Can you create a LAN IP network using telephone cables?

This article analyses if the single pair copper cable networks, which are available in most of the organizations for providing voice connectivity through a local telephone exchange (EPABX) connecting all the analog phones, can be used to create an IP Network (Using DSLAM, CPE and ADSL2+ technologies), with a limited functionality in special cases.

I know, I need to pinch myself and wake up in the present! In this era of 10GE backbone ethernet chassis switches, Cat x, Fiber cables it is silly to explore a topic that might be outdated by atleast ten to fifteen years! But this can help some factories which are located in remote places and have no effective IP LAN network, but want to have one.

The point to note here is, any company would be having a telephone network. The single pair copper cables would be running to almost all the major places in such remote factories (It is good if they have fiber cables, Cat x cables, but we are discussing the other case – companies that don’t).

What people used to do in earlier days is (some even do now) – they have the Cat x cables to connect the computers in the computer room (or a department) and have LAN extenders which extend this small segment of LAN to other rooms or departments. This used to be the case especially if two departments are situated at a distance of more than 90 meters (as Cat x cables can’t go beyond that distance). They plug in the RJ-45 cables at one end of the LAN extender and connect the single pair copper cable at the other (some times multiple copper pairs) and the same set-up would be repeated at the other department. It seems you get around 2 Mbps of Upstream/Downstream bandwidth with one such inter-connecting copper pair. Well you could send a couple of mails between them and maybe share a couple of files – but that’s it. Generally each department has their own internet connectivity to share only among the local PC’s. There is not much of centralized network or services.

There is an alternate way to do almost the same thing but in a centralized manner by using the DSLAM’s, CPE’s and of course, the telephone cables. This takes advantage of the broadband technology – ADSL2+.

Imagine there is a huge factory (several departments located far away from each other). They have a telephone exchange, a Main Distribution Frame (Where all the cables are punched near the telephone exchange) and single pair copper cables running around the whole factory to give telephone connectivity. Of course these copper cables are bundled in to 20 pair, 40 pair etc while they are travelling around and are separated in the departments. Now, we want to have a functional IP network in this scenario without using fiber cables, cat x cables, switches etc. It is still possible!

We bring in an equipment called a DSLAM (Digital Subscriber Line Access Multiplexer) which is the smaller version of the one that a broadband service provider uses to give broadband connection to homes. We then hook this on in between the Telephone exchange and the Main Distribution Frame (MDF) so that all the lines go in to and out of the telephone exchange (EPABX) through the DSLAM. DSLAM supports direct internet connectivity – you can plug in 1 Mbps or higher bandwidth internet leased lines/ VPN’s directly to the DSLAM. Now let us come to the subscriber side – We need to place a CPE (which is actually a broadband modem) which connects to both the telephone and the computer. Yes, this set up needs to be replicated with every PC which wants to access the internet through the network. That’s it, you have a full fledged LAN IP network that can transmit data along with voice just using telephone cables! And yes, you can use both voice and data connectivity at the same time as this is broadband technology.

Well companies primarily use this to give internet connectivity to all their PC users, but even basic file transfers and email could work over such a network. But the problem with using ADSL2+ broadband technology is, the upload bandwidth is much lower than the download bandwidth. So, if the computers just need to be internet enabled, then this method could be effective. Each PC could get in excess of 10 Mpbs download stream – but that should still be ok, considering that the central  internet leased line capacity is going to be less than that, in most cases.

Of course, this cannot be a replacement for LAN. But companies could use this method as a temporary arrangement (for some companies the temporary period could be even years!) till a full fledged LAN is created using the switches, fiber and cat x cables.

excITingIP.com

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