Some questions on Interleaving

Lucutus

As I understand it, high interleaving is set on Eircoms 7.6Mbps BitStream available to resellers. This makes latency times around 60ms to local IP addresses.

How can a customer have this changed to low interleaving, and maintain a higher bandwidth throughput, eg. > 7Mbps? This would give latency times of 12-15ms to local IP addresses

Is it true that low interleaving can only be enabled on 3Mbps? If so, what is the reason behind this?

Are there any other limiting factors which block the adjustment of interleaving settings on any DSL connection?

Thanks for any insights.

Snaga

From a purely technical standpoint - interleaving can be disabled on any dsl line.

Whether Eircom have a procedure for this or not though - Im not sure.

If the line is short and has few errors - then removing interleaving would have little effect on a line synced at close to maximum speed. (Other than reducing latency of course!).

If your line is prone to interference or burts of noise - your better off with interleaving on. Higher latency is preferable to packet loss!

Your modem stats would tell you what level of errors your seeing (FEC errors), reset the modem and see how fast they ramp up from 0.

Lucutus

Thanks Snaga.

I thought that it could be disabled or at least lowered fro any DSL connection alright. I suspect that Eircom are simply unable or unwilling to allow low or disabled interleaving settings for bitstream.

Line Mode 	G.DMT 	  	Line State 	Show Time 	
	Latency Type 	Interleave 	  	Line Up Time 	00:02:23:26 	
	Line Coding 	Trellis On 	  	Line Up Count 	1 	
		
	Statistics 	Downstream 	Upstream 	
	Line Rate 	4096 Kbps 	384 Kbps 	
	Noise Margin 	20.1 dB 	18.0 dB 	
	Line Attenuation 	9.0 dB 	6.0 dB 	
	Output Power 	2.3 dBm 	0.2 dBm 	
	K (number of bytes in DMT frame) 	129 	13 	
	R (number of check bytes in RS code word) 	12 	16 	
	S (RS code word size in DMT frame) 	1 	16 	
	D (interleaver depth) 	64 	4 	
	Super Frames 	506218  	506215  	
	Super Frame Errors 	0  	0  	
	RS Words 	34422890  	2150912  	
	RS Correctable Errors 	0  	0  	
	RS Uncorrectable Errors 	0  	0  	
	HEC Errors 	0  	0  	
	OCD Errors 	0  	0  	
	LCD Errors 	0  	0  	
	ES Errors 	0  	0 

I'm not seeing any errors in these router stats.

Is there anyone from Eircom, (Grommet, looking at you here!) who might know of other reasons low or disabled interleaving is not available to it's bitstream resellers?

watty

Also if the line has 100s of pairs and many users have DSL the interleaving HAS to be higher for higher speeds.

Every DSL user in a multi-pair from exchange to street cabinet increases noise for adjacent wires and all pairs slightly.


This is why with time (more subscribers added in an area) your SNR may get worse gradually.

Snaga

With a downstream attenuation of 9db you are within a few hundred meters of the exchange (Shame your stuck on ADSL1). Unsuprisingly theres no errors so turning interleaving off would not cause you any problems.

Now all you have to do is find someone who will turn it off for you

Lucutus

Snaga wrote: »

Now all you have to do is find someone who will turn it off for you

lol, you mean the hard part?

Thanks Snaga

Praetorian

I only just changed my own line from Magnet to Eircom because Magnet were unable to reduce my interleaving whereas Eircom are now do it upon request if you get speaking to the right person.

It's an issue for Comreg really, but they haven't bothered to even acknowledge my mail.

Lucutus

What package/downstream are you on Prae?

Illkillya

Praetorian wrote: »

if you get speaking to the right person.

That's the problem... I spent a few days battling with people in Eircom broadband support a few months back. Their technician said he could see the "interleaving" slider that went from "high" to "low", but no "off". So when it was on high, my ping was high (can't remember exactly, say 50ms on first hop). When it was put to low, my ping was still too high (30ms first hop) for Quake. Downgrading to 2 meg (which is the same package as Eircom 3meg) made no difference. I had to downgrade to the 1 meg package in order to get low pings (<20ms on first hop).

Lucutus

See, that's just the thing. If it's technically possible to disable interleaving for *any* DSL connection, why should the customer have to downgrade their connection to a lower downstream rate in order to have interleaving disabled?

My issue is that BT (my provider), can only configure/request users to be setup on 'profiles' based on their prequal test and that they claim interleaving cannot be disabled or even set lower on the 7.6Mbps profile. As this is provided to them by Eircom, surely Eircom can easily provide a profile at 7.6Mbps with the ability to disable interleaving for those who request it?