User`s guide

HTML SET UP & DIAGNOSTIC
Failsafe ring SHDSL switch User’s guide ref 9014809-03 Page 43
15 Quality of service (QoS) set up
15.1 DiffServ benefits & overview
The goal of Quality of Service algorithms is to guarantee that critical data
flows will be transmitted with lower delay than others.
For instance, it can be difficult to transmit on the same SHDSL network an
important video data flow and a small but critical PLC protocol data flow.
To solve that question, the XSRING implements the DiffServ algorithm.
• Terms definitions
A service is the association of a protocol (TCP, UDP, ICMP, AH, ESP, GRE, IGMP) and a
port number; for instance TCP and port 502.
A target is a range of IP addresses (IP address plus netmask); for instance 192.168.1.0 /
255.255.255.0 .
A traffic is a particular data flow defined by a particular target and a particular service.
• Classes :
5 traffic classes are defined : Premium, Gold, Silver, Bronze, Default (or Best effort).
The Premium class is the class which will be transmitted with the first
priority. The default class will be transmitted with the last priority.
A minimum and a maximum bandwidth are assigned to each class.
The bandwidth of the Premium class is not limited.
An example is given hereafter :
Minimum bandwidth Maximum bandwidth
% of the whole bandwidth % of the whole bandwidth
CLASSES :
Premium - unlimited
Gold 20 % 30 %
Silver 15 % 20 %
Bronze 10 % 15 %
Default 5 % unlimited
Total 60 %