Application-Specific QoS Requirements
Not only voice service has QoS needs; other applications and services have their own QoS requirements. The following list is a brief representative sample:
Web access: Needs to be reasonably responsive to maintain user attention
Email: Needs to be in the range of seconds to minutes (at most)
Streaming services (video, music): Need a defined QoS level for usability
Video-over-IP: May be even more stringent than VoIP
Even though a given service may be allocated just "best effort QoS" (i.e., basic IP), this model may merely reflect the fact that most other applications are in the same category. In other words, we all sink or swim together! As applications begin to be differentiated, this model may well become problematic. An obvious example is online security trading, in which timing is crucial and may mean the difference between making and losing money. Online brokerages provide browser-based client access to their systems, so the element of timeliness becomes critical. An important point here is that if more resources are reserved for one service, other services may suffer.