How does load balancing routers work?

[kaanimo]

So, I'm not much experienced with networking so I didn't quite understand what I found on Google searches. I know that you need more than one internet connection (thus more than one modem) and you connect them to the router. Then I also understand that you can use one connection mainly and have the other connection as a fail-over.

But my the thing that confuses me is can you use two connections with the same client to achieve more up and down speeds. For an example, I have two 100/10 Mbps connections and I plug them into a load balancing router and boom I have 200/20 Mbps on one client. Or is it just one 100/10 connection to one or more clients (for an example one computer) and one 100/10 connection to other clients?

[Electronics Wizardy]

Depends on how its setup, but normally is spreads the isps between sessions, so one session gets one isp and another session gets another isp. You can't send a single session at a high speed this way. 

 

 

[BrinkGG]

Just now, kaanimo said:

So, I'm much experienced with networking so I didn't quite understand what I found on Google searches. I know that you need more than one internet connection (thus more than one modem) and you connect them to the router. Then I also understand that you can use one connection mainly and have the other connection as a fail-over.

But my the thing that confuses me is can you use two connections with the same client to achieve more up and down speeds. For an example, I have two 100/10 Mbps connections and I plug them into a load balancing router and boom I have 200/20 Mbps on one client. Or is it just one 100/10 connection to one or more clients (for an example one computer) and one 100/10 connection to other clients?

So for your example, here are the options you would have for conventional load balancing: 

Failover LB: One connection is used all the time, and only when that first connection can't handle the entire network's bandwidth is the second connection used. 

Weighted Split LB (50/50, 60/40 or similar): The first connection used until it hits a preset load limit, then it will start using the second connection till both are at limits, then both will increase above that to meet the load need. 

unweighted Split: Both connections are used as close to equally as possible. 

     All of the above can only use the maximum of ONE connection per client. (2x 100/10 connections, one client can only hit 100/10 at max unless it's split workloads like torrenting) 

 

Pure split (Rare): "Bonded" connections that allow for full usage of multiple connections, splitting packets evenly and reassembling them before reaching their destination. 

This is talked about in this LTT video: 

 

 

Hope this helps! If you have any other questions, feel free to ask. 

[mtz_federico]

You could also (but it is more complicated and not for home networks) use bgp to find the best path to an ip. But I don't think that using bgp is considered as "load balancing"

[Falcon1986]

Another thing to take into consideration when doing something like this is that you should have at least 2 different ISP sources. It makes no sense to have 2 connections from the same ISP as if they have a failure at their end, both connections are likely to fail which defeats the purpose of failover.