5-82
Quality of Service: Managing Bandwidth More Effectively
Advanced Classifier-Based QoS
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 described in “Globally-Configured QoS” on page
5-16.
If you use a classifier-based QoS configuration along with globally-configured
QoS commands, the order of precedence in which 802.1p priority, IP prece-
dence, and DSCP settings mark selected packets is as follows, from highest
(1) to lowest (9):
Table 5-10. Order of Precedence for Classifier-Based QoS over Global QoS
Precedence
Order
QoS Feature Reference
1 Classifier-based port-specific policy Page 5-72
2 Classifier-based VLAN-specific policy Page 5-72
3 Globally-configured TCP/UDP priority Page 5-21
4 Globally-configured IP-device priority Page 5-32
5 Globally-configured IP Type-of-Service priority Page 5-40
6 Globally-configured Layer 3-Protocol priority Page 5-53
7 Globally-configured VLAN-ID priority Page 5-55
8 Globally-configured Source-Port priority Page 5-62
9 802.1p CoS in Layer 2 VLAN header
1
Page 5-9
1
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.
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