[LINK] Australia Gets Broadband – A Slow Connection For A High Price

[steve jenkin]

Richard Chirgwin wrote on 13/7/07 5:36 PM:

Richard,

Calling Janet's comment, and by inference her, 'stupid' is offensive and
uncalled for - especially on the very first post in a thread.   It
doesn't progress any debate, inform or educate anyone and it's a
positive dis-incentive for others to post.

Your turn of phrase diminishes the whole of the LINK list.

Especially when what you post:
- is ambiguous and undefined
- incorrect in many senses

and you confuse different concepts.
> Eeeek! What a shockingly stupid statement.
>
> 256 Kbps is a best-effort service.
> 512 Kbps is a best-effort service.
> 8 Mbps is a best effort service.
>
Remember Frame Relay? [No, I'm *not* saying ADSL services provided by
ISP's is 'Frame Relay']
<http://en.wikipedia.org/wiki/Frame_relay>

It's got a couple of key concepts that apply to ADSL services:
- Access Rate - the signalling rate on the customer tail
- Committed Information Rate - the min. bandwidth guaranteed at all
times to customer by the service provider

The Access Rate is strictly on the link from the customer premises to
Exchange/Network Access Point.
The CIR is an end-to-end rate across the full Service Provider network.

Telco and ISP's provision services with an 'over subscription' rate [or
number of times over subscribed].
This applies at the Telco/ISP network level - links overseas,
interconnects and even DSLAM links back to the ISP's backbone network.

Janet was quite clearly saying that Telcos will only guarantee for ADSL
a line or access rate, that's the signalling rate from customer premises
to DSLAM, up to 1.5Mbps if you are no further than about 8km from the DSLAM.
None of this references line-errors or link throughput - nor the
stability/usability of the service.

Telco's offer a higher rate service, that Janet was referring to, with a
non-guaranteed signalling rate and a potential maximum profile of 8Mbps.
[If fact, ADSL or ADSL2+, they will only guarantee 1.5Mbps].
On top of different rate plans, Telcos, e.g. Internode, offer a range of
different ADSL profiles varying in speed (upload/download), stability
and latency.  They generally have one referred to as 'Thrillseeker'.

Janet used the term 'best effort' to describe the non-guaranteed nature
of the ADSL customer-loop above 1.5Mbps.
It wasn't misleading or confusing...

You've switched from talking about the customer-line access rate
(Janet's area) to realised Network Throughput.
And used a term, 'best effot' that probably isn't in any contract or
technical description.

And the rate a customer can realise varies wildly, depending on their
location in the network, the remote end location and the network path
required:
- we talking upload/download?
- local, intracity, intrastate, international, ...
- 'On Network' for the ISP
- via peering services
- time of day, events, ...

All of these are affected by interference, lost packets, routers,
congestion, temporary equipment/link failures, ...

And then there's the crux of the matter - the server you're talking to
and protocol stacks you're both using.
If it's a dog and runs incredibly slowly, then nothing in the network
will help.

The IP protocols themselves guarantee nothing...
There are a bunch of RFC's that define "Quality of Service" and related
network management and performance issues.

Any IP-based network can make very few guarantees, especially on busy
networks.
Google spend a lot of time and effort dealing with strange network and
routing problems every day. But to everyone it still appears 'To Just Work'.

So when you say "Best Effort" without clarification, it doesn't show any
knowledge or appreciation of the field.

regards
stevej

-- 
Steve Jenkin, Info Tech, Systems and Design Specialist.
0412 786 915 (+61 412 786 915)
PO Box 48, Kippax ACT 2615, AUSTRALIA

sjenkin at canb.auug.org.au http://www.canb.auug.org.au/~sjenkin