3Com CoreBuilder 3500, Руководство по внедрению, Страница: 485 / 592

QoS Classifiers 485
The classifier number indicates precedence. The classifier with the lowest
number takes precedence if a packet meets the criteria for more than one
classifier.
For example, you might use two classifiers as follows:
■
You define a flow classifier with classifier number 6 that recognizes all
TCP or UDP traffic from IP address 3.3.3.3. The control you assign to
this classifier (control 5) gives this traffic a
low priority service level.
■
You use the predefined nonflow classifier 420, which recognizes all
TCP traffic, and create a control for this classifier to give the TCP traffic
a
high priority service level. (By default, this classifier has no control.)
With these classifiers in place, if 3.3.3.3 sends TCP traffic, this traffic
receives
low priority, since classifier number 6 is lower than classifier 420
and has a higher precedence. Table 60 shows the basic information for
these classifiers.
Defining Flow
Classifiers
You can define up to 100 flow classifiers per system for routed IP traffic.
When you define a flow classifier (using a unique classifier number), you
can create one or more address/port patterns (filters) for that classifier.
Each address/port pattern counts toward the flow classifier limit.
Therefore, if you define a flow classifier with 10 address/port patterns,
you can have up to 90 additional flow classifiers.
Because a flow classifier handles IP routed traffic only, it is expected that
you have an IP VLAN, an IP routing interface, and IP routing enabled.
Table 60
Classifier Number Precedence for Two Classifiers
Classifier Name Control Cast Protocol 802.1p
6
(user-defined) from_3.3.3.3 5
(for low priority)
UM all (TCP,
UDP) –
420
(predefined) TCP/IP 6
(for high priority)
U TCP/IP 0-7