Quality of Service (QoS): Managing Bandwidth More Effectively

Introduction

N o t e O n U s i n g M u l t i p l e

C r i t e r i a

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

1UDP/TCP Application Type (port)

2Device Priority (destination or source IP address)

3IP Type of Service (ToS) field (IP packets only)

4Protocol Priority (IP, IPX, ARP, DEC LAT, AppleTalk, SNA, and NetBeui)

5VLAN Priority

6Incoming source-port on the switch

7Incoming 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 15-9for more information.

HP recommends that you configure a minimum number of the available QoS classifiers for prioritizing any given packet type. Increasing the number of active classifier options for a packet type increases the complexity of the possible outcomes.

15-8