Service Egress and Ingress QoS Policies
320
Quality of Service Guide
3HE 11014 AAAC TQZZA Edition: 01
The priority of a packet can only be set in the service ingress policy and is only applicable on
the ingress queues for a SAP. The profile state is used for enqueuing priority at sap-egress.
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
Values 0 to 100 | default1
Default 10
mbs
Syntax mbs size [bytes | kilobytes]
no mbs
Context config>qos>sap-ingress>queue
config>qos>sap-egress>queue
Description This command sets the Maximum Burst Size (MBS) value for the buffers of the specified
queue. The value is configured in bytes or kilobytes, and overrides the default MBS value.
The default configuration is in kilobytes.
The config>qos>sap-ingress>info detail and sap-egress>info detail screens show the
MBS in terms of bytes, unless it is a multiple of 1000. In that case, the display shows the MBS
in kilobytes. For example, entering mbs 200 or mbs 200 kilobytes configures and displays
“200 kilobytes”, entering mbs 200000 bytes also configures and displays “200 kilobytes”, and
entering mbs 200100 bytes configures and displays “200100 bytes”.
The MBS value in bytes is converted automatically to the number of buffers. The conversion
calculation uses a non-configurable buffer size of 2304 bytes or 512 bytes, depending on the
type of adapter card. See Table 4 for a list of adapter cards and their associated buffers. The
calculation is:
Number of buffers = Configured MBS value in bytes / Buffer size in bytes (2304 or 512)
At the egress of an N > 1 Apipe, the MBS value in a SAP egress QoS policy that is assigned
to a SAP aggregation group is used for each of the per-SAP queues for SAPs that are
members of a SAP aggregation group. See the show pools command for information about
how to view buffer pools for SAPs that are members of a SAP aggregation group. See the
7705 SAR Services Guide for information about how to configure SAP aggregation groups.
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.
Note: For the 7705 SAR, 1 kbyte of buffer management space is 1000 bytes.
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