2km Over Twisted Pair?

So I found some great discussions on long-distance ethernet via EoC, but what about over twisted pair multicore? I have two sites linked with about 2km of telco line (cat3 or maybe cat5e, I didn't get a chance to look too closely); I've used EoCs over straight copper with baluns, but only short distances, and I wouldn't want to assume it would work at that range, so... suggestions for proper devices would be appreciated.

And no, I can't just put 20 switches along the route ;)


Matt,

You will need to looks at some VDSL devices. Comnet makes some units that can transmit 3KM over twisted pair wiring however you will not get very fast transmission speeds. You could also look at bonding multiple VDSL connections to increase the speeds. What kind of transitions speeds are you looking for?

ADSL / VDLS is going to be an asymmetric connection, and the more pairs you have access to you can aggregate your speeds. 5mb x 1.5mb at 10,000 is about the best you can get... investing in a real DSLAM will aggregate all of the pairs. Having a buried link 2.1Km long between two free standing buildings is really odd. If this is an abandoned Telco link, you should expect to find some Telco cans along the way. especially if these were T1 links from days gone by. My guess is you can buy a wireless link, get much better speed, and avoid so many unknowns about the cable quality.

One site is a water reservoir, the other is a pump station and pressure relief valve down the hill from it. I don't believe there's line-of-site available. The pump station either has or will be getting a DSL internet connection; it looks like the 2km cable is newer direct burial and my understanding is that it was just pulled in, probably replacing an old telco line.

There will also be a wireless link (UBNT AirGrid) between the reservoir and another several KM away; each reservoir has a small NVR and two cameras, as well as an alarm and a Viscount "nanocube" access control module that are currently running stand-alone.

Currently the output relay on the nanocubes, and an intrusion switch into the wells, tie into the SCADA system that relays data back to the city works yard, one input for the switch indicating the hatch has been opened, another to signal that a valid fob has been swiped (it doesn't actually GRANT access, it's essentially just replacing a keyswitch that used to "disarm" the alert). There's generally up to a 10-minute polling delay with SCADA though, so the hope is that all three will have internet access from the city works yard... not necessarily to live-stream the cameras or record off-site, but just to have access to them if necessary. Of course, it would also facilitate adding/deleting fob users from the connected sites without needing to visit them.

We've looked at a wireless link direct back to the works yard, and there SHOULD be line-of-sight from one reservoir or the other... MAYBE. The SCADA system relays through several different sites to get back there, though, and matching that path with the UBNT wouldn't be practical. We figure since the pump station will have internet, and already has a wire in place to one reservoir, it would be silly not to investigate linking the two with that.

check out ME0010A-VDSL from black box. This should get you 5/2mb speed, suitable for the lower end if cameras.

Hi guys, I have used Patton's Ethernet extenders over twisted pairs in the past, pretty good devices, several models available to suit your needs.

I've used a Network Video Technologies (NVT) unit for a similar distance (NV-EC1701). NVT has a calculator on their website (under product support) you can download to see the distance vs. speed you can expect for various cable types. I was skeptical but the product worked quite well on a recent project.

Hello Lisanne:

The NVT NV-EC1701 is an ethernet over coax module, not a twisted pair extender. The OP is specifically looking to use twisted pair cable.

Sorry I mixed up the product number as we evaluated both, I meant the TBus series NV-ET1801 (If you add a "U" to the 1700 series there is an adapter for two-wire, but only suitable for shorter distances).

I am confused. The OP is looking for 2 km (6500+ ft), and that NVT unit only has a range of 2000 feet? I am incorrect?

Ah yes, you're correct, I thought he was looking for 2,000ft. Disregard my suggestion.

FWIW, I've done the DSL modem thing in the past (at one point, you could even order a "dry pair" from the telco in a lot of places between two locations), and it works pretty well. Throughput is inverse to distance, but you can get a couple of Mbps over a fairly long range.

That would probably, IMO, be the best option to pursue initially.

Matt the ComNet CNDE2EOC are dual VDSL units which will get you apron 5.5MB Up / 5.5MB Down on a 2KM connection or you could set them up to get 10MB Down / 1MB Up. If you don't require these speeds you could look at the CNFE1EOC-M which will get you 5MB Up / 0.5MB Down.