Assigning a DSCP policy based on the source-port
This option assigns a previously configured DSCP policy (codepoint and 802.1p priority) to outbound IP packets (received from the specified sourceports). That is, the switch:
- Selects an incoming IP packet on the basis of its source-port on the switch.
- Overwrites the packet’s DSCP with the DSCP configured in the switch for such packets.
- Assigns 802.1p priority configured in the switch for the new DSCP (see Differentiated Services Codepoint (DSCP) mapping).
- Forwards the packet through the appropriate outbound port queue.
Steps for creating a policy based on source-port classifier:
You can select one DSCP per source-port. Also, configuring a new DSCP for a source-port automatically overwrites (replaces) any previous DSCP or 802.1p priority configuration for that port.)
Identify the source-port classifier to which you want to assign a DSCP policy.
- Determine the DSCP policy for packets having the selected source-port:
Determine the DSCP you want to assign to the selected packets. (This codepoint will be used to overwrite the DSCP carried in packets received through the source-port from upstream devices.)
Determine the 802.1p priority you want to assign to the DSCP.
Configure the DSCP policy by using
qos dscp-map
to configure the priority for each codepoint (see Differentiated Services Codepoint (DSCP) mapping for more information).Configure the switch to assign the DSCP policy to packets from the specified source-port.
Syntax:
interface <port-list> qos dscp <codepoint>
Assigns a DSCP policy to packets from the specified sourceports, and overwrites the DSCP in these packets with the assigned
<codepoint>
value. This policy includes an 802.1p priority and determines the packet’s queue in the outbound port to which it is sent. If the packet leaves the switch on a tagged port, it carries the 802.1p priority with it to the next downstream device.
(Default:
No-override
)
Syntax:
no interface <port-list> qos
Removes QoS classifier for the specified source-ports.
Syntax:
show qos port
Displays a listing of all source-port QoS classifiers currently in the running-config file.
Source-port |
DSCP |
Priority |
---|---|---|
2 |
15 |
7 |
1, 3 |
16 |
5 |
4, 5 |
17 |
1 |
An example of the completed source-port DSCP-priority configuration is shown below
switch(config)# int 4,5 switch(eth-4,5)# qos dscp 17 switch(eth-4,5)# int 1,3 switch(eth-1,3)# qos dscp 16 switch(eth-1,3)# int 2 switch(eth-2)# qos dscp 15 switch(eth-2)# show qos port-priority Port priorities Port Apply rule | DSCP Priority Radius Override ---- ----------- + ------ ----------- --------------- 1 DSCP | 010000 5 No-override 2 DSCP | 001111 7 No-override 3 DSCP | 010000 5 No-override 4 DSCP | 010001 1 No-override 5 DSCP | 010001 1 No-override 6 No-override | No-override No-override 7 No-override | No-override No-override . . . . . . . . . .