Operating instructions

optiClient5d_Installation.fm
A31003-G2550-A100-6-76A9, 04/2005
optiClient 130 V5.0 , Administrator Documentation and Operating Instructions
2-3
Nur für den internen Gebrauch
Installing optiClient 130
Configuring/Installing Quality of Service
2.2 Configuring/Installing Quality of Service
General
optiClient 130 can use the Windows QoS (Quality of Service) Packet Scheduler for controlling
network traffic to improve voice quality in the network. When using this service, telephony pack-
ets are given priority over "normal" data packets in the network. For Windows 2000/XP, the re-
quired QoS features are supported by the operating system. The necessary configuration steps
are described below.
If QoS is to be used, the service must be installed/configured on the optiClient 130 PC.
The following problems may arise during data transfer in an IP network:
● Delays caused by large email attachments and Web surfing
● Network blockages due to multiple requests for the same Web page
● Reduced voice quality caused by
–delays
– jitter
– packet loss
QoS methods
Quality of Service employs different methods to ensure specific transfer properties in packet-
oriented networks (IP).
This is why it is important for Voice over IP, for example, to ensure a minimum bandwidth for the
duration of the transfer operation. If several applications are running simultaneously over IP, the
bandwidth available for a transmission path (for example, an ISDN B channel, 64 Kbps) is di-
vided. This can result in packet loss in a voice connection, which in turn results in reduced voice
quality.
Different types of traffic are transported via a single IP infrastructure in HiPath networks. Quality
of Service aims to satisfy the requirements of data and voice traffic.
Voice traffic must be assigned a high priority to avoid instances where data traffic suppresses
voice traffic. The specifications must also ensure that traffic with higher priority is transferred
before traffic with lower priority. These specifications are made on Layer 2 and 3 of the ISO-OSI
7 Layer model:
● The three bits are used in the 802.1p field on Layer 2. This field is part of 802.1Q-Tag.
● The six bits from the DiffServ Code Point (DSCP) field are used in the Type of Service (ToS)
byte in the IP header on Layer 3.