VDSL Performance & Tuning

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1140 posts

Uber Geek

Reply # 695990 4-Oct-2012 11:14
nah that's not it. Though where does the bundle of cables go to the top left? This is a master filter (not sure if there are other flavours, but I think this is what they all look like. Maybe someone with more experience can confirm)

varix

90 posts

Master Geek

Reply # 696011 4-Oct-2012 11:25
Ah sorry, the bundle to the top left goes nowhere, it ends just out of sight of the picture. I bypassed this thing anyway as seen here: And this is the result: It has halved my attentuation down to 3db, and increased my current upstream throughput up to nearly 5mbit, speedtest confirms this. It still is showing as 0 for attainable which is odd.

sidefx

1140 posts

Uber Geek

Reply # 696040 4-Oct-2012 12:03
Nice. Wow, that attenuation is very nice. I still think you should be getting better upstream though (and probably downstream with that line attenuation) You can ignore the Attainable display as that seems unreliable on most peoples I think. Current is the one to look at and I'm thinking you should be right on 10360. Can you find where the line comes into your house from outside? The other option is to leave it for a couple of days and see what happens with DLM.

varix

90 posts

Master Geek

Reply # 696043 4-Oct-2012 12:05
Yeah, I was thinking about seeing what would happen with DLM. There is a Telecom box on the outside of the house with some crazy triangle screws on it, this is most likely where the cable comes into the house, as for where it goes from there I am not sure, I might climb up into the roof for a look around when I can get a ladder.

sidefx

1140 posts

Uber Geek

Reply # 696050 4-Oct-2012 12:09
varix: Yeah, I was thinking about seeing what would happen with DLM. There is a Telecom box on the outside of the house with some crazy triangle screws on it, this is most likely where the cable comes into the house, as for where it goes from there I am not sure, I might climb up into the roof for a look around when I can get a ladder. Aha, I'd say that's probably the ETP and that's what you want to look in as the master filter will likely be in there.

varix

90 posts

Master Geek

Reply # 696074 4-Oct-2012 12:32
Just had a look inside it and it just had a black wire that was joined to the blue Cat wire of the house. Will climb up into the roof and have another look for a splitter.

stevehodge

196 posts

Master Geek

Reply # 696153 4-Oct-2012 14:03
varix: Ah sorry, the bundle to the top left goes nowhere, it ends just out of sight of the picture. I bypassed this thing anyway as seen here. ... It has halved my attentuation down to 3db, and increased my current upstream throughput up to nearly 5mbit, speedtest confirms this. It still is showing as 0 for attainable which is odd. That thing is a standard 2 wire jackpoint. There is an extension off it which you've now disconnected. The yellow cylinder is a capacitor used to split out the ring tone. It's not a DSL filter. It is common for attainable to 0 or something lower than current for upload. Seems to be a bug in the Fritz's firmware. You should be seeing similar stats to mine: So I think your download is a little low and there is definitely a problem with your upload. If you compare your spectrum to mine you can see that you've got lower SNR for the low download frequencies and gaps in the upload frequencies that shouldn't be there: Yours is also showing a line of radio frequency interference (the white line) that may be the reason for the download hit at least. My advice is to get your wiring sorted and then see if you can figure out what the source of the RFI is. If you have a monitored alarm you need to disconnect it from the phone line. It won't work with a naked DSL connection (it needs a POTS line to call out on). Monitored alarms are wired so that they interrupt the phone line, but I'm not sure which side of the filter it would be on. You should locate the filter and the alarm and figure it out. If the alarm is between the filter and the ETP (which is the box with the tri-screws that you found) it could be a problem. If it's wired between the filter and the phone jacks then it should be ok provided you're got the modem plugged into the DSL jack (but since that jack you bypassed has an extension off it I don't think you are using the right jack). You should also check that the filter is appropriate for VDSL2. If it is only for ADSL then that could be an issue. I'd be tempted to remove it anyway - with naked DSL it isn't necessary. So basically if your wiring is this, it should be ok: ETP \| filter---alarm---phone jack---phone jack---.... \| dsl jack---modem If your wiring is this, then I think the alarm is a potential problem: ETP \| alarm \| filter---phone jack---phone jack... \| dsl jack---modem In either case pluging the modem into the phone side of the filter instead of the DSL side is going to cause problems. For naked DSL you can disconnect all the unnecessary jacks and the filter and just do this: ETP---jack---modem

varix

90 posts

Master Geek

Reply # 696255 4-Oct-2012 16:56
Awesome, really appreciate your help guys, I will have a dig around tonight when I get a ladder and drop a post later to let you know how I get on. I am really hoping we come across a splitter somewhere.

