User guide

EDA System Services
52 1/1551-HSC 901 35/3 Uen C 2005-12-02
Classification
Classification
Classification
Classification
IP Network
PSTN/ISDN
network
Ethernet
Access Domain
Classification
PoP
PoP
Access
node
Voice
Gateway
Access
node
Edge
Router
Ethernet
Switch
Figure 38 Traffic Classification in an EDA Network
6.2.2 Traffic Handling
The principle of differentiated services is that every single switch or router,
as an autonomous unit, decides the order, in which packets or frames are
forwarded on the transmission link. The decision is based on the
classification (p-bit) of the packet or frame, and the QoS policy.
The differentiated services implementation used in the Ethernet is
according to the IEEE 802.1Q specification, specifying 8 values using three
bits, the so called p-bit. The p-bit value indicates the classification of the
frame.
Figure 39 on page 53 illustrates the operation of a differentiated services
based forwarding process of a network element using two priority levels
(Classes of Service), one for voice and one for data.