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Correcting a Protocol (MTU) fault is essential

First select the correct the Port Speed,
the optimum modem Maximum Speed,
and the best DUN settings.

Update the modem driver.

Then optimize the MTU setting.

Always be wary of harmful line noise

These Pages will show you what you should (must) do to dramatically improve your average download rates.


Introduction to Modem & Internet Speedup Tweaks

The following Pages will show how to substantially enhance home Internet performance. But what download times should you expect to achieve?

Download times normally vary considerably. Many factors, such as your modem, quality of connection, ISP load, server responsiveness, and Internet routing impact, on download times.

Also involved is the form of compression you normally use for your own particular types of downloads; ordinary files, pre-compressed files, or the mixed variety (Web pages).

Comparisons: Always compare like with like - it is always better to make comparisons at the same time of day at off-peak hours, and with the same location (initially your own ISP, and then further afield). Fortunately you will also notice considerable improvement at peak times, but peak times are too variable to permit reasonable comparisons.

If you test your download speeds, at off-peak hours, before and after making the suggested changes, you will have real-life figures that demonstrate the marked improvement (read Test1).

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You must know the difference between Kbps and KB/sec

Kbps stands for kilobits per second (kilo = thousand), and refers to the speed at which your modem sends and receives information. Example: 33.6 Kbps = 33600 bps (where bps means bits per second). A 36.6K modem is one that can, at best, transfer data at 36.6Kbps (36,600Kbps).

However your download speeds are usually expressed K/s or KB/s which are KiloBytes per second. As the Kilo now refers to Bytes, 1 Kilo = 1024 (not 1000). This complicates our lives a little. The KB/s equivalent of 33.6Kbps is 4.1KB/s (33,600 / 1024 / 8, allowing 8 bits to every Byte). Therefore the absolute theoretical transfer rate (of non-compressable data) for a 33.6K modem would be 4.1KB/s (in practice about 3.7KB/s would be the limit for such a file).

Between 3.3 to 3.5KB/sec is the minimum you should anticipate from a 33.6K modem when downloading a pre-compressed file - assuming off-peak hours and good conditions.

With compressible files (like text files) you should achieve rates two to three times these rates - depending on the compressibility of a particular file. Web pages are a mixture of pre-compressed graphic files (.gif, .bmp, .jpg, etc) and compressable HTML files, so you should exceed 3.5KB/sec when accessing these pages - they vary enormously.

Compressed file downloads for a 28.8K modem should average about 2.9 to 3.2KB/sec (1.6KB/sec for a 14.4K modem). Downloads with a 56K modem will probable max out at substantially less than 5KB/sec (most phone lines can not cope).

If you regularly get less than the above, then you urgently need to attend to your software, your software settings, your phone line, and/or consult your ISP.

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What to look for

Many items are involved in the search to improve download times. There is little we can do about the Net - except using off-peak hours and avoiding slow sites. There is also little we can do about our ISP - except talking to him, or trying another! However there many important matters at our end.

For many users the most important items will be the Serial Port and modem Maximum speeds, and especially the TCP/IP settings in that order. Also the quality of the phone line (line noise) can greatly affect transmission rates and even the survival of the connection itself. All these assume the Dial-Up Networking and Network settings are correct.

It must be remembered that a mere 0.75Kb/sec average increase will represent a massive 30% overall improvement in download times for many users. Some users have reported a 200 - 300% improvement!

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Three speeds are involved

1. Connection Speed can not be increased This refers to the rate at which your modem communicates along the phone line with your ISP's modem. Its highest speed is totally determined by the manufactured rating of your modem (and your ISP's ability to service that speed e.g. can he service a 56K connection?).

This speed CAN NOT be increased above its manufactured rating, though it may be reduced automatically in order to maintain the connection under poor conditions e.g. line noise or a very busy ISP.

The next two speeds relate to what happens to data passing in either direction between the computer and the modem (including internal modems). Both of these can, and should, be altered according to your needs. Having the correct settings is vital for optimal performance, and sometimes for even maintaining the connection. It is also important to set these correctly in order to gain from TCP/IP optimization.

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These two speeds can, and should, be altered.

2. Maximum Speed: (modem to and from computer)
This is the speed at which the modem communicates with the computer. This modem-to-computer link usually carries much more data than the ISP's modem-to-Your modem and hence requires a higher speed setting.

3. Port Speed: (Serial COM Port)
The Serial COM Port Speed sets the speed of data passing through the Serial COM Port, and is between the computer and the modem. Obviously a higher setting is best (provided the computers are able to cope with that speed, and the majority are).

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Transfer Control Protocol / Internet Protocol

The Internet is run and used by a large variety of different types of telephone systems, computers, operating systems, communication software, and browsers plus e-mail clients.

To function under hugely varying circumstances, it needs to have a set of International Agreements - these are the Internet Protocols (IP). Any system that complies with these rules will be able to communicate over the Net with a totally different set-up.

When you 'go online' there is an initial period of agreement-making (Handshaking) with your ISP and some of your settings are agreed. These request that data be sent to you in a specified manner.

All will be well if you use Internationally recognised Internet Protocols for a PPP connection (Point to Point Protocol). If you do not, then data transfer will suffer - as occurs when Windows 95/98 users connect over a phone line (that's a PPP connection).

