ADSL2+ Interleave vs fast path mode

[cavedog]

So my line was always syncing with Fast Path mode and has recently changed to interleaved.

I did some research and since the only other country using ADSL like SA is Australia. They say that interleaved causes a dslam ping time of 30ms+ which I am currently seeing compared to fast path which has a 1-7ms ping time on the dslam hop.

What I can's seem to find out is how exactly this affects my line in terms of speed stability and what is the difference of the two modes? Are there a specific one that is better?
I did read they say the line usually syncs on interleaved when the upstream SNR is low? My upstream SNR is lowish @ 7dB where it usually was like 8dB+

Fast Path mode previously:

Same line same speed now:

 

[Haterade]

We have interleaving turned on over here in Namibia too by default. It is supposed to help noisy lines with stability by rearranging bits before they're transmitted so that errors can be detected and possibly corrected (But this process obviously takes a few ms). I personally don't see the point of having this enabled on my line because I live right next to a DSLAM, but my ISP (Telecom Namibia) refuses to disable it.

 

[blaaislaai]

I happen to be using the FAST one, lucky me i guess

Tx System: ADSL2+ No Defect Fast

 

[cavedog]

Thanks for the info. This is strange and I think Telkom made a adjustment to my dslam.... I do have a 10Mbps line at the same property connected to the same dslam and it is using fast path. My main line which syncs @ 13Mbps which is actually the up to 20Mbps service is always on interleave.

I did also notice that Telkom like @Micky I think it was said introduced a setting to refuse the SNR to drop below 6dB. I force my router to drop the SNR below 6dB by setting the target SNR via telnet but after the the resync the line still does not increase in speed and drop the SNR anymore. This only started happening when my line mode was set to interleave and it was possible to do the changes when it was on fast path.

Fast path caused some hec errors which caused latency spikes. Now since on interleaved the latency is more stable but slightly higher by about 30ms.

I also see now that the mode has changed from Fast path to Interleave that it is now correcting errors but there are still some uncorrectable errors which I guess will cause packetloss and then latency spikes....

This is a very interesting development from Telkom and wonder if they dynamically set the line to interleave when they detect that the SNR is below a certain level.

 

[ScottulusMaximus]

AfriMan was saying this(the line sync) is the reason their "Tweak My Line" tool has disappeared, Telkom automatically adjust your speed to your line stats.

Apparently takes a week to reset it if you don't like paying for a faster line and the computer decides to turn it down..

 

[Haterade]

It shouldn't be problematic for most internet users. A few gamers will however be irked by the extra 20-30ms of latency, especially those playing on international servers. For their sake I hope Telkom will give their customers the option to disable interleaving.

 

[cavedog]

I did some testing now and there is no real advantage of having interleave mode instead of fast. If you have a uncorrectable error on interleave is would still mean a latency spike.

It would be interesting to know why Telkom did decide to do this first of all. Then it would be interesting to see what Telkom see as a low SNR before they change you to interleave.

These technical changes are being made while first line support or any type of support channel does not have a idea what is going on or what you are talking about when questioned about it.

So basically they changed 2 things. Hard capped the SNR to 6dB minimum so the SNR tweak no longer works and the introduction of the interleave mode for low SNR adsl lines.

 

[HowTo]

@cavedog

I'm a fair distance away from the exchange. at least 4km.
My SNR numbers were 5.5 fine for the interim. It only started 2 months ago that I get line drops while gaming.
I requested my speed to be dropped from 4mbps to 3mbps. The SNR number increased from original 5.5 to (6.8 to 10).
I still get latencies spikes while gaming.

Don't know what this means could also be my problem.

Fast path caused some hec errors which caused latency spikes. Now since on interleaved the latency is more stable but slightly higher by about 30ms.

 

[Mr.Jax]

Yup, exact same happened on my line. I think I was switched to interleave some time last week.

Latency doubled.
Downstream SNR worsened....almost half of what it used to be.

Very P*ssed off about this.

TelkomZa ignored my PM too it seems :/

 

[Mr.Jax]

....

This is a very interesting development from Telkom and wonder if they dynamically set the line to interleave when they detect that the SNR is below a certain level.

Nope.

My SNR was 14dB downstream; 12dB upstream which is considered pretty good, yet I was still switched to interleave.

 

[cavedog]

Nope.

My SNR was 14dB downstream; 12dB upstream which is considered pretty good, yet I was still switched to interleave.

Then I wonder why they set it to interleave. It can't be random but there has been no word from atelkom at all so I don't know. My 13Mbps line is still on interleave and my 10Mbps line at the same property connected to the same dslam is fast path....

 

[Mr.Jax]

Just got word from TelkomZA:

"Telkom in the process of implementing a new platform to manage ADSL stability, it`s called "DSL ASSIA", looking at your service it has already been optimized by the system. "

 

[Mr.Jax]

This looks like the product that Telkom is implementing to automatically manage DSL sync etcetera
http://www.assia-inc.com/products/dsl-expresse/

Edit: this certainly looks like an awesome product which will undoubtedly improve ADSL speeds and stability for many users.

..but I still want fastpath back please; the product shouldn't break something that wasn't broken in the first place

 

[Impulse_One]

I happen to be using the FAST one, lucky me i guess

What's your line stats?

 

[cavedog]

Looks like sometimes my 10Mbps line gets moved to Interleave then if I restart the router it is back on Fast path...... My 13Mbps line is on interleave permanent no matter what I do.

 

[cavedog]

Downgraded my 13Mbps line to 10Mbps yesterday and the change only took place now and the line changed back from interleave to fast path. Line is much more stable but still seeing some hec errors. Will have to log a fault with Telkom.

 

[blaaislaai]

I spoke to soon, since today mine is on INTERLEAVE.. :/

 

[cROSs]

I had the same problem (and being a gamer myself, that extra latency was driving me insane) and calling my isp or telkom didn't help at all.

However after getting in touched with TelkomZA (pm on mybroadband) my line is fixed, he replied:
"Have made some changes to the sync profile, would appreciate if you could test and advise if latency has improved.
Regards
Charl Olivier
Telkom Social Media Team "

I suggest u all do the same

~cROSs

 

[blaaislaai]

I PM'd TelkomZA here on mybb, got a phone call and he only changed my sync mode from "Multi-mode" to "ADSL2+" and still stuck on interleave on my 10mb line.

 

[cavedog]

I PM'd TelkomZA here on mybb, got a phone call and he only changed my sync mode from "Multi-mode" to "ADSL2+" and still stuck on interleave on my 10mb line.

I don't think that this interleaved is linked to a low SNR. I'm still trying to figure out what the hell triggers interleave mode to activate.

My 13Mbps line was stuck on interleave. Then I downgraded back to 10Mbps and it changed to fast path. My other 10Mbps line has a SN of 5.7dB and it is also on fast path so isn't SNS related.

It is a automatic switch over though.