Quality of Service (QoS): Managing Bandwidth More Effectively  
Using QoS Classifiers To Configure QoS for Outbound Traffic 
QoS Source-Port Priority 
QoS Classifier Precedence: 6 
The QoS source-port option enables you to use a packet’s source-port on the 
switch as a QoS classifier. Where a particular source-port classifier has the 
highest precedence in the switch for traffic entering through that port, then 
traffic received from the port is marked with the source-port classifier’s 
configured priority level. Different source-port classifiers can have different 
priority levels. 
Options for Assigning Priority.  Priority control options for packets from 
a specified source-port include: 
■  802.1p priority 
■  DSCP policy (Assigning a new DSCP and an associated 802.1p priority; 
inbound packets must be IPv4.) 
(For operation when other QoS classifiers apply to the same traffic, refer to 
“Classifiers for Prioritizing Outbound Packets” on page 6-9.) 
Assigning a Priority Based on Source-Port 
This option assigns a priority to outbound packets having the specified source-
port. Configure this option by either specifying the source-port ahead of the 
qos command or moving to the port context for the port you want to configure 
for priority. (For configuring multiple source-ports with the same priority, you 
may find it easier to use the interface < port-list > command to go to the port 
context instead of individually configuring the priority for each port.) 
Syntax:  interface < port-list > qos priority < 0 - 7 > 
Configures an 802.1p priority for packets entering the switch 
through the specified (source) ports. This priority determines 
the packet queue in the outbound port(s) to which traffic is 
sent. If a packet leaves the switch on a tagged port, it carries 
the 802.1p priority with it to the next downstream device. You 
can configure one QoS classifier for each source-port or group 
of source-ports. (Default: 
No-override) 
no interface < port-list > qos 
Disables use of the specified source-port(s) for QoS 
classifier(s) and resets the priority for the specified source-
port(s) to 
No-override. 
show qos port-priority 
Lists the QoS port-priority classifiers with their priority data. 
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