First off, read the thread that's stickied titled "Explaining Lag Compensation and Networking". TheUser did a great job (link to it here http://callofduty-forums.com/community/threads/explaining-lag-compensation-and-networking.51648/), and will clear up some common issues right away. I will try my best to not reiterate his points too heavily, but rather focus on the manageable effects of lag. Also, we are not getting into the technical aspects, like time stamping or whatever (I am not a programmer, simply a guy that learned too much about CoD), merely the more applicable concepts. But on to the point, here!

I hear sooooo many people complaining about the lag on BO2. I am going to tell you, right here and now, it's your internet, if you are having problems consistently. Barring that, you are blaming something that you, yourself are taking advantage of. Please, for the love of all things holy, stop blaming lag compensation; you are incorrect, misinformed, and possibly just looking for something to blame when you are playing poorly.

I get it, everyone thinks they are a great player, and it's the game's fault, other people's connection quality causing issues (sometimes true, explained later), or something else responsible for their deaths, but rarely is this the case. Get over it. Stop raging and keep reading.

Let's start with a few terms that we need to discuss to give you a better idea of what we are dealing with and how to use it. We are concerned with latency, lag compensation, and client side hit detection.

I'll rehash this a bit. Latency (ping) is connection speed. This is the most important factor of how effective your connection speed is. Basically, it indicates your ability to send game data quickly, with faster speeds obviously being preferential.

Lag compensation IS NOT what everyone thinks it is. The idea is that it is some sort of great connection equalizer. This is not the case. Lag compensation is essentially predictive movement, allowing the game to run smoothly from a player's perspective, regardless of moderate differences in connection speeds. Read more from the "Explaining Lag Comp." thread regarding this, if you need to learn more. It plays a role in this, so it bears relevance.

Client side hit detection is an important concept, however, and one that is seldom brought up. To state this very simply, what you do on your screen is what is going to happen. Let us go into this further...

Essentially, when you fire at an enemy (and hit him enough to kill him, let's say) your game sends the data to the host saying, "Hey! I just shot and hit this guy! He should be dead!". You don't instantly get hit markers, nor does the target instantly die, as your game is waiting for the host to get your message and go, "You're right! You did hit him, and he should be dead! I'm updating the global game state to reflect that!". The host, which is updating all the client games, then sends back the game state, with your hits/kill included. NOW you see your hit markers and the kill. This typically happens very quickly (dependent on latency), so most of the time you don't notice much amiss, but is noticeable when the game is really laggy.

However, there are many situations where players are shooting each other; how does the game handle this? Say, for instance, player A is shooting at player B, and neither of them are host. Player A (on his screen) kills player B slightly before player B kills A (on his screen). Both players think they got the kill. The way this works is the host takes the first player to report the kill, and renders the inputs of the "dead" player (in this case, player B) void. The result of the encounter is that player A gets the kill, and player B dies, much to his dismay. Let me point out, however, that this is fair, as with equal connection speeds, he did get the kill first.

Now that that is out of the way, what does this actually mean to somebody playing BO2? Why do we care?


Because we can use lag compensation and hit detection to win battles! Yes, you can use it as a weapon, and many good players actually do. Let us detail this...

When you are playing the game, you are really seeing the game a variable amount of time in the past. If I had to ballpark, I'd say between 100ms (great connection) to 150ms (good connection). All of the other player's character models are actually reflecting where the player's views were that period of time ago. A guy in a straight line is actually (on his screen) a little bit ahead of where you see his character model. You don't observe this, as with lag compensation and client side hit detection, because you can shoot the character model that you see. Be thankful; many games didn't have this!

But, because of this, players can essentially be in front of their character models! On their screen, they already entered a room, even though their model (for everyone else) has yet to enter the room. This leads to what many players complain about; the players instantly charging through doors and killing people with impossible reflexes. Yeah, it's annoying, but stop being stupid, since you can (and already do) as well. Lets run through an example.

Player A is at a corner, currently hidden.
Player B is camping around the corner, looking at A's direction.

Player A starts moving around the corner into B's LOS. He sees B.
Player B doesn't see anything (A's character model is still behind the corner).

Player A starts lining up a shot on B.
Player B sees A's character model rounding the corner.

Player A fires, killing B on A's screen.
Player B aims at A's character model, which is now aiming, B might get off a shot or two.

(The host receives data from A that B is dead)

Player A gets the kill.
Player B dies, having the impression that A has an amazing reaction time.

This is just how the game works, whether you love it or hate it. BUT, remember that you can create situations where you will have an advantage do to this! Some tips.

1. Remember that your character model is behind you. This is what enemies are shooting at. Because of this, it is best to be the aggressor in some situations, because your model will be hidden, giving you a slight reaction time bonus. Generally, this only applies if you are currently behind cover; it's the leaving cover part that gives you the advantage. Campers get the short end of the stick on this one, as they will perpetually be disadvantaged when challenged by aggressors (from a networking standpoint).

2. Your lagging model hurts your odds when moving to cover! Since your model is behind your view point, you think you are safely behind cover when you (on their screens) are still moving to safety. That coupled with client side hit detection delay means you will die often when heading to safety. Remember this and don't expose yourself to situations where you would have to run to cover!

3. Don't always stand still when being defensive. Rather, it is better to pop into the area than head back, as opposed to just standing there. This way, you gain the aggressor bonus. Be aware, though, that your model will linger after you head back to cover, only do this in advantageous situations.

4. Lag can actually help, but it also hurts. From a model standpoint, the more you lag, the more your view point differs from your model. This can help you aggressively, but not defensively. You will have more of an advantage from cover, but will be more vulnerable from attack. Bear in mind, however, that the game will appear more choppy to a laggy player, and it would be hard to take advantage of this aggressive bonus, since your model (and game state updates) are so far behind.

Generally, this isn't that big of a deal, even though players make it out to be. Even if it was a big deal, it is fair.

Lag, which everyone complains about giving players an advantage, DOES NOT in actuality. This is not a valid argument.

Hosts do have an advantage. There just isn't a way around this without dedicated servers.

If I can think of something else relevant, I will add it here.

 

Haha I said I didn't remember his name offhand, not that I didn't remember how to spell it. Regardless, I attributed him.

Also, I didn't mean to rehash his stuff, as it needed to be briefly covered, but was forced to in order to explain the practical effects on gameplay/how to use it, something he didn't really touch. He did a great job explaining his stuff, though, and I welcome his criticism.

 

Slow, ponderous code isn't the same as broken. It's consistent, just terrible. I'm not arguing that point, just merely explaining how this works. Bad internet makes bad gameplay, period (that we all can accept, I hope).

EDIT: Watched the vid. I agree with what the guy is saying, and nothing he is saying really contradicts what was said in the OP. The code is slow, but fair. Besides, as the guy says, advantages/disadvantages.

 

It's not like Halo 2, when the host had a painful advantage, making the shotgun absolutely unstoppable, but you'll notice a difference. Primarily, you'll get hitmarkers immediately, as there isn't a two way delay on game state updates. I, personally, enjoy it when I pull host, but the difference isn't that dramatic.

Also, you have to remember that if an artificial delay is added (I don't know anything about this, I'll take TheUser's word on it), it's merely offsetting the latency of the other players, making the host more like a standard player instead of a superior host.