[MUD-Dev] MMORPG/MMOG P2P design

Ben Hoyt Ben.Hoyt at SilverPlatterSoftware.com
Mon Mar 3 17:45:05 New Zealand Daylight Time 2003

From: Derek Licciardi

> 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.
Very good questions.  First, you're absolutely correct that
bandwidth is the primary concern with a system like this.  However,
with even a modest percentage of users on broadband, you can run the
entire system on their machines and essentially allow modem users to
act as leeches.  We have designed the system in a way to minimize
bandwidth load on the broadband users, as well, by limiting the
number of other clients that any given client has to talk to and
keeping the majority of communications in the form of lightweight
cryptographic hashes that are used for voting.

> 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.
Sorry, there was a miscommunication.  The CS manages login/logoff
(NOT logging).  The majority of logging is handled by the virtual
servers, composed of peer computers, which can filter what gets sent
to the CS.  You're absolutely correct, though, the bandwidth is a
major expense for current MMP games and it is actually the primary
value that our system offers.  We estimate that we can reduce
bandwidth load on the central server by more than 70%.

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