Allied Telesis AT-S62 - Manual (Page 260)

Chapter 16: Quality of Service
Section II: Advanced Operations 260
A simple example of this process is shown in Figure 82, for limiting the
amount of bandwidth used by traffic from a particular IP address. In the
domain shown, this bandwidth limit is supplied by the class of service
represented by a DSCP value of 40. In the next DiffServ domain, this
traffic is assigned to the class of service represented by a DSCP value of
3.
Figure 82 DiffServ Domain Example
To use the QoS tool set to configure a DiffServ domain:
1. As packets come into the domain at edge switches, replace their
DSCP value, if required.
Classify the packets according to the required characteristics. For
available options, see Chapter 14, Classifiers on page 219.
Assign the classifiers to flow groups and the flow groups to traffic
classes, with a different traffic class for each DiffServ code point
grouping within the DiffServ domain.
Give each traffic class the priority and/or bandwidth limiting
controls that are required for that type of packet within this part
of the domain.
Assign a DSCP value to each traffic class, to be written into the TOS
field of the packet header.
Non-DiffServ
traffic
Classify by source IP address
Mark with DSCP=40
Limit bandwidth
DiffServ Domain
Classify by DSCP=40
Limit bandwidth
Classify by DSCP=40
Limit bandwidth
Re-mark to DSCP=3
Next DiffServ
domain