Which DSL...A or S?

[Bear Cub]

Getting awful confused with DSL.

Company (selling DSL) tells me that an SDSL circuit working at a guaranteed 192 down and 192 up will be quicker than an ADSL circuit advertised as 384 down/128 up (for a domestic net surfer that only "sends" e-mail).

Any truth in this?

[Air Brakes]

In answer to your question, probably yes.

Check this information out before progressing, then check the cost ratio given by each party offering the service. below is a short description of the 2 services

ADSL

The problem with some companies that claim ADSL is the be all and end all of connection options is they are giving you the maximum figures, not the expected figures.

The first question to ask is what is the Contention ratio they are operating. This is the ammount of users connected on the ADSL circuit you are using. The higher the contention ration the slower the connection you experience.

Then you have to weigh up the price against the cost of a standard phone line. As ADSL is always on, so you only pay the monthly connection charge + phone line rental (UK Only other countries may differ).

For a complete explanation in English on ADSL FAQ goto this address paying particular attention to the information about Contention Ratios. http://www.pipex.net/adsl/faq.shtml#content

SDSL

At this web address you can find info out about SDSL, http://www.orckit.com/fr_dsl_faq.html

which according to your supplier could offer you a speed of 192k each way. This would mean he is offering you a contention ratio of 4 to 1.

Pros and Cons

In some cases a guaranteed speed of 192k is faster than a risk of 384k between 20 + users. Check the price and if it is good for SDSL and the contract is not to binding then my recommendation would be the SDSL. At least you can guarantee a speed every time.

[touch&go]

I have had ASDL from BT for a month and I'm happy with it........don't have anything to compare it to only my old 56k modem and it blows that out of the water,

You are on about speeds of up and down loads, don't no to much about that, but I'm connected at 576,000bps at the moment and it work great.

[G-NADS]

I have Iomart / Madasafish ADSL.

An average download is at about 50k/s. I download a lot of files and the minimum I have had is about 20k/s but I once had a freak connection at 240 k/s which lasted for about 10 seconds.

I wouldn't recommend Iomart becuase they take forever installing it. A couple of colleagues had BT ADSL installed within a week of ordering it. So BT would be the better choice!

[Bear Cub]

Thanks for the answers.

G-NADS, your answer scared me. 50K...is that it? Even though it is far superior to my average 3K yes...single digit, three K...it doesn't seem too hot.

Do you remember what you were promised? Was it a 384 downlink..or a 129..or what?

Any idea how far you are from the exchange?...and why so low a speed?

[G-NADS]

The 512k uplink and 256k downlink can work, but only under the best and most perfect conditions - nonsense, it never happens.

It can be liked to that speed achieved by a 56k modem. The modem will allow you up to 56k download but other factors do affect this hence the 3k per sec.

No one and I mean no one will ever achieve a download rate of 512k constantly on ADSL - because the optimum conditions required to do so just do not and will not exist. Only if you are the only user on the damn main server it will!

It's just a selling point really. Although the modems themselves are capable of 2Mb/s!!!! if you can provide the conditions.

Also important to realise is that 56k does not mean 56 kilo bytes but means 56 kilo bits. There are 8 bits in a byte.

http://www.pprune.org/ubb/NonCGI/confused.gif


[This message has been edited by G-NADS (edited 05 April 2001).]

[Bear Cub]

E-mail from the man today said - in answer to the question "You promise 384k maximum - but what COULD be the minimum"....

<<<"A worst case scenario would be below 100K. If this was to happen it would
be a split second. You should be facing an average speed of around 250K.
There is a bit of fluctuation in ADSL. If your connection is continually
slow our Tech Support will be able to troubleshoot with you and correct the
problem.">>>

Do we buy this?

[G-NADS]

Ask him again and phrase the question as:

"What if I download a file (i.e. right click, save target as) and the file was 5Mb big, under the 'current file transfer rate reading' what can I expect to see"?

This is what we are looking at - the actual transfer rate at a given time.

You can do tests at:
http://speedtest.mybc.com/
http://speedtest.inch.com/

My throughput was about 450k/s but actual download rate i.e. file size divided by time taken was 53.3k/s and this is the magic number!