Cutting down on Bandwidth

[sil3ntwar]

This is something i have been thinking about for awhile now but never mentioned. I just saw the NKPro will have this feature and im not sure if LFS does.

From the server bandwith battlefront there is now a new system to change the frequency of packets based on the client's distances and it really cut down the bandwith a lot.
http://www.drivingitalia.net/forum/index.php?showtopic=24201


I have always thought that if someone is at the back of aston and im on the start finish straight then why would i want to receive their packets as often as someone who is next to me. I havent seen this mentioned anywhere as being implemented in LFS so i thought i would bring it up.

[X-Ter]

There must be several ways of cutting down bandwidth. I race a lot of Nascar Heat (using roadcourse mods of course :) ), and in the "thin" mod I can pack over 30+ vehicles on a 1Mbit upload line. Among the usual drivers on SCORE, there are at least two on dial up, and the rest is on various speed DSL and Cable connections. Still, the racing is as smooth and accurate as anything I've seen so far.

But... I'm not complaining about LFS's netcode. It's far better than most, and it's not even finished yet :)

[_--NZ--_[HUN]]

If you have 1Mbit upload then you could host a game for 30 people in LFS. I can host for 6 racers with a 200 kbit upload so you are able to host for five times more drivers 'cause you have the bandwith for it.

[Kegetys]

The question is would it really do anything that useful? If you or the server do not have the bandwidth to handle all the cars at full rate, then you're going to get into problems right at the race start when everyone is packed up together.

Also, after the race if you would want to look at the replay to see what happened at the other side of the track it would not be very pleasant to watch with a low rate of updates received...

[ajp71]

What does N2003 use, it copes with dial up better than most, and supports 42 cars :)

[X-Ter]

What does N2003 use, it copes with dial up better than most, and supports 42 cars :)
Yes it's good, but Heat is actually even better, and support 43 cars on track :thumb:
If I get a DSL service available here with even faster upload I would like to host a 43 car GT grid :)

--- Edit ---
The thing is... Heat has a "thin" mode as well as a normal mode when hosting. In thin mode you sacrifice two things, witch are brake lights and visible slides (by other vehicles). In thick mode, you can host less cars since there are more strain on the bandwidth, but you also get that extra little bit of information on your opponents.

[joshdifabio]

']If you have 1Mbit upload then you could host a game for 30 people in LFS. I can host for 6 racers with a 200 kbit upload so you are able to host for five times more drivers 'cause you have the bandwith for it.
No, the bandwidth requirement doesn't go up in a linear way, it increases exponentially. Every time you add a car it means you have to send that car packets for every other car, and every other car packets for that car (don't know the technical lingo). So if you add a car when there are only five cars, then those 5 cars each have to be sent 1 more packet, and the new car 5 more packets, so 10 more in total. If there are 20 cars and you add one more, that's 40 more packets to send. Here is a table showing how much bandwidth is required for different numbers of cars:


4 guests, 4 cars : 4.9 KB/s
8 guests, 8 cars : 21.4 KB/s
11 guests, 11 cars : 41.6 KB/s (demo max)
12 guests, 12 cars : 49.9 KB/s
15 guests, 15 cars : 79.1 KB/s (S1 max)
16 guests, 16 cars : 90.4 KB/s
20 guests, 20 cars : 142.9 KB/s
23 guests, 20 cars : 165.9 KB/s (S2 max)

[the_angry_angel]

Theres only one true solution to decreasing the amount of bandwidth required, once the netcode has been trimmed as much as possible; splitting the load. This either means running 2 servers, and "clustering" them, or doing some rather technical and complicated Peer to Peer distribution.

Now the 1st option is a good idea, as the servers could split the load equally, and over all only a little extra is added to keep the servers sync'ed. The second option is bad; client's taking over some control is a bad idea, as at any level someone could alter the data and "cheat". So the peers would have to still talk to a master, or rely on some heavy checking - which would be likely slow down the experience - and rarely be cheat proof as there are so many places it would be possible to insert expoits..I rather like the idea of clustering servers though - ala MMORPG's.

Edit:
I think you'll find that "thin modes" on those games poll those vehicles around you more often, and those across the other side of the track, out of your view less often - again like a MMORPG you'd only get updates of those within your "viewing distance", and any critical packets from those outside - i.e. this would make it choppy if you wanted to see the vehicles on the other side of the "world", but seem very smooth to those close to you...

Does that make sense - or did I ramble a tad?

[Shotglass]

[totally off topic post]
AAAAAAAAAAAH not one person who knows what bandwidth means
[/totally off topic post]

[NotAnIllusion]

This is something i have been thinking about for awhile now but never mentioned. I just saw the NKPro will have this feature and im not sure if LFS does.



I have always thought that if someone is at the back of aston and im on the start finish straight then why would i want to receive their packets as often as someone who is next to me. I havent seen this mentioned anywhere as being implemented in LFS so i thought i would bring it up.
Maybe the "multiplayer speedup option" could have such a feature so it can be turned on/off too? Option because polling less frequently will have an effect on the data recorded which in turn will affect replays (I think:Looking_a )

[the_angry_angel]

[totally off topic post]
AAAAAAAAAAAH not one person who knows what bandwidth means
[/totally off topic post]The talk is almost correct, in terms of computer bandwidth; its the difference between the lowest and highest frequency of a signal or device. i.e. between 0KB/s upload and the line's theoretical maximum upload speed. The amount of data transfered (which we're talking about) is usually between this, and refered to as bandwidth required, rather than the technically true answer of data transfer required :razz:

[X-Ter]

[totally off topic post]
AAAAAAAAAAAH not one person who knows what bandwidth means
[/totally off topic post]
Feel free to explain at any time possible :)
I do like this when I calculate how many cars I can have in the race.
I test my bandwidth using one of the many serives on the internet (PCPitstop, TPTest etc.) and I get a number. This number I enter into LFS and then add cars until it says "No more or your computer will blow up and your wife will divorce you".

What I get is usually not the bandwidth I pay for (1Mbit upstream) but rather like 850Kbit, witch at the moment would allow me to host 17 cars and 23 guests. Right?... Right!... :)

If I switch to Nascar Heat, I can host 29 cars with that upload speed in thin mode. In normal or "thick" mode I end up with a limit of 16 cars.

[Shotglass]

The talk is almost correct, in terms of computer bandwidth; its the difference between the lowest and highest frequency of a signal or device. i.e. between 0KB/s upload and the line's theoretical maximum upload speed. The amount of data transfered (which we're talking about) is usually between this, and refered to as bandwidth required, rather than the technically true answer of data transfer required :razz:

no no no no ... what all of you are talking about is the symbol-rate the throughput or the transmission-speed
bandwidth is an interval on the fequency axis so its always in Hz

its a common mistake by computer scientists (just like calling a binary symbol bit) ... and one of my profs threatend to personally kick us back into first semester if we ever dared to confuse the two

[KiDCoDEa]

This is something i have been thinking about for awhile now but never mentioned. I just saw the NKPro will have this feature and im not sure if LFS does.

lfs does vbr mp for a few years now...
also a lotta other things other games dont even think about...

[sil3ntwar]

sorry vbr? variable bit rate?

[Krane]

lfs does vbr mp for a few years now...
also a lotta other things other games dont even think about...
Besides that, it's possible to limit bandwith usage of a LFS server by changing the packets per second setting.