UDP vs. TCP distribution [was: Re: [e2e] Can feedback be generated...]

[Tristan Henderson]

In message <3AA08A3E.541D233 at ehsco.com>, "Eric A. Hall" said:
>
>People don't play action-oriented multi-player games over long-haul
>networks. Shoot-em-up games are very sensitive to latency and packet loss.
>Playing a shoot-em-up with >200ms RTT will get you killed fast by players
>with <20ms (client-side events have to wait for server-side messages to
>arrive so the "closer" player gets a distinct advantage in terms of
>shorter inter-command gap). After a while, you learn to play on servers
>that are close.
>

Do you have any data/stats to support these figures? I'm doing some analysis 
of shoot-em-up games and haven't been able to find anything authoritative 
about the maximum delays for networked games. I've seen figures of ~200ms 
being declared as the "maximum" delay before; e.g. a games designer says that 
they design for 200-300ms delays at http://www.gamasutra.com/features/19970905/
ng_01.htm.

OTOH, there are plenty of usenet postings from people playing with RTTs of 
300-1000ms, e.g.
http://groups.google.com/groups?hl=en&lr=&safe=off&ic=1&th=1daccce21a879875
http://groups.google.com/groups?hl=en&lr=&safe=off&ic=1&th=2cd5a305b3152d89
http://groups.google.com/groups?hl=en&lr=&safe=off&ic=1&th=41803c558ae2df07

(apologies if these google links don't work; I haven't quite got used to their 
usenet archive yet)

It would be useful to know the absolute highest delays that gamers can 
tolerate.
 
>
>FWIW, network games are fascinating examples of interactive applications.

I agree. I'm particularly interested in the multiuser aspects - for example, 
as you state, there are dynamics which may force users with similar network 
characteristics to congregate together. Alas, games seem to have been 
neglected by the networking research community, but hopefully that is changing.

Cheers,
Tristan