QoS has a dual-role in rich-media WAN and branch networks:
To manage packet loss (and jitter) by queuing policies
To enhance classification granularity by leveraging deep packet inspection engines.
The effect of packet loss on real-time applications has already been discussed at length. However, packet jitter (which is most apparent at the WAN/branch edge because of the dramatic downshifts in link speeds) can result in similar effects on voice and video quality.
Jitter is ...