Override of global QoS settings
After you apply a QoS policy to an interface, the classifier-based settings configured by QoS actions in the policy override any 802.1p CoS or DSCP codepoint values that were globally-configured on the switch to mark packets using the QoS commands.
If you use a classifier-based QoS configuration along with globally-configured QoS commands, the order of precedence in which 802.1p priority, IP precedence, and DSCP settings mark selected packets is as follows, from highest (1) to lowest (9):
Precedence order |
QoS feature |
---|---|
1 |
Classifier-based port-specific policy |
2 |
Classifier-based VLAN-specific policy |
3 |
Globally-configured TCP/UDP priority |
4 |
Globally-configured IP-device priority |
5 |
Globally-configured IP Type-of-Service priority |
6 |
Globally-configured Layer 3-Protocol priority |
7 |
Globally-configured VLAN-ID priority |
8 |
Globally-configured Source-Port priority |
9 |
802.1p CoS in Layer 2 VLAN header1 |
In a tagged VLAN environment, the incoming 802.1p priority is used as the default QoS classifier to determine how a packet is handled if no global or classifier-based QoS match criterion with a higher precedence matches.