Configuring Congestion Management on a Stack Interface (Schedule Template Mode)

Pre-configuration Tasks

Configure congestion management on a stack interface when the network intermittently becomes congested. Once congestion management is configured, the sequence at which packets are forwarded is determined according to the defined scheduling policy. High-priority services are scheduled preferentially.

Before configuring congestion management on a stack interface, complete the following tasks:

Perform the stack configuration.
Configure priority mapping on inbound interface of packets.

Context

After the stack is configured, stack protocol packets and packets between chassis are exchanged on the stack interface. If a large number of packets are exchanged, congestion may occur on the stack interface. As a result, core services such as video services and voice services cannot be processed in a timely manner. You can set the scheduling mode on the stack interface so that services with the same priority are processed in the same manner and services with different priorities are processed based on weights.

Only the following switches support congestion management on a stack interface using a schedule template:

S2720-EI
S5720I-SI (excluding the S5720I-10X-PWH-SI-AC and S5720I-6X-PWH-SI-AC), S5720-LI, S5720S-LI, S5720-SI, and S5720S-SI
S5730-SI and S5730S-EI
S6720-LI, S6720S-LI, S6720-SI, and S6720S-SI

Procedure

Run system-view
The system view is displayed.
Run qos schedule-profile profile-name
A global schedule template is created and the schedule template view is displayed.
Run qos { pq | wrr | drr }
The scheduling mode of a port queue is set to PQ, WRR, or WDRR.

By default, WRR scheduling is used.
Configure WRR or WDRR weights for port queues.
- If the scheduling mode is WRR, run the qos queue queue-index wrr weight weight command to set the WRR weight for a port queue.
  
  By default, the weight in WRR mode is 1.
  
  Perform this step only when the scheduling mode of a port queue is set to PQ+WRR or WRR.
  
  When WRR scheduling is applied and the weight of a queue is set to 0, the queue applies PQ scheduling and other queues apply WRR scheduling. When configuring the PQ+WRR scheduling mode, ensure that the queues with weight 0 (queue using PQ scheduling) are consecutively configured, without being interrupted by the configuration of the queues using WRR scheduling.
- If the scheduling mode is WDRR, run the qos queue queue-index drr weight weight command to set the WDRR weight for a port queue.
  
  By default, the weight in WDRR mode is 1.
  
  Perform this step only when the scheduling mode of a port queue is set to WDRR or PQ+WDRR.
  
  When WDRR scheduling is applied and the weight of a queue is set to 0, the queue applies PQ scheduling and other queues apply WDRR scheduling. When configuring the PQ+WDRR scheduling mode, ensure that the queues with weight 0 (queue using PQ scheduling) are consecutively configured, without being interrupted by the configuration of the queues using WDRR scheduling.
Run quit
Return to the system view.
Run stack-port qos schedule-profile profile-name
The scheduling profile is applied.

Verifying the Configuration

Run the display qos configuration interface [ interface-type interface-number ] command to check all the QoS configurations on a specified interface.
Run the display qos queue statistics interface interface-type interface-number [ queue queue-index ] command to check the queue-based traffic statistics on the interface.