Configuring Class Setup; Table 20-10 Diffserv: Differentiated Service Field; Table 20-11 Sub-Classes Of The Af Service - ZyXEL Communications Prestige 652H series User Manual

The DSCP value determines the forwarding behavior, the PHB (Per-Hop Behavior), that each packet gets
across the DiffServ network. Based on the marking rule, different kinds of traffic can be marked for different
kinds of forwarding. Resources can then be allocated according to the DSCP values and the configured
policies.
PHB consists of two types of services: EF (Expedited Forwarding) and AF (Assured Forwarding). EF has
higher priority. EF guarantees services with minimal loss and delay. AF has four sub-classes, each with three
levels of importance (drop precedence). A high drop precedence means low importance.
DiffServ PRIORITY
SUB-CLASS 4
SUB-CLASS 3
SUB-CLASS 2
SUB-CLASS 1

20.10 Configuring Class Setup

The class setup screen displays the configured bandwidth classes by individual interface. Select an interface
and click the buttons to perform the actions described next. Click "+" to expand the class tree or click "-" to
collapse the class tree. Each interface has a permanent root class. The bandwidth budget of the root class is
equal to the speed you configured on the interface (see section 20.8 to configure the speed of the interface).
Configure child-class layers for the root class.
To add or delete child classes on an interface, click BW Manager, then Class Setup. The screen appears as
shown (with example classes).
The example reserves 10 Mbps of unbudgeted bandwidth for traffic that is not defined in the bandwidth
filters (see section 20.6.1). The Administration and Sales USA bandwidth classes each have bigger
bandwidth budgets than the total of the budgets of their child-classes. The child-classes can borrow the extra
bandwidth as long as they have bandwidth borrowing enabled (see section 20.7).
Bandwidth Management
DSCP
(6-bit)

Table 20-10 DiffServ: Differentiated Service Field

Table 20-11 Sub-Classes of the AF Service

LOW DROP
PRECEDENCE
AF41
AF31
AF21
AF11
Prestige 652H/HW Series User's Guide
Unused
(2-bit)
MEDIUM DROP
PRECEDENCE
AF42
AF32
AF22
AF12
HIGH DROP
PRECEDENCE
AF43
AF33
AF23
AF13
20-11