igor2930 Series User’s Guide 
103
In a QoS-enabled network, or Differentiated Service (DiffServ or DS) framework, a DS 
domain owner should sign a Service License Agreement (SLA) with other DS domain 
owners to define the service level provided toward traffic from different domains. Then each 
DS node in these domains will perform the priority treatment. This is called 
per-hop-behavior (PHB). The definition of PHB includes Expedited Forwarding (EF), 
Assured Forwarding (AF), and Best Effort (BE). AF defines the four classes of delivery (or 
forwarding) classes and three levels of drop precedence in each class. 
Vigor routers as edge routers of DS domain shall check the marked DSCP value in the IP 
header of bypassing traffic, thus to allocate certain amount of resource execute appropriate 
policing, classification or scheduling. The core routers in the backbone will do the same 
checking before executing treatments in order to ensure service-level consistency throughout 
the whole QoS-enabled network. 
However, each node may take different attitude toward packets with high priority marking 
since it may bind with the business deal of SLA among different DS domain owners. It’s not 
easy to achieve deterministic and consistent high-priority QoS traffic throughout the whole 
network with merely Vigor router’s effort. 
In the 
Bandwidth Management 
menu, click 
Quality of Service
to open the web page. 
This page displays the QoS settings result of the WAN interface. Click the 
Setup 
link to 
access into next page for the general setup of WAN (1/2) interface. As to class rule, simply 
click the 
Edit 
link to access into next for configuration. 
You can configure general setup for the WAN interface, edit the Class Rule, and edit the 
Service Type for the Class Rule for your request. 
General Setup for WAN Interface 
When you click 
Setup
, you can configure the bandwidth ratio for QoS of the WAN interface. 
There are four queues allowed for QoS control. The first three (Class 1 to Class 3) class rules 
can be adjusted for your necessity. Yet, the last one is reserved for the packets which are not 
suitable for the user-defined class rules.