Nortel RLC, Installation And Administration Manual

Page: 239 / 466

RLC Installation and Administration Guide 213
June 2005 Configuring the RLC
Configuring QoS
The slide controls allow 10 settings ranging from poor to superior, within the
following boundaries:
„
1 (poor) equates to a MOS (Mean Opinion Score) value of 3.0, as
calculated by the RLC and based upon the ITU E-Model for serviceability
and service integrity performance
„
10 (superior) equates to a MOS value of 4.0
Since the ITU E-Model uses network delay as its sole point of reference, the
RLC also factors in average packet-loss to obtain the MOS value. For example,
if the user sets the threshold to a MOS value of 3.5 (center tick of slide control),
the following scenario can occur. The measured delay on the network may
indeed be less than a score of 3.5 according to the ITU E-model. However,
excessive packet loss can lower the MOS value calculated by the RLC. In this
scenario, the RLC moves the call from the IP network to the PSTN. This move
ensures an acceptable QoS for the user, based on real network conditions.
QoS configuration procedure
1 Complete the fields as described in “Quality of Service field descriptions”
on page 214.
2 Click on the OK button.
Result: Configuration Manager writes the changes to a temporary file on
the administration PC.
3 Click on the Send button to update the RLC with the new information.
Note: To save changes to the RLC’s Flash memory, select Upload
→
Save
to Flash from the Menu Bar.