Configuring ECN

CloudEngine 12800 and 12800E V200R019C10 Configuration Guide - QoS

This document describes the configurations of QoS functions, including MQC, priority mapping, traffic policing, traffic shaping, interface-based rate limiting, congestion avoidance, congestion management, packet filtering, redirection, traffic statistics, and ACL-based simplified traffic policy.

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Configuring ECN

Context

Combination of WRED and Explicit Congestion Notification (ECN) enables a terminal device to detect congestion and notify the source of congestion. After receiving the notification, the source reduces the rate of sending packets to prevent congestion from aggravating.

To limit the rate of packets sent by the upstream device to prevent congestion aggravation, configure ECN.

Global ECN cannot be enabled in a VS except Admin-VS in port mode, whereas global ECN enabled in Admin-VS takes effect in a VS in port mode. Global ECN can be enabled in a VS in port group mode and takes effect only in this VS.
For the CE12800E equipped with ED-E, EG-E, and EGA-E series cards, after ECN is enabled for a queue, if congestion occurs, the device does not randomly discard packets. Instead, the device randomly marks packets based on the WRED drop profile. When the queue length reaches the upper threshold in the WRED drop profile, the device starts to discard new packets entering the queue. In this case, ECN cannot reset the CE field.
For switches excluding the CE12800E equipped with ED-E, EG-E, and EGA-E series cards, after ECN is enabled for a queue, if congestion occurs, the device does not randomly discard packets. Instead, the device randomly marks packets based on the ECN profile.

Procedure

Configure ECN on the CE12800.
1. Run system-view
  The system view is displayed.
2. Run qos ecn
  Global ECN is enabled.
3. Run drop-profile drop-profile-name
  A WRED drop profile is created and the drop profile view is displayed.
  
  By default, the WRED drop profile default exists. The WRED drop profile default can be modified but cannot be deleted.
4. Run ecn { buffer-size low-limit low-buffer-size high-limit high-buffer-size | buffer-size cell low-limit low-buffer-cell-size high-limit high-buffer-cell-size | low-limit low-limit-percentage high-limit high-limit-percentage } discard-percentage discard-percentage-value
  ECN parameters including the absolute values of upper and lower drop thresholds, upper and lower drop thresholds in percentage, and maximum drop probability are configured.
  
  By default, the absolute values of upper and lower drop thresholds, upper and lower drop thresholds in percentage, and maximum drop probability are not set.
5. Run quit
  Exit from the WRED drop profile view.
6. Run interface interface-type interface-number
  The interface view is displayed.
7. Run qos queue queue-index ecn drop-profile-name
  ECN is enabled for a specified queue.
8. Run commit
  The configuration is committed.
Configure ECN on the CE12800E.
1. Run system-view
  The system view is displayed.
2. Run drop-profile drop-profile-name
  A WRED drop profile is created and the drop profile view is displayed.
  
  By default, the WRED drop profile default exists. The WRED drop profile default can be modified but cannot be deleted.
3. (Optional) Run ecn weight weight-value
  The ECN weight is configured.
  
  By default, the ECN weight is 4.
  
  Only the CE12800E equipped with FD-X series cards supports this command.
4. (For the CE12800E equipped with ED-E, EG-E, and EGA-E series cards) Run color { green | red | yellow } { buffer-size low-limit low-buffer-size high-limit high-buffer-size | low-limit low-limit-percentage high-limit high-limit-percentage } discard-percentage discard-percentage
  WRED parameters are set.
  
  By default, the upper drop threshold, lower drop threshold, and maximum drop probability of a WRED drop profile are all 100, and absolute values of upper and lower drop thresholds are not configured.
5. (For the CE12800E equipped with FD-X series cards) Run ecn { buffer-size low-limit low-buffer-size high-limit high-buffer-size | buffer-size cell low-limit low-buffer-cell-size high-limit high-buffer-cell-size | low-limit low-limit-percentage high-limit high-limit-percentage } discard-percentage discard-percentage-value
  WRED parameters are set.
  
  By default, the upper and lower drop thresholds in percentage, absolute values of upper and lower drop thresholds, and maximum drop probability are not set.
6. Run quit
  Exit from the WRED drop profile view.
7. Run interface interface-type interface-number
  The interface view is displayed.
8. Run qos wred drop-profile-name
  The WRED drop profile is applied to an interface.
9. Run qos queue queue-index ecn
  ECN is enabled for a specified queue.
10. Run commit
  The configuration is committed.

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Updated: 2021-04-01

Document ID: EDOC1100138142

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This document describes the configurations of QoS functions, including MQC, priority mapping, traffic policing, traffic shaping, interface-based rate limiting, congestion avoidance, congestion management, packet filtering, redirection, traffic statistics, and ACL-based simplified traffic policy.

Context

Procedure

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