How to implement lockstep model for RTS game?

Question

In my effort to learn programming I'm trying to make a small RTS style game. I've googled and read a lot of articles and gamedev q&a's on the topic of lockstep synchronization in multiplayer RTS games, but am still having trouble wrapping my head around how to implement it in my own game.

I currently have a simple server/client system. For example if player1 selects a unit and gives the command to move it, the client sends the command [move, unit, coordinates] to the server, the server runs the pathfinding function and sends [move, unit, path] to all clients which then moves the unit and run animations. So far so good, but not synchronized for clients with latency or lower/higher FPS. How can I turn this into a true lockstep system?

Is the right methodology supposed to be something like the following, using the example from above:

Turn 1 start

1. gather command inputs from player1
2. send to the server turn number and commands
3. end turn, increment turn number

The server receives the commands, runs pathfinding and sends the paths to all clients.

Next turn

1. receive paths from server, as well as confirmation that all clients completed previous turn, otherwise pause and wait for that confirmation
2. move units
3. gather new inputs
4. end turn

Is that the gist of it? Should perhaps pathfinding and other game logic be done client side instead of on the server, if so why? Is there anything else I'm missing? I hope someone can break down the concept, so I understand it better.

Answer 1

https://gamedev.stackexchange.com/search?q=client+prediction

You'll want to do client side prediction to deal with latency issues.

In essence, do everything exactly as you have set up, but when the client sends the command to the server, the client assumes the command is valid and performs the pathing algorithms and begins moving. The server can then validate and send the command to all clients to simulate while the server performs the actual pathing.

The only time you want to send unit data is when the units are taking a new action. IE: When a unit starts moving up after it has been moving left. The clients assume the unit will continue to move up until they are told otherwise. The same follows for attacking and performing actions.

This style is used a lot in MMO style games like World of Warcraft.

another link: http://gafferongames.com/networking-for-game-programmers/what-every-programmer-needs-to-know-about-game-networking/

Answer 2

Here is how I understand it:

In a lock step networking model, the entire game simulation is ran on each client. This includes path finding.

You should be sending each player's inputs to each client. Each client will then need to be able to process the inputs and run the simulation locally.

The benefit here is it significantly reduces the amount of information sent over the wire. In an RTS you can have thousands of units. In the client/server model you have you would have to send the path information for each unit every game frame.