Unforunately latency is something we still need to deal with as it so unpredictable.

As far as VoIP. Sure it doesn’t work behind NAT, put it infront of your NAT. Problem solved. As far as controlling devices behind the NAT. That can be mostly solved with a proxy.

That said, some examples of limits of asymmetrical links are easy. 64Kbits/s (or less in some cases) upstream and 6Mbit/s downstream doesn’t really work if we want to use peer-to-peer applications. That tiny upstream pipe gets filled very easily. Take something like video conferencing or audio conferencing. These are symmetric and synchronous applications. We don’t want the *smart* network caching these real-time packets and attempting to *fix* them or *retransmit* them. By the time a real-time packet gets re-transmitted, it is old and of no use to the real-time stream.

As computing horsepower grows and gets cheaper, it makes sense to push more things to the edge. It makes sense for something like distributed audio-conferencing for instance, where there is no central server and the end-nodes each do their own mixing. However, we cannot do that because the massivley asymmetric last-mile pipes forbid it.

As for NAT (home routers), individual nodes are no longer individually addressable. Always-on applications/devices (such as VoIP phones) are a nightmare to make work with NAT. Beyond phones, what about when we want to address the sprinkler system, the refridgerator, or the garage doors (see GarageBot on this blog http://www.toyz.org/mrblog/archives/00000133.html)?