GS108T and GS110TP Smart Switch Software Administration Manual
B-8 Configuration Examples
v1.0, April 2010
The DiffServ feature contains a number of conceptual QoS building blocks you can use to
construct a differentiated service network. Use these same blocks in different ways to build other
types of QoS architectures.
There are 3 key QoS building blocks needed to configure DiffServ:
• Class
• Policy
• Service (i.e., the assignment of a policy to a directional interface)
Class
You can classify incoming packets at layers 2, 3 and 4 by inspecting the following information for
a packet:
• Source/destination MAC address
• EtherType
• Class of Service (802.1p priority) value (first/only VLAN tag)
• VLAN ID range (first/only VLAN tag)
• Secondary 802.1p priority value (second/inner VLAN tag)
• Secondary VLAN ID range (second/inner VLAN tag)
• IP Service Type octet (also known as: ToS bits, Precedence value, DSCP value)
• Layer 4 protocol (TCP, UDP etc.)
• Layer 4 source/destination ports
• Source/destination IP address
From a DiffServ point of view, there are two types of classes:
• DiffServ traffic classes
• DiffServ service levels/forwarding classes
DiffServ Traffic Classes
With DiffServ, you define which traffic classes to track on an ingress interface. You can define
simple BA classifiers (DSCP) and a wide variety of multi-field (MF) classifiers:
• Layer 2; Layers 3, 4 (IP only)
• Protocol-based
• Address-based
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