Multiplayer games and the internet

[zombieSquirrel]

Keep in mind I'm fairly new to how computer and internet stuff works . Here's a simple question in the form of a scenario.

 

Let's say you are playing StarCraft with a friend, who is hosting the game with his/her computer. Now let's say there's a two second delay between your computers. If you order a group of marines to move, how long does it take for you to see them start moving on your screen?

[Mr Skeptic]

Some games compensate for lag by allowing the lagger to function as if there were no lag. Then there are inconsistencies, but they can be resolved fairly well if dodging is hard. In other games, the lagger gets penalized, often attacking things that aren't there.

 

Generally the screen shows what you would see if there were no lag, even if it is not accurate.

[insane_alien]

a two-second lag would be extremely severe. typically lag is measured in 1000ths of a second(milliseconds) and can be quite noticeable if it is above 100ms

[khaled]

i can't tell you in numbers,

 

it depends on many things:

 

1. your internet connection bandwidth

2. the host connection bandwidth

3. sometime the mechanism of the game

[insane_alien]

high bandwidth does not mean low latency.

 

a truck full of harddrives barreling down the motorway hasa high bandwidth, but also an extremely high latency.

[khaled]

bandwidth to data in a Network Link

 

is just equivalent to,

 

speed to object in Space

[Mr Skeptic]

bandwidth to data in a Network Link

 

is just equivalent to,

 

speed to object in Space

 

If you're going to make an analogy, at least make it a good one. Perhaps momentum instead of speed? If you have less stuff moving faster you might still get the same amount. Anyhow, bandwidth has little to do with the question of latency.

[insane_alien]

right, seems i need to explain this a little more.

 

lets say you want to transport some data from A to B. Bis 10 km from A

 

you have 2 options, you can send it down a 1Mbit/s connection or send a harddrive by car at 60kph.

 

for clarities sake we will assum a 100GB harddrive.

 

so, the bandwidth for the connection is 1Mbit/s but what's the bandwidth for the harddrive in the car.

 

well it'll take 10 minutes to get from A to B assuming a constant 60km/h so thats 1.333Gbit/s

 

so the hardrive has more bandwidth(more than 1000 times the bandwidth)

 

so according to you the truck should have a lower latency.

 

unfortunately not. the truck will have a latency of 20minutes(there and back with the reply). always.

 

the latency for the wired connection will be quite low(however long it takes for a signal to be sent and then sent back which will be a few milliseconds at most.).

 

big difference.

[khaled]

what do you mean by "the truck",

 

you mean the Package that holds data for transfer ?

[Mr Skeptic]

He means a vehicle with lots of wheels and weighing a few tons. They're slower than electricity but can carry a lot.

[khaled]

He means a vehicle with lots of wheels and weighing a few tons. They're slower than electricity but can carry a lot.

 

i don't get it,

 

what have a truck with wheels to do with online gaming

 

.. and data transfer rate between Client & Server

[insane_alien]

because i was trying to explain why latency and bandwidth are two different things and that for online gaming it's latency that is the important one as there isn't usually a lot of data exchanged.

[Mr Skeptic]

i don't get it,

 

what have a truck with wheels to do with online gaming

 

.. and data transfer rate between Client & Server

 

Because if it's a truck full of hard drives, then it has a tremendous bandwidth. Unfortunately, the latency might be a problem...

[khaled]

now i get it ...

 

out of my study experience in computer science,

 

larger amounts of data = higher possible error %

[hobz]

They will probably start moving right away. They will most certainly not move on the host machine before the move order is received with a 2 sec delay.

 

The game could also wait for the host to confirm that your troops have received new orders, and not allow the move order to be executed before the host has confirmed. In this case, there would be a 4 sec delay. But by that time you would probably have quit the game and found something else to do.

[khaled]

i just imagined a truck with the following written on its side,

 

Flying Hard-disk company !

 

,lol

[Charlatan]

Keep in mind I'm fairly new to how computer and internet stuff works . Here's a simple question in the form of a scenario.

 

Let's say you are playing StarCraft with a friend, who is hosting the game with his/her computer. Now let's say there's a two second delay between your computers. If you order a group of marines to move, how long does it take for you to see them start moving on your screen?

 

Both computers slow down. It is called communication. There is a server and a networking point. The server cannt process information not on it, it does not guess, it relays stuff around. You both are like held up like.

[bascule]

Most games use UDP. UDP is a low latency protocol as compared to TCP, but carries with it the potential for dropped packets.

 

Dropped packets are okay though when you're trying to communicate the positions of various players or units within a virtual world. This is because units positions are constantly changing, so if some packets get dropped their movement will just get jerkier. Every new packet that comes in with a new position invalidates the previous packet, so it's okay if a few get dropped here and there.

 

A lag of 2 seconds is completely ridiculous. Even when I was playing games (at least UDP-based ones) over a dialup modem connection my lag averaged around 300ms. After initially moving to a cable modem, my ping averaged about 50ms. Nowadays it averages about 9ms.