what is maximum throughput and bandwidth??

[chang542]

It may be a dumb simple question, but I am confusing myself the more i think about it, and i'm not quite sure what people here are telling me is true...

So when I say I have a 12meg pipe out of here to our WAN, at what point do I max out my bandwidth?

I would think if you have a transmit and receive link in a full duplex environment, you can send and receive 12meg on each at the same time.

But others say its an aggregate of both, so if I'm sending out 6meg, I can only receive up to 6meg at that time... or if 9meg out then only 3meg in, and so on....

So how does it work?

 

[LawnBoy]

It's not a dumb question, and the answer is not all that simple...

Let's take for example the adsl line I have at home. I can download up to 1.5 Megabits per second and can upload up to 512 Kilobits/sec, for a combined aggregate of 2 Mb/sec. When you say you have a 12 Mb pipe, I don't know whether you mean 12 Mb upload or 6 Mb up and 6 Mb down. Check with your provider for what your connection rates are.
Usually these rates are fixed, meaning that if you're not using all of your upload bandwidth, you don't get more download bandwidth.

In my experience, full-duplex is rarely full. In fact, I don't think I have ever seen both directions full at the same time.

Throughput is more of a real-world measurement of how much data can be transferred. Many, many things will affect throughput, not just the speed/capacity of your line. If the server/switch/router/proxy you are using is busy, the throughput will be lower. If a packet has to be resent, if your network has heavy ARP traffic, if VoIP has priority, if NetBios is running, all these things can lower your throughput.

hth.

 

[jimbopalmer]

Most WAN links suffer from high latency, that is it take a long time to get a reply compared to the time it take to send a packet. If you use a protocol that sends one packet, waits for a reply, then sends the next packet. you can consume a lot of time just waiting for replies.

As such, most file transfer protocols use a window approach, send as many packets as the other computers receive buffer window can hold and THEN wait for at least one reply to come back. You can speed these up by choosing responsibily larger receive buffer window sizes.

http://www.dslreports.com/tweaks

is one site that can help you tune your throughput.

I tried to remain child-like, all I acheived was childish.