Hows Internet Gaming work so quick

[snedie]

Yeah i see what you mean, and i am guessing my soldiers netcode is all thats needed to be sent, not all the details on the map example that theres a rock or building by me.

Cheers

Correct, all that is sent is the information regarding your soldiers stats.

 

[Trifid]

But not the full speed of light. The speed of light in a vacuum is different to that of it travelling through a medium (think of light travelling through a prism which slows the light down and showing the different colours). I can't remember off the top of my head how much slower but a quick wiki says it's 35% slower.

To follow up, I dusted off my book on this and did a quick google and it agrees with this wiki page:http://en.wikipedia.org/wiki/Wave_propagation_speed

but i suspect a large amount of the delay is the routers processing where each packet of information need to go along its journey

Round trip delay (propagation, so ignoring everything else) is around 0.0532seconds (53ms) to New York from London.

If we take a look at other factors that add delay:

We have serialisation (the time it takes for a packet to be put on a link and it depends on the speed of the link, the size of the packet and is additional for every hop the packet has to transverse. IP header is 20 bytes, add on a the ICMP header, 8 bytes and then the ICMP payload (windows default is 32) we get 60 bytes divded by the link speed (lets say 1Gbps for each hop) and we get 0.00048ms for each hop (minimal).

Queuing delay can be quite high and is variable depending on network congestion and QoS policies. This is where most of the extra delay will be from.

Forwarding Delay (what I believe you are referring to as router processing delay is the time it takes from when the packet leaves the input queue and enters the output queue. These values are rarely quoted but are micro seconds in time (0.0001ms).

 

[TNGL]

The data travels just as fast, there is just more to send.

http://gafferongames.com/networking-for-game-programmers/udp-vs-tcp/

Have a read.

 

[WingZero30]

Travels at the speed of sound innit.

Isn't it more like that digital data is travelling at speed of light

 

[clubb699]

To follow up, I dusted off my book on this and did a quick google and it agrees with this wiki page:http://en.wikipedia.org/wiki/Wave_propagation_speed



Round trip delay (propagation, so ignoring everything else) is around 0.0532seconds (53ms) to New York from London.

If we take a look at other factors that add delay:

We have serialisation (the time it takes for a packet to be put on a link and it depends on the speed of the link, the size of the packet and is additional for every hop the packet has to transverse. IP header is 20 bytes, add on a the ICMP header, 8 bytes and then the ICMP payload (windows default is 32) we get 60 bytes divded by the link speed (lets say 1Gbps for each hop) and we get 0.00048ms for each hop (minimal).

Queuing delay can be quite high and is variable depending on network congestion and QoS policies. This is where most of the extra delay will be from.

Forwarding Delay (what I believe you are referring to as router processing delay is the time it takes from when the packet leaves the input queue and enters the output queue. These values are rarely quoted but are micro seconds in time (0.0001ms).

Well thanks for your time i am finding this very interesting in a twisted way


I must say i have really enjoyed this topic

 

[Trifid]

The fact that UDP (User datagram protocol, often referred to as, unreliable datagram protocol) is typically used rather than TCP is also a contributing factor. With TCP you need a 3 way handshake, when using UDP, it just sends the packets and couldn't care less whether you receive them or not (hence their being no need for a 3 way handshake). Obviously, the 3 way handshake adds to the amount of time it takes for data to travel between two destinations.

I always hate that UDP is considered unreliable. It has its uses just as TCP and you should use the one that is best suited to the situation. There is no point using TCP for a phone conversation as I couldn't care less if I receive a resent packet that was dropped 5 seconds ago. It is pointless and the receiver phone would just discard it if it did receive it 5 seconds late. For a phone conversation UDP could be considered more reliable too as RED/WRED will drop TCP/IP packets to throttle back the window size (the amount of traffic it will send before waiting for confirmation that it has received it.) And then what would it do if the sender phone was told it had to send less data? If it was setup using TCP, it would just cause the conversation to become choppy at source, more so than if it just let network congestion drop the packets. But anyway this is more down to correctly implementing QoS.

