Service Interruption After Enabling the Shaping Function of the N1EMS4 Board

After the shaping function of the N1EMS4 board is enabled for egress port queues, the services are interrupted.

Product

• OptiX OSN 3500
• OptiX OSN 7500
• OSN2500

Fault Type

• RPR
• Ethernet fault

Configuration problem

Symptom

Figure 1 shows the VCTRUNK-shared EVPL service between NE2 and NE3.

Figure 1 Configuration of the VCTRUNK-shared EVPL service

Two pairs of users (D and D', and E and E') share the 300 Mbit/s bandwidth of VCTRUNK1.

1. Create a flow of the Port type for PORT1 and PORT2 separately.
2. Create a CoS of the simpletype. Groom the port flow of PORT1 to queue 1 of VCTRUNK1, and groom the port flow of PORT2 to queue 3 of VCTRUNK1.
3. Enable the traffic shaping function for queue 3 of VCTRUNK1. Set the CIR to 300 Mbit/s.
4. Enable the traffic shaping function for queue 1 of VCTRUNK1. Use the default shaping parameter values.

Now if the traffic that enters PORT2 reaches a rate of 300 Mbit/s, the service of PORT1 is interrupted. Hence, although certain remaining bandwidth is available, it cannot allocated to queue 1.

Cause Analysis

This problem has the following possible causes.

1. In this fault case, the priority of queue 3 is higher than the priority of queue 1. As a result, the packets of the higher priority queue 3 occupy the entire 300 Mbit/s bandwidth, and there is no remaining bandwidth for the lower priority queue 1. Consequently, the service between D and D' is interrupted.
2. The shaping function is enabled for queue 1, but the shaping bandwidth is not set. As the default shaping bandwidth is 0, the service is interrupted.

Procedure

1. Cause 1: The packets in queue 3 of higher priority occupy all the available bandwidth.
   1. Decrease the bandwidth of the higher priority queue 3.
      1. On the Main Topology, right-click the NE icon and choose NE Explorer from the shortcut menu.
      2. Select the relevant Ethernet board in the Object Tree. Choose Configuration > QoS Management > Port Shaping Management from the Function Tree.
      3. Set the committed information rate (CIR) and burst size (less than 300 Mbit/s).
2. Cause 2: The shaping function is enabled for queue 1, but the committed bandwidth (CIR) of the shaping function is not set.
   1. Set the shaping bandwidth for queue 1.
      1. On the Main Topology, right-click the NE icon and choose NE Explorer from the shortcut menu.
      2. Select the relevant Ethernet board in the Object Tree. Choose Configuration > QoS Management > Port Shaping Management from the Function Tree.
      3. Select queue 1, and then set the relevant parameters for the queue.

Similar Problems

After a flow is bound with a CAR, the service is interrupted. The possible cause is that, although the CAR is enabled, the CIR and PIR (which are both 0 by default) are not set for the CAR.

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