how to configure the Switch-MDT of Multicast VPN

Created: Jul 31, 2018 10:49:28Latest reply: Aug 1, 2018 12:15:01 326 1 0 0

When public network data packets are forwarded along a Share-MDT, all PE devices bound to the VPN instance receive multicast data packets, regardless of whether the VPN sites connected to them have receivers. This wastes bandwidth and increases resource usage on PE devices. The Switch-MDT mechanism conserves bandwidth and reduces loads on PE devices. When multicast data packets are forwarded along a Switch-MDT, PE devices with no receivers attached will not receive these packets. You can define the condition for a switchover from the Share-MDT to the Switch-MDT.

Perform the following steps on the PE connected to a multicast source.

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    ip vpn-instance vpn-instance-name

    The VPN instance view is displayed.

  3. (Optional) Run:

    ipv4-family

    The IPv4 address family is enabled for the VPN instance, and the VPN instance IPv4 address family view is displayed.

    By default, the VPN instance IPv4 address family is enabled after a router distinguisher (RD) and a VPN target are configured for a VPN instance.

  4. Run:

    multicast-domain switch-group-pool switch-group-pool { network-mask | network-mask-length } [ threshold threshold-value | acl advanced-acl-number ] *

    A Switch-Group-Pool and the switchover condition are configured.

    • On a PE, the Switch-Group-Pool ranges configured for different VPN instances cannot overlap.

    • By default, the switchover threshold is 0 kbit/s and no switchover condition is specified. That is, all public network data packets are transmitted along the Share-MDT and will not switch to the Switch-MDT.

  5. (Optional) Run:

    multicast-domain switch-delay switch-delay

    The delay for a switchover to the Switch-MDT is set.

    By default, the delay for a switchover to the Switch-MDT is 5 seconds. When the forwarding rate exceeds the switchover threshold, the system does not immediately perform a switchover. Instead, the system starts the Switch-Delay timer and continues detecting the data forwarding rate. If the rate remains higher than the switchover threshold when the Switch-Delay timer expires, the transmission path of data packets is switched to the Switch-MDT. If the rate falls below the switchover threshold, data packets are still forwarded along the Share-MDT.

  6. (Optional) Run:

    multicast-domain holddown-time interval

    The delay of a switchback from the Switch-MDT to the Share-MDT is set.

    • By default, the delay of a switchback to the Share-MDT is 60 seconds. When the forwarding rate falls below the switchover threshold, the system does not immediately perform a switchback. Instead, the system starts the Switch-Holddown timer. If the rate remains lower than the switchover threshold after the Switch-Holddown timer expires, the transmission path of data packets is switched back to the Share-MDT. If the rate becomes higher than the switchover threshold, packets are still forwarded along the Switch-MDT.

    • The rate of VPN multicast data packets may fluctuate above and below the switchover threshold when the network is unstable. Enabling the Switch-Delay and Switch-Holddown timers simultaneously prevents frequent switchovers between the Share-MDT and Switch-MDT in this case.

    • If a VPN instance has many multicast forwarding entries, the time taken to collect multicast traffic statistics will exceed the default Switch-Holddown timer value. In this case, increase the Switch-Holddown timer value to prevent frequent switchovers between the Switch-MDT and Share-MDT. Table 1 lists the recommended Switch-Holddown timer values in various conditions.

      Table 1 Recommended Switch-Holddown timer values
      Number of Multicast Forwarding Entries in a VPN Instance Recommended Switch-Holddown Timer Value
      1024 60s
      2048 128s
      4094 256s

  7. (Optional) Run:

    multicast-domain switch-without-register

    The source PE is disabled from sending registration packets to the RP and establishing the public network SPT before the Switch-Group address is used to encapsulate VPN data packets.

    By default, the source PE sends registration packets to the RP and establishes the public network SPT before the Switch-Group address is used to encapsulate VPN data packets.

  8. (Optional) Run:

    multicast-domain log switch-group-reuse

    The system is configured to log the reuse of the Switch-Group address.

    By default, the system does not log the reuse of Switch-Group addresses. In the VPN instance that the source PE is bound to, multicast group addresses can be reused when the Switch-Group-Pool cannot provide enough addresses for Switch-MDT switchovers.

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faysalji  Visitor   Created Aug 1, 2018 12:15:01 Helpful(0) Helpful(0)

Thanks
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