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CoS Three-Level Hierarchical Scheduling on MPLS Pseudowire Subscriber Interfaces

In three-level hierarchical scheduling, the CoS scheduler nodes at level 1, level 2, and level 3 form a scheduling hierarchy. You can configure many different three-level scheduling hierarchies, depending on the location of the interface set and the use of underlying interfaces. In all variations, the physical interface on which the logical tunnel resides is a level 1 CoS scheduler node and the queues reside at level 4. Three-level scheduling hierarchies can have up to eight class of service queues. Table 1summarizes the most common three-level hierarchical scheduling configurations and shows the interface hierarchy and CoS scheduler nodes.

Table 1: Three-Level Hierarchical Scheduling–Interface Hierarchy Versus CoS Scheduling Node Levels

Level 1

Level 2

Level 3

Level 4

Physical interface

Pseudowire interface set

Pseudowire service logical interfaces

One or more queues

Physical interface

Pseudowire transport logical interface

Pseudowire interface set

One or more queues

Physical interface

Pseudowire transport logical interface

Pseudowire service logical interfaces

One or more queues

Three-Level Scheduling Hierarchy: Pseudowire Logical Interfaces over a Transport Logical Interface

Figure 1 shows an MPLS pseudowire three-level scheduling hierarchy that includes two pseudowire service logical interfaces over a pseudowire transport logical interface. This variation uses the following scheduler nodes:

  • Level 4—Forwarding class-based queues

  • Level 3—Pseudowire service logical interfaces (ps0.1 and ps0.2) for subscriber sessions

  • Level 2—Pseudowire transport logical interface (ps0.0)

  • Level 1—Common/shared physical interface of the logical tunnel anchor point

You apply the traffic-control profiles at the pseudowire transport logical interfaces (level 2) and the pseudowire service logical interfaces (level 3).

Figure 1: Three-Level Scheduling Hierarchy Case 1: Pseudowire Service Logical Interfaces over a Transport Logical InterfaceThree-Level Scheduling Hierarchy Case 1: Pseudowire Service Logical Interfaces over a Transport Logical Interface

Three-Level Scheduling Hierarchy : Pseudowire Service Logical Interfaces over a Pseudowire Service Interface Set

Figure 2 shows another variation of MPLS pseudowire three-level hierarchical scheduling that includes two pseudowire service logical interfaces over a pseudowire service interface set. This variation uses the following CoS scheduler nodes:

  • Level 4—Forwarding class-based queues

  • Level 3—Pseudowire service logical interfaces (ps0.1 and ps0.2)

  • Level 2—Pseudowire service interface set

  • Level 1—Common/shared physical interface of the logical tunnel anchor point

You apply the traffic-control profile at the pseudowire service interfaces (level 3) and at the interface set (level 2). This variation is most useful for subscriber edge deployments.

Figure 2: Three-Level Scheduling Hierarchy Case 2: Pseudowire Service Logical Interfaces over a Pseudowire Service Interface SetThree-Level Scheduling Hierarchy Case 2: Pseudowire Service Logical Interfaces over a Pseudowire Service Interface Set

Three-Level Scheduling Hierarchy Combined Deployment Scenario

Figure 3 shows a deployment scenario that combines the three-level hierarchical scheduling scenarios in Figure 1 and Figure 2.

Figure 3: Three-Level Hierarchical Scheduling for MPLS Pseudowire Subscriber Interfaces—Deployment ScenarioThree-Level Hierarchical Scheduling for MPLS Pseudowire Subscriber Interfaces—Deployment Scenario

This variation uses the following CoS scheduler nodes:

  • Level 4—Forwarding class-based queues

  • Level 3—Pseudowire service logical interfaces (ps0.1, ps0.2, ps1.1, and ps1.2)

  • Level 2—Service interface set for pseudowire service interfaces (ps0.1 and ps0.2) and transport logical interface (ps1.0) for the pseudowire service logical interfaces (ps1.1 and ps1.2)

  • Level 1—Common/shared physical interface of the logical tunnel anchor point

You apply the traffic-control profiles to the interfaces at both level 2 and level 3, as well as the interface set at level 2.

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