Arma 2 bandwidth requirements

[galzohar]

I remember a long time ago I was spending a lot of time searching for this data, but couldn't find it anywhere (at least not in a precise form, more like "yeah 100MBIT worked for our X players session). However now when I have more experience playing on low-end connections with low player counts, I think I have this more or less figured out.

Keep in mind that everything here comes from seeing how many players can play smoothly vs how many players need to log in in order to clear see desync issues - Never actually looking at ingoing/outgoing data (can't do it anyway on a hosted server as far as I know).

One thing I noticed is that the amount of AI doesn't seem to have a noticeable effect on how many players I can get on the server without problems.

My conclusion so far is that you need something around 0.1MBIT per player. How?

All upload speeds were measured by speedtest.net

My connection: 0.2~0.23 MBIT upload. Maxmium players other than myself: 2, with perfectly smooth play. If 3 players log in, significant lag occurs and it becomes almost unplayable.

A friend's connection: Not sure whether it was 0.4 or 0.5 MBIT upload, but max players that could connect and play smoothly was 4 (other than the host), 5th player connecting would cause obvious lag.

Another one who I think (but not totally sure) had 0.8MB could have up to 7-8 players connect (again don't exactly remember, this was very long time ago, and I usually don't have that many players connecting).


If anyone has more data that could give us more accurate estimations of Arma 2's exact bandwidth requirements, please post it and I will try add it to the first post if it provides new information that everyone should have easy access to. It would especially be interesting to see if with more players we would see a non-linear increase in bandwidth requirements, as can be suspected when you look at the results I got.

[Günter Severloh]

Hello,
Only thing I can think of is the basic.cfg, not sure if that tells you anything, but its the codes that are
for performance tuning for a dedicated server seen here:
http://community.bistudio.com/wiki/basic.cfg

[galzohar]

Nah, this page (and other similar ones, such as Kelly's Heroes great dedicated server settings guide) don't really mention the exact (or even estimated) amount of bandwidth a server requires in order to run with X players. That's why I made this thread, so that we can have all info of this sort in 1 place.

[Mosh]

Good idea Galzohar, this question has been asked so many times with no real definitive answer. Many people wonder how much traffic their home networks can really handle.

From my tests on my own dedicated servers your results seem just about right.

I'd also be interested to see what others say.

[VisceralSyn]

The bandwidth requirement varies, depending on what mission you are running. Heavily scripted missions, with alot of AI, will have a higher bandwidth requirement, on average.

I was doing some testing last night, with my dedicated server in LAN. Setting the Min/MaxBandwidth's to 92Mbps/100Mbps. Connecting with my client, the server reported sending 128kbps to 12Mbps, depending on MaxSizeGuaranteed/MaxSizeNonGuaranteed. Which, left default 512/256 gave me the 128kbps, and when modified to 1500/1500 (MAX MTU ) the up skyrocketed to 12Mbps. I used MaxMsgSend setting of 16384 for all testing.

Also note, typically the server was recieving 1Kbps to 64kbps from my client. Test mission was Benny's Warfare 2.066 Lite CO.

Ideally, if you can get clients to use 128Kbps only-, you should be able to get 10 clients on a 1Mbps pipe. There are no 'defined' options on how to force clients to recieve a set amount.

...Syn...

[NoBrainer]

Due to the differences in clients and missions, we use 256k as a standard and I use 512k as limiting factor for telling how many clients that can connect.
But this is just to say that we can "only" have 50 clients on our 26mbit line.
But if you find the "exact" answer to this one, please do tell us.

256k is from OFP times and "confirmed" for ArmA. We still uses this for our Arma2.

[Freeborne]

Some rough estimates could be very useful for server admins, gathered from trial and error of other server admins.

Bare in mind that all figures would be rough estimates, and could vary greatly based on the mission being played.

You would also have different values based on average gameplay, joining in progress, and map downloading.

During normal gameplay, bandwidth usage is low, however the bandwidth required per client would spike when downloading a mission (start of game) or joining in progress (downloading mission AND all the JIP data to be up to sync with other players).

Then on top of that, there is factors you cannot estimate, such as players having custom sounds, custom faces, squad logos, etc.

[galzohar]

Yeah I completely neglected temporary stuff that only happen upon player connection or new mission loading, such as sending mission files, JIP info or custom faces, but those do happen only once.

If you look at the limits I've been getting, limiting to only 50 clients on a 26MBIT line seems very restrictive. Of course we don't really know if there are non-linear stuff with more players. Maybe try to push this higher and see what happens?

Regarding mission-specific stuff, while I did notice differences in in/out data reported by a dedicated server when you do different things in a mission or play different missions, as long as you don't do something crazy like run a quick loop with a publicVariable command, the actual requirement for smooth play doesn't seem to change too much - At least not enough to notice when playing with small player count and low bandwidth - Whether the mission was a TDM or a high-AI-count COOP mission, the maximum number of players that could fit on the same connection without lagging didn't seem to really change.

[Eclipse4349]

Just to add some experiences, I was hosting a single-town Warfare co-op mission I am working on last night. There was only one other player connected. The Blufor have 5 playable units synced to the Warfare module, and the Opfor had 5 unplayable units synced. The max squad size was set to 12.

The lag was so bad that units were warping all over the place for the connected player. I, of course had no lag, since I was hosting the mission. I have, I believe, a 2.0Mb upload, which I can verify with speedtest when I get back to it. There is no reason for only 2 players to lag a server. This leads me to believe that AI count definitely effects the scenario. Especially when those AI can add more units to their squads. My machine is a quad core Phenom II at 3.0ghz, with 8GB dual channel memory at 1066mhz. CPU usage was 40-50% max on any core at any given time, and memory was only 35% utilized. So the issue is definitely not hardware capability.

Assuming AI bots effect the amount of data that must be sent, I am going to treat each bot as a player. I am first going to try a 1v1 human player setup, with maximum squad size set to 5, so that total unit count, human or otherwise, does not exceed 10. I will adjust from there to see how far I can go before lag rears its ugly head.

Hopefully this will give insight for more complex mission structures like Warfare.

All my buds now have OA as well, so perhaps OA's improvements will help the situation. Thanks BIS for yet another great patch!!!!!!!!!

[galzohar]

I highly doubt a bot takes as much as a player, since I noticed no difference between TDM and "normal" coop missions (aka not warfare with a billion AI). I wouldn't be surprised if AI units require bandwidth, but I highly doubt it's anywhere near the requirement of a player. Especially considering that servers don't update AI positions very often for AI units that are far away from the player (hence all the complaints about "AI warping").

Another thing, if you want to check if your server is hardware-limited, especially in AI-heavy situations, you shouldn't really look at CPU/RAM/whatever%, but rather look at if your FPS are dropping or not (though this is something you probably would have noticed if that was really your problem in this case). When you run incredible amounts of AI, total CPU usage % actually goes down, because AI only run on 1 thread, and if that thread takes too long to complete 1 cycle, the rest of the threads running "wait" for it to finish and thus actually don't run as much, but of course your FPS goes down accordingly. It's as if the AI runs on a single core and that core is the bottleneck, however windows usually just moves that thread between cores to spread the heat around which makes it seem like your CPU isn't working hard at all when you look at the task manager, while in fact it is limited by its single-core speed (this is very easy to test if you just write a c program that runs a single infinite loop - It'll use 25% of each core even though it is running as fast as your CPU is allowing it to).

Do you have any idea of how many AI were actually running? I would have thought with 2MBIT upload you should be able to run so many AI that your CPU will die before you would notice any network issues with 1 player. Are you sure his internet was functioning right? Did you try a blank mission or mission with few AI in order to compare?