Advanced Traffic Management Guide K/KA/KB.15.15

4. Forwards the packet through the appropriate outbound port queue.
Creating a policy based on the VLAN-ID classifier
1. Determine the VLAN-ID classifier to which you want to assign a DSCP policy.
2. Determine the DSCP policy for packets carrying the selected VLAN-ID.
a. Determine the DSCP you want to assign to the selected packets. (This codepoint will be
used to overwrite the DSCP carried in packets received from upstream devices.)
b. Determine the 802.1p priority you want to assign to the DSCP.
3. If necessary, use the qos dscp-map codepoint priority 0 - 7 command to configure
the DSCP policy (codepoint and associated 802.1p priority) that you want to use to mark
matching packets.
Prerequisite: A DSCP codepoint must have a preconfigured 802.1p priority (0 - 7) before you
can use the codepoint to mark matching packets. If a codepoint you want to use shows
No-override in the Priority column of the DSCP Policy table (show qos dscp-map
command), you must first configure a priority for the codepoint before proceeding (qos
dscp-map priority command).
4. Configure the switch to assign the DSCP policy to packets with the specified VLAN-ID.
Syntax:
qos dscp-map codepointpriority 0 - 7
This command is optional if a priority has already been assigned to the codepoint.
The command creates a DSCP policy by assigning an 802.1p priority to a specific
DSCP.
When the switch applies this priority to a packet, the priority 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.
For IP packets, the DSCP codepoint in the packet header is replaced by the
codepoint specified in this command.
Default: For most codepoints, No-override.
Syntax:
vlan vid qos dscp codepoint
Assigns a DSCP policy to IP packets carrying the specified VLAN ID, and overwrites
the DSCP in these packets with the assigned codepoint value.
• A binary value for the six-bit codepoint from 000000 to 111111.
• A decimal value from 0 (low priority) to 63 (high priority) that corresponds to
a binary DSCP bit set
• An ASCII standard name for a binary DSCP bit set.
Enter ? to display the list of valid codepoint entries.
The DSCP 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 vlan vid qos
Removes a global QoS classifier for the specified VLAN.
Creating a policy based on the VLAN-ID classifier 211