UDP vs. TCP distribution [was: Re: [e2e] Can feedback be
T.Henderson at cs.ucl.ac.uk
Mon Mar 5 09:54:38 PST 2001
In message <20010305162541.5E74F8A3 at sean.ebone.net>, Sean Doran said:
>Mmmm, socio-psychology meets networking. Always fun, never understood fully.
>| It would be useful to know the absolute highest delays that gamers can
>Surely this will be somewhat application-dependent?
Yes, you'd expect (within networked games) that delay requirements would look
like shoot-em-up < RPG < chess. It should be possible, however, to come up
with some general figures, a G.114 equivalent for shoot-em-ups. I'd just like
something more concrete than figures pulled out of a hat, so if anyone knows
of any (reasonably) scientific studies please point me at them.
>However, there's probably some literature here and there about
>human reflexes and how fast one needs a result back from a "twitch"
>in order to feel reasonably interactive. Probably very little
>of that will focus on network impact.
Precisely. There is stuff in the VR and physiology worlds about reflexes, but
it's not clear that this applies to the Internet, where people seem to put up
with a lot more than they'll admit to in a lab experiment.
>| >FWIW, network games are fascinating examples of interactive applications.
>They're also fun. I've never been big into shoot-em-up games,
>since building the Internet is faster and harder, but some friends
>had me over to play Unreal Tournament with their clan the other week,
>and my eyes were opened a bit. UT in any event was more sensitive
>to loss and "drop outs" than to stable delay -- for me, anyway, choppy
>updates and missed action was more important and harder to compensate
>for than aiming ahead along the direction the target is seen to be moving.
Interesting. I've been concentrating on Half-Life mainly (it seems to be the
most widely-played game according to tracking sites such as
http://www.theclq.com/games.asp) but I might have to give UT a go as well.
>| 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.
>It turns out that LAN parties are pretty common: people drive across
>Europe to gather together around a hub or small switch, matching up
>as teams in a series of competitions within a broader league.
But this isn't always an option for geographically dispersed groups, so a lot
of games server operators allow clans to book servers for private games.
That's why I'd quite like to determine the QoS requirements for applications
such as these; games players are already spending lots of money on their
habit, so they should be quite receptive to paying for QoS.
>| Alas, games seem to have been neglected by the networking
>| research community, but hopefully that is changing.
>Heh - well, they're sure popular among operators, at least those
>on the operations front, as far as I can tell. Perhaps that is
>a reflection of a dichotomy between people who are reactive & practical
>versus people who like to plan in advance and understand the theory
No comment :)
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