I have two semi-related questions:

What do I look for in specs to identify ADSL2+ modems capable of supporting line-bonding? I can't seem to locate any clear indication of those which do versus those which don't.

Update 1: ITU G998.2 seems to be the standard relevant to ADSL line-bonding. Is that usually mentioned in the advertising of qualifying modems?

Regarding a prospective VDSL connection, the distance from the ISP telephone exchange to my home is 1.6 KM as the bird flies. Is it likely I can get near the advertised speeds of 10mbps down/5mbps up based on physics alone? The ISP have no CPEs for rent at the moment, and the market availability is close to nil, except for Asus DSL-N66U. That's an expensive modem. I want to know if VDSL can deliver at that distance befoe I buy the modem and apply for a VDSL connection. My research did not yield unambiguous answers.

Update 2: I had an ADSL2+ - 2mbps Down/0.5mbps Up - connection installed using an ISP-rented modem. The downstream SNR is in the mid-30s, while the upstream is 42 dB. The line attenuation downstream is 19.8 dB while upstream is 7.6 dB. Can VDSL viabiity of 10 down/5 up be inferred from these numbers?


  • Basically any modem connected to a router that supports bonding will do (or a Linux computer with multiple NICs). It's kinda strange that they don't do SDSL instead though. – user256743 Sep 24 '14 at 18:52
  • So there's no "line-bonded" modem as such? – Gyan Sep 24 '14 at 18:55
  • It's a modem/router combo that supports bonding. – user256743 Sep 24 '14 at 18:56
  • I don't think that's correct. I think "line bonding" is done in the modem and bonds the two lines to form a single channel at a lower level than the router operates. – David Schwartz Sep 24 '14 at 18:59
  • Right, so what should I search for or look for to identify a modem as line-bonding ready? – Gyan Sep 24 '14 at 19:03

Old question, but may as well answer it. Anecdotally line bonding never seemed all that successful, we never bothered with it much.

The line attenuation downstream is 19.8 dB while upstream is 7.6 dB. Can VDSL viabiity of 10 down/5 up be inferred from these numbers?

We can get an idea, but will need some more background to be sure. ~20dB dAtten on ADSL points to around 1400m of a run and an ADSL line that should manage 15Mb or more on ADSL2+ (closer to 20 in good conditions). To know what you'd get for VDSL there are two factors we need to know. One, are you getting VDSL from a street cab(closer than the exchange itself) or from the the same racks as your ADSL. Two, does your telco use g.vectoring? That gives a nice big range boost.

Conservatively, going on exchange based VDSL with no vectoring you're talking around 12_1(DS_US) but maybe 15_3, being very conservative. Thats based 17A annex, the "better" annexes use almost twice as much spectrum and can give you a chunk more. Cab launched and you'd be a lot closer and a lot faster.

In any case your teclo should be able to pre-rate lines and give you rough guidelines.

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