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Quality of Service (QoS): Managing Bandwidth More Effectively 
Introduction 
Classifiers for Prioritizing Outbound Packets 
The classifiers used in the 3400cl/6400cl switches are a subset of the classifiers 
used in the 5300xl switches. Also, the 3400cl/6400cl switches search for 
classifier matches in the opposite order of that used in the 5300xl switches. 
Note  On Using  HP recommends that you configure a minimum number of the available QoS 
Multiple 
classifiers for prioritizing any given packet type. Increasing the number of 
Criteri a 
active classifier options for a packet type increases the complexity of the 
possible outcomes and consumes switch resources. 
5300xl Packet Classifiers and Evaluation Order 
The 5300xl switches provide seven QoS classifiers (packet criteria)  you can 
use to configure QoS priority. 
Table 8-4.  5300xl Classifier Search Order and Precedence 
Search 
Order 
Precedence  QoS Classifier Type 
1 (highest) 
UDP/TCP Application Type (port) 
2 
Device Priority (destination or source IP address) 
3 
IP Type of Service (ToS) field (IP packets only) 
4 
Protocol Priority (IP, IPX, ARP, DEC LAT, AppleTalk, SNA, and NetBeui) 
5 
VLAN Priority 
6 
Incoming source-port on the switch 
7  (lowest) 
Incoming 802.1p Priority (present in tagged VLAN environments) 
Where multiple classifier types are configured, a 5300xl switch uses the 
highest-to-lowest search order shown in table 
8-4 to identify the highest-
precedence classifier to apply to any given packet. When a match between a 
packet and a classifier is found, the switch applies the QoS policy configured 
for that classifier and the packet is handled accordingly. 
Note that on a 5300xl switch, if the switch is configured with multiple classi-
fiers 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 packets belonging to 
VLAN 100, but normal priority to all IP protocol packets, since protocol 
priority (4) has precedence over VLAN priority (5), IP protocol packets on 
VLAN 100 will be set to normal priority. 
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