varix

90 posts

Master Geek

Reply # 696968 5-Oct-2012 21:49
Ok, so, have traced the CAT5 cable from the jackpoint I am current connected to, all the way to the demarc, there is nothing inbetween, I have tidied up the termination where the modem is plugged into. Very strange results when I resync. Sometimes it will sync up at 42 down and 2 up. At the moment it is synced at 47 down and 7.5 up. Attenuation always stays at 3db. Last night the modem did a resync and changed to DLM3 I think, I have 16MS latency and 0INP. So it has dropped me from DLM6 to DLM3 which is cool, hopefully it keeps going down I guess. Not alot of options left. It is also very strange how I have that RFI spike, I cant see anything that could be causing it, the CAT does run across some power wires but it is nothing serious. EDIT: My latency is actually 14MS down and 16MS up, is this possible?

sidefx

1140 posts

Uber Geek

Reply # 696973 5-Oct-2012 21:59
Sadly DLM3 is actually a downgrade. The ordering in SamF original post is the order DLM will change things I think. Mine did the same as yours originally. Can you trace where the alarm is wired to? DLM-1 1ms 0INP DLM-2 8ms 0INP DLM-4 8ms 1INP DLM-6 8ms 2INP DLM-3 16ms 0INP DLM-5 16ms 1INP DLM-7 16ms 2INP DLM-8 16ms 4INP

varix

90 posts

Master Geek

Reply # 696976 5-Oct-2012 22:05
The alarm is looping onto the other cable that I deleted from the plug I currently have the modem running from. So at the moment it is: Modem--20M of Cat5--Telecom Demarc Could the large amound of resyncs I have been doing contributed to my downgrade? I have not seen hardly any CRC errors on either DLM6 or DLM3 so cant see why it would have downgraded me, unless it just kind of swaps you around to see whats up.

sidefx

1140 posts

Uber Geek

Reply # 696980 5-Oct-2012 22:16
If you're certain there's nothing else connected now (i.e. alarm + all other jackpoints are "on the other side" and now disconnected from the jackpoint you're now plugged into, and said jackpoint goes direct to the demarc) then I would just leave it all alone and see what happens. So there's just a single pair now connected to the modem right? I reckon resyncs (even user initiated resyncs) can cause downgrades. My (completely unfounded, based only on my own connection and limited resyncs + a vague description in the British Telecom patent for DLM) theory is that a resync where the modem immediately tries to reconnect is classified as a non-user initiated resync whereas if the modem is down for a while then that's considered to be user-initiated resync. For this reason my new process when I want to tweak things is: 1) unplug modem 2) make change 3) reboot modem 4) wait 10 minutes or so 5) plug modem back in TBH though as others have already said, you're probably best just leaving everything alone.

varix

90 posts

Master Geek

Reply # 696982 5-Oct-2012 22:18
Yeah I am pretty confident all the resyncs I have been doing have probably not helped, especially considering I have been doing them pretty much from day 1. I will leave it all alone for a couple of days and report back to see how it is getting on.

stevehodge

196 posts

Master Geek

Reply # 696983 5-Oct-2012 22:21
varix: Ok, so, have traced the CAT5 cable from the jackpoint I am current connected to, all the way to the demarc, there is nothing inbetween, I have tidied up the termination where the modem is plugged into. Very strange results when I resync. Sometimes it will sync up at 42 down and 2 up. At the moment it is synced at 47 down and 7.5 up. Attenuation always stays at 3db. 47/7.5 is pretty reasonable though your upload speed should be the max possible. But that degree of variability is not right IMO. If it were me I would talk to Snap and get a fault logged with Chorus unless Snap think it's not worthwhile. What does your statistics page look like (particularly the CRC errors). It didn't look like you were getting many errors before but perhaps they are happening in bursts. Something has made DLM downgrade you. EDIT: My latency is actually 14MS down and 16MS up, is this possible? Yes, they are measured values and do sometimes vary a bit from what DLM configures.

varix

90 posts

Master Geek

Reply # 696984 5-Oct-2012 22:25
Hmmm, this is an hour of uptime: I have seen the CRC errors go up to about 0.01 at the most, most of the time it is on 0. Hopefully DLM will settle down now that I am going to stop restarting the modem 5+ times a day

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