Dell Command Line Reference Guide for the S4048–ON System 9.14.2.8

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qos-policy-buffer

Create a QoS policy buffer and enter the configuration mode to configure the no-drop queues, ingress buffer size, buffer limit for pausing, and buffer offset limit for resuming.

Syntax
qos-policy-buffer queue queue-num pause no-drop queue buffer-size size pause-threshold threshold-value resume-offset threshold-value shared-threshold-weight size
Parameters
policy-name
Name of the QoS policy buffer that is applied to an interface for this setting to be effective in conjunction with the DCB input policy. You can specify the shared buffer threshold limit, the ingress buffer size, buffer limit for pausing the acceptance of packets, and the buffer offset limit for resuming the acceptance of received packets. This method of configuration enables different peer-provided and administrative priorities to be set up because the intended queue is directly configured instead of determining the priority to queue mapping for local and remote parameters.
queue 0 to queue 7
Specify the queue number to which the QoS policy buffer parameters apply
pause
Pause frames to be sent at the specified buffer limit levels and pause packet settings
no-drop
The packets for this queue must not be dropped
value
Enter a number in the range of 0 to 7 to denote the priority to be allocated to the dynamic buffer control mechanism
buffer-size
Ingress buffer size
size
Size of the ingress buffer in KB. Enter a number in the range of 0 to 7787. The default is 45 KB.
pause-threshold
Buffer limit for pause frames to be sent
threshold-value
Buffer limit at which the port sends the pause to peer in KB. Enter a number in the range of 0 to 7787. The default is 10 KB.
resume-offset
Buffer offset limit for resuming in KB
threshold-value
Buffer offset limit at which the port resumes the peer in KB. Enter a number in the range of 1 to 7787. The default is 10 KB.
shared-threshold-weight
Buffer shared threshold weight
size
Weightage of the priorities on the shared buffer size in the system. Enter a number in the range of 0 to 9. The default shared threshold weight is 10.
Default
The default size of the ingress buffer is 45 KB. The default buffer limit at which the port sends the pause to peer and recommences the sending of packets to the peer is 10 KB. The default threshold weight of the shared buffer space is 10.
Command Modes
DCB-BUFFER-THRESHOLD mode
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(0.0)
Introduced on the S3048-ON and S4048-ON.
9.7(0.0)
Introduced on the S6000-ON and Z9500.
9.3(0.0)
Introduced on the S4810, S4820T, S6000, and MXL platforms.
Usage Information

You must apply this buffer policy at the interface level for the attributes to be applicable in conjunction with the DCB input policy.

For each QoS policy buffer, you can specify the shared buffer threshold limit, the ingress buffer size, buffer limit for pausing the acceptance of packets, and the buffer offset limit for resuming the acceptance of received packets. When PFC detects congestion on a queue for a specified priority, it sends a pause frame for the 802.1p priority traffic to the transmitting device.

You can use set up both the administrative and peer-related PFC priorities. For example, you can configure the intended buffer configuration for all 8 priorities. If you configure the number of lossless queues as 4 and if the administrator-configured priorities configured within the DCB input policy is applied, then the configuration for those priorities are pre-designed. However, if the peer-provided priorities are applied, although a DCB input policy is present, the peer-provided priorities become effective for buffer configuration. This method of configuration provides an easy and flexible technique to accommodate both administratively-configured and peer-configured priorities.

Example
Dell(conf)# qos-policy-buffer test

Dell(conf-qos-policy-buffer)#queue 0 pause no-drop buffer-size 128000 pause-threshold 103360 resume-threshold 83520

Dell(conf-qos-policy-buffer)# queue 4 pause no-drop buffer-size 128000 pause-threshold 103360 resume-threshold 83520


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