Well, it's tricky (Destiny)

by Kahzgul, Friday, April 15, 2016, 20:43 (3238 days ago) @ dogcow

In Destiny's case, my understanding is that they invented a new type of distributed "no-host" networking model where every console tells every other console where that console's player is and what that player is doing. When no data is received, the other consoles use predictive algorithms to continue animating the characters. This is why destiny looks so dang smooth, and also why your bullets don't hit where you were aiming all the time. It's... problematic, as far as I'm concerned.

Basically the player who lags his upstream connection *while moving* is predicted to continue moving in that direction by other consoles on the network. Then, when the upstream connection catches back up, the consoles say, oh, so you actually weren't there and the person appears to teleport. Keep in mind that they would still have taken damage from any attacks that were aimed at where they actually were during that time, because their downstream packets still resolve. It's the disconnect between displayed visuals and actual avatar position that causes the painful lag-related gameplay. And because of the distributed token-ring-esque network setup, a single laggy player can cause everyone in the game to periodically lose sync, even when they all have otherwise good connections, and it's not consistent because of how the buck is passed - sometimes only laggy mcghee is lagging, and sometimes (far less often) it's everyone, and that changes in the middle of matches.

In contrast, a player with an overall laggy connection behaves differently. They see everyone blinking around the map, and they themselves will blink around, too. In this case, where both upstream and downstream data packets are lagging, it will appear to the poor connection player that everyone else is lag switching, and has damage avatars separate from their visible avatars. To the non lagging players, the lagged guy will teleport a bit, but also move in fits and starts, taking no damage for a while, running into walls, firing every round in their mag at the same time, and then suddenly falling over dead. It's similar looking to lag switching from the outside but lacks the smooth damage dealing and evasive ability. It's also far more consistent.

On the lag switcher's screen, everything is smooth all the time.

On the lagger's screen, they are constantly blinking around the map, unable to shoot, and dying for no reason.

Traditional PvP FPS games have a host player (usually the guy with the fastest and most reliable connection) and that player's console is the referee for where everyone is. All packets move through his console, so if someone lags, his console makes them stand still *and continue to take damage normally* until they catch back up, and this applies to lag switchers as well. There are certainly still ways to cheat in those games, but lagging isn't one of them.