Michael Kratz

As many people may be aware, the current state of Broadband in Australia is pretty dysmal, apart from selected exchanges which have been ADSL2+ enabled by carriers such as Agile/Internode (the companies I work for). The majority of ADSL users are limited to a maximum downlink speed of 1.5Mbit, because this is all that Telstra allow providers to offer.

There has been a lot of talk around the traps lately about the issue of Broadband in this country, Telstra’s answer to this was the FTTN (Fibre To The Node) network. Well, as those of you who keep up with the news would know, this was canned a few weeks ago. I was going to write a bit about the FTTN here, but Simon Hackett (MD of Internode and Agile) has already put it in far better words than I would have, so if you want to read up more on the FTTN being canned, see his blog entries: “FTTN is dead, long live FTTN“, and “The Myth of FTTN“.

Anyway, now that the FTTN is out of the equation, what’s next? Well, Telstra could do what they should have done years ago, and release the restrictions they’ve put on ADSL services since they started selling them. To be clear and to fill in the gaps for those who aren’t familiar with ADSL. The original ADSL standard, allows for speeds of up to 8Mbit down and 1Mbit up, depending on the quality of your phone line. ADSL2 supports up to 12Mbit down and 1Mbit up, and ADSL2+ (annex a) supports up to 24Mbit down and 1Mbit up.

Currently, Telstra limits ADSL connections to a maximum speed of 1.5Mbit down and 256Kbit up, regardless of whether the customer could achieve faster on their line or not. To see a graphical representation of exactly what this means and how restrictive it is, see this graph on the Internode website.

Now Telstra seem to be keeping pretty quiet lately about whether they’re going to indeed offer faster than 1.5Mbit speeds to existing users on Telstra DSLAMs. Well, relatively quiet anyway… it appears that they’ve been quietly testing faster speeds on some ADSL services. Possibly with a view of gathering statistics to see what speeds people would be able to achieve if they were to allow access to higher speeds.

A few weeks ago, I was at a place in country South Australia using an Internode 1.5Mbit ADSL connection. Said ADSL service is connected to a Telstra Wholesale DSLAM port. I was in the middle of sending some email, when the connection dropped out. I was using Wireless in a different room to the ADSL router, so being the lazy sod that I am, I pulled up the web interface in the modem to see what was going on. (for those interested the ADSL router is a Billion 7404VGP-M running firmware 5.06)

And this is what I found:

Now theres a few interesting things here. The first and most interesting thing is the downlink and uplink sync speeds. These are in bits per second. So when you work it out, its 6Mbit down, and 640Kbit up. Yes… really! and this is on a Telstra Wholesale DSLAM port. The second thing which is interesting, is that Interleaving is also enabled, Interleaving is used to increase the reliability of an ADSL service, it duplicates and interleaves packets to reduce the likelyhood of packet loss due to bursts of line noise.

It didn’t stay like this for long, and I was quite lucky to catch it really, it was only because I happened to log into the modem, that I noticed it. After about 10 minutes, it dropped sync again, and came back up at the standard 1500/256 speed. Here’s what the stats looked like after it re-synced.

As you can see, we’re now back on the standard 1500/256 profile. The speed is back down, there’s more SNR and the Interleaving is gone.

So there you have it, it looks like pigs might indeed fly and we may yet see higher ADSL speeds from Telstra in the near future. Whilst 6Mbit/640Kbit, is hardly the potential 24Mbit/1Mbit that it could be, it’d certainly be a good start.