Delay is a crucial cause of VoIP quality degradation, and many other causes are highly interdependent with delay. Therefore, delay must be reduced by improving the routing in the network or by reducing the processing time within the endpoints and intermediate nodes.
For example, when delay is minimized:
Jitter and electrically induced echo abate.
Intermediate node and jitter buffer resources are released making packet loss insignificant.
As packets move faster in the network, the resources at each node are available for the next packet that arrives. Packets are not dropped because of lack of resources.
Delay cannot be eliminated completely from VoIP applications because delay includes the inevitable processing time at the endpoints plus the transmission time. However, the delay that is caused because of network congestion or queuing can be minimized by adjusting the following Quality of Service (QoS) parameters:
Layer 3 QoS
DiffServ
RSVP
Layer 2 QoS: 802.1p/Q
These parameters are administered on the IP Network Region screen. See IP network regions.
