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Quality of Service (QoS): Managing Bandwidth More Effectively
Introduction
Classifiers for Prioritizing Outbound Packets
You can configure QoS prioritization on the basis of seven QoS classifiers, or
packet criteria, evaluated in the following order:
Precedence QoS Classifier
UDP/TCP Application Type (port)
Device Priority (destination or source IP address)
IP Type of Service (ToS) field (IP packets only)
Protocol Priority (IP, IPX, ARP, DEC LAT, AppleTalk, SNA, and NetBeui)
VLAN Priority
Incoming source-port on the switch
Incoming 802.1p Priority (present in tagged VLAN environments)
If the switch is configured with multiple classifiers that address the same
packet, the switch uses only the QoS configuration for the QoS classifier that
has the highest precedence. (In this case, the QoS configuration for another,
lower-precedence classifier that may apply is ignored.) For example, if QoS
assigns high priority to “red” VLAN packets, but normal priority to IP packets,
since Protocol Priority (4) has precedence over VLAN priority (5), IP packets
on the “red” VLAN will be set to normal priority. See
Table 15-4. "Precedence
Criteria for QoS Classifiers" on page 15-9 for more information.
No t e On Us in g HP recommends that you configure a minimum number of the available QoS
M u l tipl e
classifiers for prioritizing any given packet type. Increasing the number of
Cr ite ria
active classifier options for a packet type increases the complexity of the
possible outcomes.
15-8