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TEST your DOWNLOAD speed NOW [1]

If you want a rough guideline on the download speed of your modem connection, you can download the following two test files. Neither of these file do anything. Test at off-peak hours for both the download site and your own geographical region.

Right-click the file, and select Save File AS, and time the download as best you can.

The first file, test1.txt, is an compressible 75KB text file - it is very compressible for sending (WinZip would compress this text file to less than 1KB).
The second file, test2.exe, is an uncompressible 75KB file composed of randomized characters i.e. it is unlikely to be further compressed (it does not Run). Test with both.
From Europe GMT time zone:             From USA (Western):
test1.txt              test2.exe              text1.txt              text2.exe
To establish the average download speed divide 75 by the time taken (seconds),
and the result is the average download speed in KiloBytes per second.
For example 75 ÷ 22 secs = 3.4KB/sec      

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TEST your DOWNLOAD speed NOW [2]

Third Party Testing

If you are feeling a little lazy and would like free, automatic, download speed testing with better(!) downloading test results, you can try at:

Bandwidth Forum
Modem Speed Test Page
Lucas Arts FTP Site

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Internet Service Provider

Your ISP

Your ISP is very important to your connectivity. He is your point of access to the Net and all of your activity passes through him. Downloads (including Web pages) follow the route: Hosts (many) - Routers (many) - ISP (one) - Yourself.

Many ISPs offer a free 30 days trial period. If you suspect the service of your present provider, then it may be worthwhile taking advantage of one of these trial periods to see if you can get a more satisfactory service from another source.

Do not jump to conclusions. That ISP is very important but is only one of many possible causes of slow downloads. If Web access is not satisfactory at off-peak times, and you are fairly sure of your modem, it related settings, and your phone line, then think ISP.

ISP's get a fee for their service. They have to purchase bandwidth, modems, and servers. They pay employees, rent, and have financial arrangements with telephone companies. Does your ISP have adequate Bandwidth, Modems, Server, Support?

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TweakHomePC Opinion: The accurate transfer of Net signals requires a sturdy, yet delicate, and reliable transport conduit, and the ordinary phone line is most unsuitable in this context. We need to establish a worldwide transfer-vehicle that is accurate, reliable, fast, inexpensive, and capable of vast expansion.

So who will provide and finance all this? Politicians are not renowned for their immediate response rate. Civil servants live in a 'static' environment. Advertising has, to date, been a disappointment for many businesses.

The advent of increased Net security and direct Internet selling of both goods and services is likely to provide the required stimulus. Business will act independently and/or with the politicians to provide a service that will be acceptable to most of us.

A large caveat will be the cost of service. If the potential home market is accurately accessed then the cost should be acceptable - it could even be free. If, however, the emphasis is on the business sector then the cost to home users may be too high.

We live in hope!

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Connection Speed The speed a modem connects along the phone line. This speed can not be increased for that modem. e.g. a 33.6 modem connecting at 33,600 bit per second

Transfer Rate The rate at which a modem can relay / receive data along the phone line.

Maximum Transfer Rate The theoretical maximum Transfer Rate of ALL data achievable with a modem (under absolutely perfect conditions). This will include data resends. [3.5Kcps for 28,800 modem] [4.1Kcps for 33,600 modem] [receive 6Kcps for 56,000 modem - in theory!]

Effective Transfer Rate * The real-life transfer rate of NEW data (resends are excluded). This will always be lower than the Maximum Transfer Rate because of phone line, and other, conditions. THIS IS THE RATE THAT COUNTS. It represents the download rate of the data requested.

Character This consists of 10-bits (the normal 8-bit data byte plus a start bit and a stop bit).

Packets A requested item is transmitted in many, very small and equally-sized, portions called Packets. Each Packet is composed mostly of requested data (plus a header containing an ID number, source and destination addresses, and error-control data). An Internet protocol called MaxMTU (or IPMTU for Windows 98) defines the size of these packets. It is vital to remember this simple principle.

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MaxMTU or MTU Maximum Transmit Unit is the maximum packet size to be sent or received. It is Internationally accepted as MTU=576 for a PPP connection, and MTU=1500 for LAN

MSS Maximum Segment Size is set automatically by Windows at the selected MTU minus the 40 characters used by the header/Footer i.e. MSS=MaxMTU-40 (576-40=536 for a PPP connection).

IP Header Compression Removes the 40-byte Header

RWIN or RecWIN The data Receive Window is size of data (number of packets) that will be received before an ACKnowledgement of safe receipt will be send back. It is therefore a multiple of MSS when using IP header compression . Usually set to 2144 (4 * 536) or 3216 (6 * 536).

IPMTU This is the Window 98 (& DUN13) equivalent of Windows 95's MaxMTU. It is a dynamic setting with a default of IPMTU=1500. Microsoft say it will detect a slower connection (a phone line) and adjust itself downwards to IPMTU=1000, then to IPMTU=576. In whom do we trust????

Packets A requested item is transmitted in many, very small and equally-sized, portions called Packets. Each Packet is composed mostly of requested data (plus a header containing an ID number, source and destination addresses, and error-control data). An Internet protocol called MaxMTU (or IPMTU for Windows 98) defines the size of these packets. It is vital to remember this simple principle.

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Please remember that you alone are responsible for the consequences of any changes you make to your computer hardware or software.

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