Difference between bandwidth and actual speed ?

Question

I leased a line from an ISP that offers me a bandwidth of 4mb/s.But I receive only a speed of 160 kbps when downloading files over internet.I found that the actual speed I receive is the ISP throughput.

Why should i pay for unused bandwidth if i can only get a speed that is in kbps range ? Also, what is the significance of ISP advertising in terms of bandwidth rather than throughput ? what are the factors that determine ISP throughput ?

I find most of the people confusing Bandwidth with the actual speed they receive.People think that they get 4mb/s speed while accessing a file over internet when they have a leased line of 4 mb/s bandwidth.

Solution 1

Your ISP is providing you with a 4 Megabit per second throughput. There are 8 bits in a byte, so your actual download speed should be about 0.5 Megabytes per second (or 512 kbps).

However, there are many factors that can slow down internet traffic, normally always from latency in hardware.

If your download speed is 160 KB/s, you should first see if other devices on your local network are experiencing the same problem. If not, look into the hardware (network card) or software on your device to see if there is something going on there that is slowing down the network speed.

If all the devices on your network are at 160 kb/s, check out your LAN setup. If you have multiple routers or are using a WiFi, investigate upgrading or troubleshooting those bottlenecks. A good way to test this is to directly connect your computer to your ISP's modem. If your speed is faster, then your local LAN hardware is bottle-necking your speed.

If you still have slow speed even with your computer connected directly, it's time to call your ISP and crush some skulls.

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Difference between bandwidth and actual speed?

Imagine that your connection to the internet is like a river. Bandwidth is the width of the river. If you have a tiny creek of a river, then not much water goes through at one time. If you have a massive, mile-wide river, more water can flow through it at once.

Speed is closely related to bandwidth. The wider (bandwidth) your river is, the more data you can access at once, and, obviously, faster.

If I put a bunch of water-sucking machines along the river, it still is just as wide, but each machine will suck less water down the line, because they are "eating all the bandwidth". The water is divided among the clients, and each client will take longer.

Translate that analogy to your network - there is something along the "river" that is narrowing it - your ISP maybe, but probably a router. There could also be devices on your network that are sucking data and slowing you down.

Solution 2

The bandwith is the maximum possible throughput.

Thus, if your ISP gives you a 4 MB/s bandwith, your actual download speed my be slower than that. That happens if the remote server cannot send the data fast enough, the network of your ISP is congested or your pc cannot receive the data fast enough. While the latter is usually no concern, the former can be significant.

Given a good sample of fast servers and tests at differnt times of the day, one can reasonably expect to get the 4 MB/s. If not, you are getting ripped off.

If you have a good ISP, congestion is also not a problem. The download speed then depends on the download source and your bandwidth.

Comments

[Ramhound]

Seems like you might have it confused also. Bandwidth is the amount of data throughput your ISP will allow. Your actual speed will be dependent on several factors including the server's bandwidth and your own hardware's supported network throughput.

[Jesse]

Are you sure it's 4 megabytes per second or 4 megabits per second. 4 megabits per second should get you up to 512 kilobytes per second. With this said 160 kilobytes is still clearly under your rated speed.

[Synetech]

But I receive only a speed of 160 kbps when downloading files over internet Sometimes I get much less, sometimes I get much more. You need to run a proper speed test to find out what your actual maximum speed is, not just a few random files because those may have been from slow servers or during times of heavy load.

[Thanos]

If someone cannot use the maximum bandwidth the ISP provides, does it mean that either the ISP is messing around or there's a hardware issue? I mean, the server that the data are coming from might not be able to stream the data fast enough, isn't that right?

[Admin]

@Thanos That's true. However, your ISP is legally obligated to fix such issues if you report it to them. Most ISPs are also willing to let you know they are experiencing such issues if you call them. I deal with problems like yours all the time, but almost 99% of the time, it's something to do with the LAN or a client on the LAN.

[Thanos]

When it comes to P2P sharing, for instance... If my line supports 24mbps down but yours 1mbps, my downloaded speed will be restricted to 1 mbps because of your connection. I've never thought of a hardware or lan issue. It's good to know!

[Admin]

@Thanos Correct. The slowest piece of hardware that passes data to your computer will bottle the speed down to that limitation (including your network card). If I have a 10 billion mbps router, but my ISP only supplies me with a 25 mbps connection, then 25 mbps I shall receive.

[Admin]

@Thanos However, connections on your LAN (between two computers locally, for instance) will be much faster, as their only bottleneck is the network hardware and themselves.

[Thanos]

I can't argue about local connections! My point was just on the internet ones!

[Ashildr]

@Moses i have a doubt over the river analogy , whether i get a river of my own or do i share a river with rest of the consumers ?