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[kyoudaiai]

Hello,

recently I've decided to add a second 100Mbps / 10Mbps vdsl line to the house, the 1st line is running @ 100 / 10 perfectly with these stats:

Router: Huawei Hg630
Upstream line rate (kbit/s):10014
Downstream line rate (kbit/s):99999
Maximum upstream rate (kbit/s):45579
Maximum downstream rate (kbit/s):138528
Upstream noise safety coefficient (dB):34.2
Downstream noise safety coefficient (dB):10.6
Upstream interleave depth:89
Downstream interleave depth:1978

However once I've added the second line and connected a 2nd modem to it as it syncs it killed the first line bringing Downstream SNR to 0 points upstream SNR numbers didn't seem to change if at all.

I'm around 200 meters from the cabinet and then the copper runs in an underground patch cable to my house that cable provides around 40 something phone ports since it's only me using that panel my lines run on ports #1 & #2 on that panel, then I've an additional 15 meters of copper running directly to the house into a master filter one for each of the designated lines.

why is crosstalk so severe in this scenario, does anybody have any idea ? or any solution that I can try to have those lines coexist and running simultaneously ?

one thing I've in mind is to try to move the second line away on the panel from port #2 to a port that further away from it. this will  need me to involve the telco as well to reroute the line to the new port on the cabinet. but it's possible since I'm the only tenant on that panel anyway.

looking forward to hear your thoughts.

Regards,

[Weaver]

Welcome to the forum! 

I think Kitz was talking to me about something that could be relevant. If you start up the first modem while the second is off, then start the second modem, the first modem has started in conditions that are far too favourable due to the lack of crosstalk, which is not how things are going to be.

[Ronski]

Surely if its crosstalk the first line should resync taking into account the increased noise caused by the now present crosstalk, thus syncing at a lower rate.

[kyoudaiai]

ok so I tried your suggestion resyncing the first line after bringing the second line online. First line resynced at about 96 / 10 stats below:

Line1:
Router: huawei HG630
Upstream line rate (kbit/s): 10014
Downstream line rate (kbit/s): 96450
Maximum upstream rate (kbit/s): 49004
Maximum downstream rate (kbit/s): 128540
Upstream noise safety coefficient (dB): 19.4
Downstream noise safety coefficient (dB): 0.9
Upstream interleave depth: 89
Downstream interleave depth: 2457


Line2:
Router: ZTE ZXHN168N
actual Rate(Up/Down) 37043/61204 kbps
Attainable Rate(Up/Down) 37119/57740 kbps
Noise Margin(Up/Down) 6.7/5.9 dB
Line Attenuation(Up/Down) 13.8/9.8 dB
Interleave Depth(Up/Down) 17/257
Interleave Delay(Up/Down) 0/6 ms
INP(Up/Down) 0.1/0.3 symbols
Profile 12a
LinkEncap G.993.2_Annex_K_PTM
CRC Errors(Up/Down) 0/0
FEC Errors(Up/Down) 0/0
HEC Errors(Up/Down) 0/0

second line synced at about 60 / 37 I've tried to see how it would perform while line1 is offline it could manage about 80 / 40 but attenuation is much higher than line1 and SNR is much lower so I believe wiring to this port isn't best as both lines are physically exactly the same.

oh btw while I resync line1 it killed line2 for second forcing it to resync again.

my question now is there anything I can do to make this situation a bit better. do you think moving the wire on the port  will help ? right now the line wires are about 1mm apart on the panel then the both wires run the same path to inside the house in 2x UTP 0.5mm copper lines into master filters / splitter then to the routers.

I will attach photos for the telco patch panel on the street to elaborate more.


Thank you in advance.

[Chunkers]

Just our of curiosity have you tried switching over the modems, cables and filters to eliminate them as a contributory factor? Beyond that all I can think of is to go round and check all the connections are properly terminated inside the boxes.  I remember I had a problem once caused by a very old (and bad) telephone cable between one of my modems and the wall.

I have two lines also, they come into the house through the same overhead telephone cable and split in the attic and are separately routed inside the house, they both sync at broadly the same speed about 70/20 (the newly installed one being marginally a few % better)

I hope you get it sorted out!

Chunks

[kyoudaiai]

the 2nd router now being used on line2 syncs almost same, the huawei performs a bit better however when I had that ZTE on the very same line before it synced at the same speeds and same SNR however the DLM didn't like it that much and kept knocking the line down to 90Mbps down stream for whatever reason.

in my scenario despite that both lines have phone capabilities I'm not really using them the wires from the binder on the street just goes into master filter then to and only the modems. the binder itself is using a 48 patch cable that runs underground to the cabinet and that is like over 30 years old. the wires that run from there to my house is new one solid piece of 0.5mm copper UTP cables.

I will try switching the 2nd line to port #25 on the binder that puts it in the far corner from the 1st line. see where that gets me anyway since the circuit on port #2 doesn't seem all that good anyway compared to #1 the telco guys can usually measure wire impedance on these circuits instead of me going by trial and error but well it's holidays here I won't know about that until Tuesday or so.

[Moderator edited to remove the unnecessary quotation of the preceding post.]

[Chrysalis]

Sadly it is what it is, there is a reason vectoring got invented.