Interleaving

Since Openreach have pulled out of upgrading our exchange area for FTTP, and some neighbours have objected (for some unknown reason) to Virgin Media cabling our flats, I am stuck with FTTC for now.

I like gaming, therefore, I like low latency.

Is it reasonable to request to my current SP to remove interleaving from my line? Is it possible?

It isn't a request that can be actioned on FTTC.

The DLM is 100% automated and no ISP has any manual control.

It shouldn't be an unreasonable request, but with the system as it is it is impossible.

Edited by j0hn83 (Sat 15-Aug-20 13:14:31)

In reply to a post by foxtrot_yankee:

I like gaming, therefore, I like low latency.

and Virgin for that may not be the answer. Depending on the area, you could find that your latency (and jitter) is far worse than your current VDSL.

Matt

In reply to a post by uno:

and Virgin for that may not be the answer. Depending on the area, you could find that your latency (and jitter) is far worse than your current VDSL.

Matt

Virgin definitely has a higher latency than OpenReach VDSL for me, and that's in a brand new Virgin Project Lightning FTTP (RFOG) area.

The 8ms delay added by Interleaving on OpenReach VDSL would make Virgins minimum latency a little lower.

Virgin has pretty horrendous jitter though so I would rather have an Interleaved VDSL line.

My Virgin BQM

I'm in the Edinburgh area and got a minimum 20ms with Virgin.

Latency has varied slightly between ISP's on OpenReach's network, so a change there can help.

On Talktalk FTTC the minimum latency was around 18ms.
On Plusnet FTTC the minimum latency was 17-18ms.
On BT FTTC the minimum latency was always 16ms.

I just moved to BT FTTP and the minimum latency is 14ms.

My BT FTTP BQM

So a 2ms drop in latency going from VDSL to FTTP (GPON).

If DLM has enabled interleaving that is because of the error rates on your line.

Yes it adds 8ms to latency, or more if things are really bad, but without it the error packets all have to be re-transmitted.

I'm not a gamer, but from what I've read in the past that is worse than having the interleaving overhead.

Have you checked the error rates, and investigated whether or not you can reduce them. Either by changes to equipment or its location, or by reducing the connection speed which AIUI is not as important as latency for gaming. Reducing the speed reduces errors, and if you do that then DLM may relent after a while and restore Fast Path.

Router stats including the error statistics as well as the basic sync/attenuation/noise margin and interleaving values would be useful.

Hopefully this is readable. I'm just over 300m to the cabinet.

DSL Status Information
DSL Mode
ITU-T G.993.2_Annex_B (VDSL2)

DSL Uptime
1 day, 5 hours, 40 minutes and 37 seconds

Line Coding
DMT

Status
Connected

Number of Cuts
0

Link Power State
L0

Line Quality
Downstream Upstream
Current Rate 43636 kbps 9077 kbps
Maximum Rate 56597 kbps 9202 kbps
Signal-to-Noise Ratio 6.3 dB 6 dB
Attenuation DS1 15.4 dB, DS2 42.0 dB, DS3 64.8 dB US0 6.5 dB, US1 33.6 dB, US2 52.1 dB
Power 12.6 dBm 6.8 dBm
CRC Errors in last 1780 minute(s) 118 31
K (number of bytes in DMT frame) 0 0
R (number of bytes in RS code word) 10 16
S (RS code word size in DMT frame) 0.0211 0.8374
D (interleaver depth) 2585 1
Delay 13 ms 0 ms

Downstream Upstream
Super Frames 52442686 7973875
Super Frame Errors 118 31
RS Words 2957936721 510255742
RS Correctable Errors 2624869 118
RS Uncorrectable Errors 7741 0

Downstream Upstream
HEC Errors 1233 0
OCD Errors 1 0
LCD Errors 1 0
Total Cells 375343101 0
Data Cells 232733909 0
Bit Errors 0 0

Downstream Upstream
Total ES 23 354
Total SES 0 0
Total UAS 29 401