[MUD-Dev] MMORPG/MMOG P2P design

Derek Licciardi kressilac at insightbb.com
Wed Feb 26 10:34:28 New Zealand Daylight Time 2003

From: Ben Hoyt
> From: Felix A. Croes

> The key in a P2P MMOG system is to assume that you can't trust any
> of the peers.  It is possible, however, to design a system in
> which you can trust the results of execution that is done by the
> peers as a group, without trusting the individual peers
> themselves.

> Basically, you make sure that no individual player at any given
> time has enough authoritative control that they could arbitrarily
> alter the game world.  In other words, the players are constantly
> double-checking each other.  Additionally, no player is ever
> responsible for executing game data that is pertinent to his own
> game experience.  Thus, in our system, you can trust players you
> don't know and you can allow players that you explicitly don't
> trust, to play the game.  This basic paradigm allows you to answer
> your questions 1 and 2.  I'm not really sure what you're getting
> at with #3.  Please elaborate.

> Of course, our system isn't 100% p2p, either.  It's a hybrid, with
> a small centralized component, which enables you to do a LOT in
> the way of authentication, login, establishing trust, tracking
> player resources/behavior, auditing/managing the system.  In the
> end, establishing trust in a hybrid system is really quite doable.

With all of this double checking and such, your bandwidth
requirements are going to go through the roof as each client sends
network messages to and from each other for the sole purpose of
validating the simulation.  I'd think you'ld run into major lag
problems on the upstream side of many player's connections.  Some of
them simply do not have the upstream to be any sort of a reliable
server.  If the simulation depends upon them then you'll get lag.
The other alternative is to make sure that it never depends on any
one peer for a game calculation but then your duplicating bandwith.

If you have a central server taking care of all the logging and
admin tasks, how are you planningon keeping up with the bandwidth
requirements for that server?  Both the upstream and the downstream
is going to be larger than any MMO game out there today and the
expense of a fat pipe is typically one of the largest expenses this
side of human resources.  As with any distributed system, I can see
the bottleneck being in the communication between clients.  I
wouldn't jump to its going to work and is quite doable until you see
hard proof that it works on the scale your attempting.


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