DSLAM upgrades, line speed, and stability

[moron51]

A question for all those marginal, far from the exchange ADSL connections.
Now that Telkom is generously upgrading 384kbps users to 1 Mbps, what happens to those whose lines were stable at 384k, but now fall over at 1 Mbps?
Does every such user need to ask for their line to be downgraded again?

And what about the rumours that Telkom's new DSLAMs are less able to handle the higher noise and attenuation at long line lengths than the old-generation DSLAMs? If this is the case, does it not make sense to keep the marginal users on the older DSLAMs, freeing up space on the new faster DSLAMs for those close enough to the exchange to benefit?

MSANs will solve these problems for high-penetration areas in due course, but in the interim, and for the rest of us, is there a plan?

 

[Tim the Techxpert]

Hi moron51,
I read your post and it set me doing some thinking that we are at times taking ADSL for granted and that maybe we don't understand ADSL and how it works or that the router technology has changed. I did some digging and found a great explanation of ADSL which I put on the TecxperTim site here.
Now my interpreting this is that if you have a reasonably modern modem not one from ADSL day one then the modem is going to automatically sync to the point where you are getting stable response.
You may want to get your attenuation and noise ratios from your modem and use them here to see if you will get 1MB when the upgrade happens.

 

[Pada]

Tim, you could do with font formatting on that mydigitallife page of yours!

moron51:
I'm pretty sure that there will be people who are going to be upgraded from 384kbps to 1Mbps and then they'll have to ask Telkom to downgrade them again. If your downstream line attenuation is 60dB or higher then you'll most likely have to do it when Telkom upgrade you to 1Mbps.

Some ADSL modems allow you to set a target SNR (signal to noise ratio or noise margin), and then it will automatically decrease the speed until that target is met. Like with my D-Link DSL-2500U I can go into its console and execute a command to change its target SNR. This is pretty advanced stuff and I certainly won't recommend that route for the average ADSL user!

I haven't heard of the new DSLAM's being less capable of handling poor ADSL connections at all. What I do know is that some ADSL modem chipsets work better than others - like in most cases in South Africa the Broadcom chipset works best.

 

[Roman4604]

What I do know is that some ADSL modem chipsets work better than others - like in most cases in South Africa the Broadcom chipset works best.

From what I've seen, the MSANs report that they use Broadcom chipsets themselves.

 

[moondoggie86]

Sigh My line went down for about a week last month. After it was fixed I was connected via ADSL2+ (previously G.DMT) but still with bad line stats (Line Att 63 and 31 DWN and UP respectively).

Well my line went down again last week Wednesday. Technician came out today. My line was fried and he installed a new line for me. Unfortunately I'm back on G.DMT, bad line stats, unable to sync higher than 384kbps and no connection.

Was so looking forward to being upgraded to 2Mbps

 

[HavocXphere]

I haven't heard of the new DSLAM's being less capable of handling poor ADSL connections at all.

I'm guessing its a reference to the sharp drop in speeds you see on graphs that plot Speed vs Distance for the various ADSL techs. ADSL2+ crashes much sooner & sharper than the others.