnel-detect-delay tunnel-detect-delay

    A delay for checking tunnel status when the bearer tunnel of VPN instance multicast data changes is configured. The tunnel-detect-delay command needs to be run only on the receiver PE, not on the sender PE.

    In RSVP-TE P2MP tunnel dual-root 1+1 protection scenarios, multicast data may be switched from the primary I-PMSI tunnel to the backup I-PMSI tunnel if the S-PMSI tunnel is not ready during data switching. To solve this problem, start a tunnel status check delay timer on leaf PEs:

    • Before the timer expires, leaf PEs delete tunnel protection groups to skip the status check of the primary I-PMSI or S-PMSI tunnel.
    • After the timer expires, leaf PEs start to check the primary I-PMSI or S-PMSI tunnel status again.

12. Run commit

    The configuration is committed.