Bandwidth Settings Recommendations
In earlier VROC versions, we recommended use of a core.ini
file to race online. The host can now control communications
settings to best advantage by checking "Use recommended
bandwidth." Using these recommendations
is likely to allow more players to join the race, and will reduce
disconnects and other unpleasant phenomona.
Specifically, we send command line arguments that set the
net_mdm_client_send_every = 3
net_mdm_client_send_size = 84
net_mdm_server_send_every = 3
net_mdm_server_send_size = 84
disable_modem = 1
This creates the same effect as do equivalent core.ini settings,
and in fact overrides (but does not overwrite) core.ini in this
respect. For your convenience, we also disable the modem poll
at startup, which speeds up loading of the game.
According to the information on the wonderfully informative
web site of Bart Westra, this will give the following
Client: upload 9.9Kb/s, download 13.2Kb/s
Server (3 clients): upload 39.8Kb/s, download 25.9Kb/s
Server (5 clients): upload 66.2Kb/s, download 43.2Kb/s
Server (8 clients): upload 106.1Kb/s, download
Server (12 clients): upload 159.0Kb/s, download
Server (16 clients): upload 212.0Kb/s, download
This suggests that a 64kb ISDN modem should be able to handle
4 clients reliably, and that a 112 or 128kb ISDN modem should
be able to handle 8 clients reliably. Cable and xDSL will depend
on the available upload speed; anything over about 270kb should
be able to handle a full field of 20 players.
Clearly, it's pushing it to try to host three clients on an
analog modem, since even 56kb analog modems have a maximum of
Of course, these numbers are theoretical and each host must
establish their own practical maximum through experience.
Why use bandwidth settings?
Reducing the bandwidth reduces the load on the serial port.
If your CPU cannot keep up with the data coming into and going
out of the serial port, important information is lost. If too
much information is lost, the sim decides that the connection
quality is too poor for racing, and disconnects.
Besides checking out Bart's site, the more technically inclined
may click here
to download a zip file containing several core.ini files and
a ReadMe file with a detailed explanation of core.ini parameters.
See also Eagle Woman's GPL
Online FAQ for more information about bandwidth, core.ini,
and other online racing topics.