broadband

[QuackingPlums]

Ok peeps.

Think of your ISP's big connection to the internet as a motorway, and your connection to your ISP as a sliproad onto it. Each ISP may be connected to a different motorway (and some motorways are bigger than others), but all the motorways lead to the same place.

If you're a home user you'll be on 50-1 contention, or 20-1 contention if you're lucky, which means 50 (or 20) ppl all share your sliproad down to the motorway.

If you're a business and pay lots of money, u might even get your own sliproad.

either way, if the motorway is busy, it don't matter how many people are using your sliproad... you'll still be stuck when you hit the motorway.

So contention issues don't really affect THAT much for most of the time. When it's busy, it's busy for everyone.




(Philip, I don't think you're uncle talks out of his arse... but even the advertised contention ratios for home broadband on BT's website is 50-1... I'm sure SOME lucky buggers have 3-1 or even 1-1 but they probably pay for it? Does your Uncle do home connections or business ones?)


Cable broadband works on a different system altogether, by the way, before I get flamed for this...

 

[Philip]

Thats not his actual job, he's doing it because they are short on engineers. He sits with the servers all day, used to be CCNA, now CCNP qualified.

Its the new way BT are doing things to provide a more stable connection, after last years poor downtime in areas, they fragment the line down somemore in to more channels(like T1). This allows them to reduce the overall downtime to a greater number of people.

 

[QuackingPlums]

Originally posted by Philip
...they fragment the line down somemore in to more channels(like T1).

I'm pretty sure T1s are only broken down if you order a fractional T1...? Wasn't this the principle behind PRI?

 

[Philip]

Quacking, i know what you mean, i do networking myself. I just didn't explain what i wrote in my last post, in my first post....if that makes sense

He's doing home connections...not much call for business lines since the price drop of redundant lines. T3, T1 fractions are also getting cheaper.

 

[QuackingPlums]

Yeah, sorry, didn't mean to sound patronising.

How recently have redundant lines come down? These are those ones that are guaranteed to be separated by a minimum fixed distance all the way to the exchange, right? Have they really fallen below that of ADSL?!

 

[Philip]

Not fallen that much But enough for business' to pay the extra for a more reliable connection. The prices are constantly dropping.

 

[Rabies]

Don't wish to sound pedantic, but the european standard (including what BT call PRI, for some reason) is E1. E1 is equivalent to 30 ISDN channels (hence why most european telcos call it ISDN30) whereas T1 is only 24 channels' worth.

And no, PRI lines are still excessively expensive. It's priced approximately per channel, and rental is about the same for each 64k channel as for 576k ADSL. And that doesn't include connectivity at the other end.

 

[QuackingPlums]

No argument from me there! The number of times I've tried to tell ppl about the E1/E3 standard we use here, not the T1/T3 standard they use in the US... the "principle" i was referring to though was the fractioning into 64kbit channels... (or 56 if you're in the US).

As to the pricing being the same for a 64k channel and ADSL - the "perceived" benefit of course is back to that old chestnut contention...

Also a business line has a guaranteed uptime, with refunds (if u shout long enough) if reliability drops below that uptime... no such luck with ADSL, as we're all too aware of

 

[QuackingPlums]

Philip...

It just occured to be (at 3:30am!!!) what your uncle must have been talking about when he said 3-1 contention - the PVC lines coming from each DSLAM at a BT exchange!

The ATM backbone runs at a fixed speed (currently up to 622Mbps I think) and is shared between BT's subscribers, (ie: ISPs) via Permanent Virtual Circuits (or connections) running at a minimum of 10mbps.

It is these PVCs that are contended 3-1... each connected ISP has the option of contending its own bit of the network at 50-1 or 20-1, which seem the most popular contention ratios on the market today.

There was a time actually when ADSL take-up was slow enough that each ISP was assigned a DIFFERENT PVC... *sigh* probably no longer the case now...

The interesting thing is that these PVCs are NOT a fixed size across all exchanges... whether or not the knock on effects to the end user are noticeable will be debatable...

Man, I gotta go to bed...

 

[Collier]

I like having a buisness connection!

Paul