Slow download speed [solved]

[sofasurfer]

This isn't a linux specific topic since I had the same problem with winblows. Its just that NOW I care enough to ask.

I connect at 31 k/s usually. I have a 56k/s modem and have rarely connected at 56k/s.

 

1) When I'm downloading network monitoring shows that I am receiving an average of 4-6k/s.

Where is the 31k/s that my modem is connected at?

 

2) The download shows that it is coming in at no more than 4.2k/s.

Why is this less than what the network monitor shows?

 

3) When a download first starts, or when it drops to 0k/s and than increases again, it can shoot up to 10 or 15k/s, but after 5 or 10 seconds it goes back to 4k/s or so.

Since the download can start at 10 or 15k/s why can't it stay that high?

 

Am I having a malfunction or is this the way things are?

[Gowator]

Firstly Network bandwidth is measured in kilobits per sec Kb/s whereas data is measured in kilobytes per sec KB/s

This may account for some confusion...

 

Secondly 56k is just a nominal (or maximal) figure because the modem actually works at 33,6kb/s and the rest is achieved via hardware compression with the ISP, hence the files you download are compressed by different amounts and some like .zip or .bz etc. are already compressed and can't compress much further, indeed the max compression algorhythm in some of them is better than the 56k algorithm so they are actually bigger after compression.

 

Thirdly the competition nowadays for efficient 56k ISP's is pretty small since you can multiply your bandwidth so many times over just using DSL ISP's are not competing to be the most efficient at providing 56k services.

 

Fourthly most of the internet is not tuned for analogue speeds anymore, routers are set to send/receive higher packet sizes ... imagine a set of packet bursts but the size of the packet is more than you can download so it ends up waiting on a server and faster connections get priority.

5 yrs ago I had a 1/2 Mbit line which was frequently waiting on the ISP or on the routing, now I have a 22Mbit line which is rarely wating on routing but still has to wait on individual sites. The secondary back bone is running on T1 and T3 (which are ATM protcols not ethernet) and these themselves have packet tuning so they try and balance the overall load and if 50%+ of people are using 1/2 Mbit up then these loads adversely affect the smaller loads for dial up. That is if 1000 people are all using 1Mbit and 1000 using 56k then (call it 1/20th Mbit) then there is 20x the traffic using larger packets so the routers are biassed towards this traffic as opposed to individual users..

This is a hard concept to grasp in a way because the ISP just moves packets .. the engineer doing the tuning probably just wants to move as many packets as possible using the least equipment so it is strongly biassed in terms of high bandwidth users.

 

An analogy is tuning a disk, if you have lots of small files you use a smaller block size so as to waste less space and use agressive caching but of small files and high numbers... if you use a lot of large files you have a larger blocksize and the cache aims to swallow single larger files ...

 

The routers are much the same, because under most circumstances the ISP will try and use the least bandwidth possible ... (it costs money) so they try and squeeze the max out of it.

[scarecrow]

You are still confusing metrics, I'm afraid.

Your modem nominal speed is 56k (kilobits), which means that the maximum nominal download speed you should expect is 56/8 = 7K (kilobytes).

If you connect at 32k on a 56k line, the only thing you can do, independent of operating system, is asking your phone company for a phone signal quality check.

Edited April 30, 2006 by scarecrow

[sofasurfer]

Thank you.