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Configuring Four-Level Hierarchical Scheduling on vMX

Starting with Junos OS Release 17.3R1, four-level hierarchical scheduling for up to 16 level 2 CoS scheduler nodes is supported on vMX routers. The level 2 node maps to the interface set or VLAN (logical interface). Two of the level 2 nodes are used for control traffic. If you configure less than four nodes, no commit errors are displayed but there are not enough nodes for other applications to use. Different interfaces can have a different number of level 2 nodes. The interface can be an inline service interface.

To configure four-level hierarchical scheduling:

  1. Hierarchical CoS is disabled by default. Configure flexible queuing to enable CoS.

    The FPC reboots if you enable flexible queuing.

  2. Enable hierarchical scheduling.
  3. Set the maximum number of hierarchical scheduling levels for node scaling to 3. If the maximum-hierarchy-levels option is not configured, it is automatically set to 2.
  4. Specify the maximum number of level 2 scheduler nodes; only 1, 2, 4, 8, and 16 are valid values. The default value is 4. We recommend that you do not configure less than four nodes because two of the nodes are used for control traffic.

    For example:


    This configuration must be present before you reboot the FPC.