
Queue Group Commands
Page 378
7950 XRS Quality of Service Guide
high-prio-only
Syntax
high-prio-only
percent
no high-prio-only
Context
config>qos>qgrps>egr>qgrp>queue
config>qos>qgrpid>ing>qgrp>queue
config>qos>qgrpid>ing>qgrp>policer
Description
The
high-prio-only
command configures the percentage of buffer space for the queue, used exclusively by
high priority packets. The specified value overrides the default value for the context.
The priority of a packet can only be set in the SAP ingress QoS policy and is only applicable on the ingress
queues for a SAP. The
high-prio-only
parameter is used to override the default value derived from the
net-
work-queue
command.
The
no
form of this command restores the default high priority reserved size.
Parameters
percent —
The percentage reserved for high priority traffic on the queue. If a value of 10KBytes is desired,
enter the value 10.
Values
0 — 100, default
mbs
Syntax
mbs
size
[
bytes
|
kilobytes
]
no mbs
Context
config>qos>qgrps>egr>qgrp>queue
config>qos>qgrpid>ing>qgrp>queue
config>qos>qgrpid>egr>qgrp>policer
config>qos>qgrpid>ing>qgrp>policer
Description
For queues, the Maximum Burst Size (MBS) command the default maximum buffer size for the template
queue. The value is given in kilobytes.
The MBS value is used by a queue to determine whether it has exhausted all of its buffers while enqueuing
packets. Once the queue has exceeded the amount of buffers allowed by MBS, all packets are discarded until
packets have been drained from the queue.
The port Ethernet access ingress and egress queue group context for mbs provides a mechanism for overrid-
ing the default maximum size for the queue.
The sum of the MBS for all queues on an ingress access port can oversubscribe the total amount of buffering
available. When congestion occurs and buffers become scarce, access to buffers is controlled by the RED
slope a packet is associated with. A queue that has not exceeded its MBS size is not guaranteed that a buffer
will be available when needed or that the packets RED slope will not force the discard of the packet. Setting
proper CBS parameters and controlling CBS over-subscription is one major safeguard to queue starvation
(when a queue does not receive its fair share of buffers). Another is properly setting the RED slope parame-
ters for the needs of services on this port.
If the CBS value is larger than the MBS value, an error will occur, preventing the MBS change.
Summary of Contents for 7950
Page 12: ...Page 12 7950 XRS Quality of Service Guide List of Figures ...
Page 16: ...Preface Page 16 7950 XRS Quality of Service Guide ...
Page 82: ...Editing QoS Policies Page 82 7950 XRS Quality of Service Guide ...
Page 90: ...Applying Network Queue Policies Page 90 7950 XRS Quality of Service Guide ...
Page 96: ...Editing QoS Policies Page 96 7950 XRS Quality of Service Guide ...
Page 98: ...Command Hierarchies Page 98 7950 XRS Quality of Service Guide ...
Page 108: ...Command Hierarchies Page 108 7950 XRS Quality of Service Guide ...
Page 156: ...Basic Configurations Page 156 7950 XRS Quality of Service Guide exit exit ...
Page 164: ...Queue Depth Monitoring Page 164 7950 XRS Quality of Service Guide ...
Page 304: ...Service Queue QoS Policy Commands Page 304 7950 XRS Quality of Service Guide ...
Page 368: ...Command Hierarchies Page 368 7950 XRS Quality of Service Guide ...
Page 430: ...Configuration Commands Page 430 7950 XRS Quality of Service Guide ...
Page 532: ...Editing QoS Policies Page 532 7950 XRS Quality of Service Guide ...
Page 552: ...Editing Advanced Policies Page 552 7950 XRS Quality of Service Guide ...
Page 600: ...Command Hierarchies Page 600 7950 XRS Quality of Service Guide ...
Page 602: ...QoS Commands Page 602 7950 XRS Quality of Service Guide ...
Page 610: ...Standards and Protocols Page 610 7950 XRS Quality of Service Guide ...
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