I see no "of course." Are there some applications which require this
level of service in a WAN? Probably. Are there many? Probably not.
Is end-to-end relability and performance more important for the *vast*
majority of applications? Yes!
I'll concede the fact that the number of 'surf the net' applications
far exceed the number of real-time systems in the Internet.
But, we am working on a WAN project that required real time data delivery
every few seconds across the US to numerous sites. Even though the
numbers are few *today* they do exist and are growing in number and
complexity. In fact, there are numerous applications and system
designs just waiting for the 'network to support real-time services.'
Just because real-time services are in the minority of datagram services,
does not translate to 'the world should not support real-time services'.
If that is the logic that is used to make decisions, then let's
stop funding libraries because the vast majority get their information
Real-time WAN services with concrete .99999+ availability of QoS is
one of the growth areas of the next decade, BTW, and is a much
differnet service that providing access so 'Joe&Judy surf-the-net'
can pull down yet another file.
There are numerous applications for real-time datagram delivery
systems. ATM may not be the underlying transport, as mentioned;
but there is an emerging market for .99999+ datagram services.
The average IP provider may never see this market, but believe
me, they exists.