 

[RomanNose]

I've never heard of a roundtrip time between the UK and US being less than around 65ms, and that is under fairly optimal conditions (between major exchanges in London and NYC). Home users will see upwards of 70ms and that is assuming they live close to London, have a very low latency connection themselves and are connecting to a server hosted near to the destination centre in NYC.

In fact the theoretical minimum roundtrip latency based on the distances between London and NYC is probably around 39ms, assuming you had a 100% efficient connection operating at the speed of light going in a straight line with no processing delays at any point (clearly this isn't feasible).

I always thought that ping was there and back. Woops. I never really knew that distance was that limiting on latency and I always thought it was the number of hops that caused it. Just shows that you can learn something new everyday.
The speed of light is so unimaginably high that I never expected it to have such an impact on communications.

 

[Trifid]

I always thought that ping was there and back. Woops.

When you ping from your computer it is round trip. Some games may halve this value though (so you get the latency to the server).

 

[mrk]

Easiest way to picture it is when Neo "sees" the Matrix code before his eyes, that's pretty much what it is.

01100100 01101111 00100000 01111001 01101111 01110101 00100000 01110011 01100101 01100101 00111111?

 

[arknor]

1's and 0's is outdated

 

[AGD]

Simply put, the game running on your computer extrapolates the movement and positions of everything from the current state and then periodically corrects everything when it gets the real data from the server. Because the times between receiving the real data are small, and the world is 3d and not very discrete you don't notice the corrections.

Some things which don't affect the game state (such as visual effects) don't need to be sent from the game server but can be done locally.

 

[arctine]

Hi all,

Well this is a kinda strange question but its doing my head in lol, but how on earth do they manage to make say battlefield 3 online work in real time so quick, i mean someone can be in UK and america along with 62 other players and we all see the same thing instant.

How do they manage to process all the details so quickly? do they only have to send certain data etc come on plz i need help with this one


Happy new year lads

Clubb699

How can light from the sun reach the earth so quickly despite being 93 million miles away?

Because light energy is quick.

Electrical energy is instant. It's not hard to imagine

 

[steve-h]

However for 64 players you need a decent amount of upload speed, where as most home connections only have good download speed.

no you don't lol... you still only send your data to the server.

 

[kayomani]

Simply put, the game running on your computer extrapolates the movement and positions of everything from the current state and then periodically corrects everything when it gets the real data from the server. Because the times between receiving the real data are small, and the world is 3d and not very discrete you don't notice the corrections.

Some things which don't affect the game state (such as visual effects) don't need to be sent from the game server but can be done locally.

Its all unnoticeable until you die around a corner ;D

 

[Trifid]

How can light from the sun reach the earth so quickly despite being 93 million miles away?

Because light energy is quick.

Electrical energy is instant. It's not hard to imagine

An electrical signal down a copper cable travels at roughly the same speed as light down a fibre cable.

 

[arctine]

An electrical signal down a copper cable travels at roughly the same speed as light down a fibre cable.

Electricity doesn't travel, electrons do. The emw is what travels at the speed of light.

Either way, what's your point?

EDIT:

Read your post wrong, ignore.

 

[agnes]

Some chap on the phone spectating...

 

[I_M_Weasel]

Even on VDSL it still goes over copper and therefore uses sound passed the cabinet. Its only fibre to the cabinet.

So its moving at the speed of sound then? Are you sure?

 

[Dave M]

So its moving at the speed of sound then? Are you sure?

It is wrong but not as wrong as you might imagine.

http://en.wikipedia.org/wiki/Velocity_of_propagation

Electrons move quite slowly, slow enough that you'd notice the delay between turning your light switch and the bulb lighting. But as the wire is already full of electrons you push one out the other side as soon as you push one in this side - except you do still have to wait for that compression wave to travel down the wire.

Just as with the speed of light it will depend on the conductor but in any reasonable example it will be much much faster than the speed of sound.

 

[Zefan]

Even if he isn't on dial up but instead on DSL then it still works on sound once it get's to the copper which in most cases is from the exchange. Even on VDSL it still goes over copper and therefore uses sound passed the cabinet. Its only fibre to the cabinet.

No. Analogue electrical signals are not the same as vibrations through air.