[Nel] TCP vs. UDP

Sun, 8 Jul 2001 18:44:09 +0200

I've been reading this thread with great interest.  There's clearly a good
+case for using UDP for low priority or short life-span data.  In this case
+the app software on top of NeL must clearly be designed with the fact that
+some data isn't going to get through in mind.
+
+The problem is particularly interesting because:
+1. The limiting factor on the amount of data we transmit looks like being
+the cost of output bandwidth for the servers.
+- as far as I can ascertain, at today's costs we're looking at something
+like 8-16 kilobits per client per second maximum output from the servers
+(including lost packets)
+2. The complexity of the scenes that we are trying to convey to the clients
+is rising fast.
+- view distances are increasing, as are screen resolutions which means that
+you can see more dynamic world content at any given time (characters,
+creatures, objects...)
+- It is clear that for MMORPGs we wil soon need to be able to display crouds
+or armies of 100s or even 1000s of characters and creatures at once.
+- Character animation is becoming more complicated to reflect a mix of
+actions performed simultaneously (such as speaking with emotional facial
+expression and manipulating an object in one's hands while sitting down) -
+which means more information to describe each character's state.
+- and so on...
+
+These two points combined mean that, whichever way one looks at it, a lot of
+scene information will have to be filtered out or sent at low frequency.  If
+one isn't careful low frequency sends can obviously be very sensitive to
+packet loss - which leads me to the point of this posting: In order to work
+the problem we need to have a good understanding of true internet behaviour
+and to have a good set of test data for simulating it.
+
+The trouble right now is that I have no hard data to use to model packet
+loss or delivery latency over time. If anybody knows of any studies that
+have been done or has any of their own data I'd be very interested. In
+particular I'm interested in moderately bad connections that exhibit both
+good behaviour and bad behaviour over time.
+
+Regards to all,
+Daniel
+
+
+
+