Users Guide

Command Modes CONFIGURATION (conf-qos-policy-out)
Command History
This guide is platform-specific. For command information about other platforms, see the relevant Dell Networking
OS Command Line Reference Guide.
Version Description
9.8(1.0) Introduced on the Z9100-ON.
9.8(0.0P5) Introduced on the S4048-ON.
9.8(0.0P2) Introduced on the S3048-ON.
9.7(0.0) Introduced on the S6000-ON.
9.2(1.0) Introduced on the Z9500.
9.0.2.0 Introduced on the S6000.
8.3.19.0 Introduced on the S4820t.
8.3.11.1 Introduced on the Z9000.
8.3.7.0 Introduced on the S4810.
Usage Information
When you enable wred ecn, and the number of packets in the queue is below the minimum threshold, packets
are transmitted per the usual WRED treatment.
When you enable wred ecn, and the number of packets in the queue is between the minimum threshold and the
maximum threshold, one of the following two scenarios can occur:
• If the transmission endpoints are ECN-capable and traffic is congested, and the WRED algorithm determines
that the packet should have been dropped based on the drop probability, the packet is transmitted and marked
so the routers know the system is congested and can slow transmission rates.
• If neither endpoint is ECN-capable, the packet may be dropped based on the WRED drop probability. This
behavior is the identical treatment that a packet receives when WRED is enabled without ECN configured on
the router.
When you enable wred ecn, and the number of packets in the queue is above the maximum threshold, packets
are dropped based on the drop probability. This behavior is the identical treatment a packet receives when WRED
is enabled without ECN configured on the router.
Related Commands
• wred-profile — creates a WRED profile and name that profile.
wred weight
Configure the weight factor for computation of average-queue size. This weight value applies to front-end ports. This mechanism to
configure a weight for WRED and ECN functionality for front-end ports is supported on the S6000 and Z9000 platforms.
S6000–ON
Syntax
[no] wred weight number
Quality of Service (QoS) 1261