3Com 4007, Руководство по внедрению, Страница: 576 / 684

576 C
HAPTER
22: Q
O
S
AND
RSVP
Assigning Flow and
Nonflow Classifier
Numbers
Each classifier requires a unique number in the range of from
1 through 498. When you define a classifier, the first information you
supply is the classifier number. The number you specify dictates which
type of classifier you are defining.
Default
The default classifier number is 499, which you cannot remove or modify,
because all traffic that passes through the QoS engine and the Multilayer
Switching Module needs a default classifier to handle all packets.
■
To define a flow classifier (for routed IP packets only), specify a value in
the range of from
1
through
399
. This setting allows you to specify IP
source or destination addresses (or both) as well as TCP or UDP socket
information.
■
To define a nonflow classifier (for bridged or routed packets), specify a
value in the range of from
400 through 498 . (See the list of
predefined nonflow classifiers in Figure 66.) For nonflow classifiers,
you cannot classify to the IP address or socket level.
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 can use two classifiers as follows:
■
You define a flow classifier with classifier number 6, which recognizes
all TCP or UDP traffic from IP address 3.3.3.3. The control that 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, because classifier number 6 is lower than classifier
420 and has a higher precedence. Table 93 shows the basic information
for these classifiers.
Table 93 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