Example: Compound Shared Shaping for ATM VPs

Figure 28 shows a compound shared shaper for a VP interface. VP shared shaping enables a shared shaper to apply to all the aggregate rates of all VCs within the VP.

In this example, the VP is shaped to a compound shared rate of 5 Mbps. The voice traffic gets strict priority scheduling for up to 400 Kbps of the shared rate on the VP. The video traffic gets up to 2 Mbps of the remaining 4.6–5 Mbps on the VP. Finally, the data traffic has the last claim to the remaining 2.6–3 Mbps of shared VP bandwidth.

This configuration enables data traffic to flow at 2.6 Mbps when voice and video are both using their limit. When both voice and video are quiescent, data can flow at the full 5 Mbps shared rate.

The QoS profile used in this example is appropriate for low-CDV mode. If the provider configures a shapeless VP tunnel in the SAR, QoS sets the SAR shaper for the VP to match the 5 Mbps shared-shaping rate, and the CDV is bounded for the VP tunnel. VP-level queuing does not guarantee fairness to the voice and video for each VC.

Figure 28: VP Compound Shared Shaping Example

To configure VP compound shared shaping:

1. Configure the traffic classes, traffic-class groups, and additional scheduler profiles.
2. Configure the scheduler profile that defines the shared shaper and the profiles that apply the legacy shaper.

   host1(config)#scheduler-profile shared-5Mbps

   host1(config-scheduler-profile)#shared-shaping-rate 5000000 burst 32768 auto

   host1(config-scheduler-profile)#exit

3. Configure the scheduler profile for AF (video) traffic.

   host1(config)#scheduler-profile 2Mbps

   host1(config-scheduler-profile)#shaping-rate 2000000

4. Configure the scheduler profile for EF (voice) traffic.

   host1(config)#scheduler-profile 400Kbps

   host1(config-scheduler-profile)#shaping-rate 400000

   host1(config-scheduler-profile)#exit

5. Configure the QoS profile.

   host1(config)#qos-profile vpSharedShaping

6. Create group nodes.

   host1(config-qos-profile)#atm group AF scheduler-profile default

   host1(config-qos-profile)#atm group EF scheduler-profile default

7. Create VP nodes for each group and for traffic in the default group. The scheduler profile containing the shared-shaping rate is applied to the VP node that is in the default group and contains the best-effort queue.

   host1(config-qos-profile)#atm-vp node scheduler-profile shared-5Mbps

   host1(config-qos-profile)#atm-vp node group AF scheduler-profile 2Mbps

   host1(config-qos-profile)#atm-vp node group EF scheduler-profile 400Kbps

8. Create a VC node for the default group.

   host1(config-qos-profile)#atm-vc node

9. Create queues for the best-effort, video, and voice traffic.

   host1(config-qos-profile)#atm-vc queue traffic-class best-effort

   host1(config-qos-profile)#atm-vc queue traffic-class AF

   host1(config-qos-profile)#atm-vc queue traffic-class EF

   host1(config-qos-profile)#exit

10. Attach the QoS profile to an ATM subinterface.

    host1(config)#interface atm 11/0.1

    host1(config-interface)#qos-profile vpSharedShaping

In this example, the constituents of the VP shared shaper are the VP 1 default group node, the VP 1 Group EF node, and the VP 1 Group AF node. The available bandwidth is strictly allocated in the following order:

1. VP1 EF group node
2. VP1 AF group node
3. VP1 default group node

Related Topics

• Configuring Compound Shared Shaping
• Compound Shared Shaping Overview

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