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Author Topic:   network pings
Rex R
Member
posted December 11, 2002 02:16 AM            
while testing a mod pak I had a chance to play with various server settings.
when I had the server rate set to 3k and fps to 10 my client was getting a ping of 100, at 10k 10 fps 100 ping, at 10k and 20fps ping dropped to 50, at 10k and 40fps the ping was 34. apparently fps has a bigger impact on reported ping than netrate

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BamZipPow
Member
posted December 11, 2002 05:37 AM            
That's pretty cool! I guess we could always bump it up for network games, eh?

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KiLlEr
Member
posted December 11, 2002 09:32 AM            
Of course it does

The server rate is the maximum amount of data to be sent out to each client in one "packet" (not to be confused with a network packet). On a stock server, you can crank this up and it would have no effect (or hardly any) as TM dosen't hit that limit.

THe FPS is the number of "packets" (not to be confused with a network packet) to send out to each client per second. Double it, and TM will send out 2x as many "packets". triple it, then it sends out 3x as many "packets".

The ping however is a bit of a lie. If you send out twice as many "packets", you're also sending out twice as many pings, so the ping rate the players would see will be half as much. Why? The ping rate that TM reports is the time between "packets", and not the actual trip time. If your connection can't handle the data, packets (actual network packets)will begin to be delayed and even dropped causeing worse lag and a fluctuating ping rate (which is why a 40 fps showed up as 34). As each client will get a max of 400kbytes worth of data per second, your connection may not be able to handle that. If 4 people are connected, your connection has to process a max of 1.6 megabytes per second. The calculation:

(Number of players * FPS * Net Rate) * 1.144 = max bytes/sec

The easiest thing to do is find out your upload rate and take 85.6% (leaving 14.4% for overhead). Then divide the result by the maximum number of players you want to allow. Then take this result and guesstimate a netrate and fps that (when multiplied together) is equal to or less than this value.

If you want to allow 56k users online, then your netrate must be between 10-14 otherwise the modems will cause severe lag. (A typical modem connection will give you 3500-4500 bytes per second)

Oh yeah, and make sure the netrate is a multiple of 536 (round down), as this is the maximum amount of data that an IP packet can hold and making your netrate a multiple of 536 makes for the most effecient use of IP packets. As a side note, each IP packet sent out adds an additional 40 bytes of header and IP information (the 14.4% overhead).

[This message has been edited by KiLlEr (edited December 11, 2002).]

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CyberCannon
Member
posted December 11, 2002 01:23 PM            
Kiler, you lost me, but since I only have dial-up I don't think I will be hosting a server anytime soon. If I ever get broadband, I may be hollering at you for help.

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Rex R
Member
posted December 12, 2002 04:41 AM            
well I happened to notice that, when I joined a game in progress the reported ping was 34 and when joined a dedicated server it was 50 so I got curious. note it prolly wouldn't make any difference to try and crank it up any higher than 40 fps anyway since that appears to be what tm tops out at in single player (to judge from my 'tank.log')

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