In an MDU or MTU, you'll rarely find just one of anything, since you must usually match upgrades in appliances or services in one unit to all the other units. Unfortunately, this "do one, do all" rule can make managers leery of deploying new products or services to their buildings.

This viewpoint can be seen in the reluctance many managers feel toward making any radical changes in infrastructure, especially since MDUs often lack plentiful plenum space. When faced with deploying high-speed Internet access, few people want to string Category 5 cable throughout a large MDU. Even using TV cable for Internet access is often not feasible, as the cable infrastructure in older MDU buildings must be upgraded before it can carry digital data. A cable rollout in such a densely packed environment is usually an expensive, extensive, and difficult job.

However, making use of existing wiring as much as possible can reduce both the cost and time involved in such a project. An ideal choice for providing high-speed Internet access is to use the telephone wiring system, which likely already permeates the building. Current technology can provide nearly the equivalent of an average DSL connection, or about 1 Mbps (megabit per second), over ordinary telephone wires at the same time the wires are being used for voice.

Phoneline Networking and Cable
Reusing the telephone wiring harness for cable Internet connectivity has several advantages over stringing new cable for transmitting data.

Network topologies vary greatly, depending on the type of MDU or MTU. In many offices, for instance, the phone system extends unbroken throughout the building. Such a phoneline harness could connect every enabled device in the entire complex. This could be highly desirable, since it would enable occupants in different parts of the complex to exchange files and data with each other without going out onto the Internet.

By contrast, apartment dwellings and hotels usually have separate phone system connections for each room or suite. Individual tenants should not be able to access resources that other occupants have exposed; their access should properly be limited to Internet, not local, resources. This situation would necessitate a switching or routing device that can connect tenants to the Internet while keeping their data separate and secure.

"The main thing we've been using phoneline networking for is apartment buildings, particularly where we can't run coax through the building because a different cable provider already has a bulk cable contract," says John Hamilton of Black Hills FiberCom, the full-range communications subsidiary of Black Hills Corporation, an energy and communications company headquartered in Rapid City, South Dakota. "We have customers who are getting our phone service and they want data too, so we just run [the network] over the phone lines from the equipment room."

Public Network Connection
In today's wired world, any network's value is limited unless it also provides always-on Internet access, through a device such as a broadband gateway, to interface the phoneline network with the larger public network. In MDUs where every tenant has a separate phone system, such as an apartment or residential complex, this connection needs as much bandwidth as possible so that each dwelling unit can receive the maximum possible bandwidth.

For example, in a home or office with only one or a few phone lines shared by everyone, there will be only one network. The maximum bandwidth across the network is 1 Mbps, which all individuals share. This means that the public network connection to the Internet need only be a 1 Mbps pipe.

However, in a hotel or residential MTU with individual connections, 1 Mbps should be delivered to each unit, rather than to the building as a whole. In an eight-unit complex, an 8 Mbps Internet connection would be optimal. For a 20-unit complex, a 20 Mbps connection is required if the goal is to have all units achieve maximum phoneline bandwidth while all units are under maximum use. In other words, bandwidth scales directly with the number of units.

Clearly, most MDUs will need a high-bandwidth connection. Cable Internet connectivity should be considered in such situations. Theoretically, cable's bandwidth tops out at 27 Mbps or even higher, under certain configurations. In practice, even under heavy network conditions, overall cable bandwidth rarely-if ever -drops below 8 Mbps.

In an MDU or MTU environment where individual tenants have separate phone systems, the ideal solution then becomes a phoneline network hooked to a cable Internet system via a broadband gateway that distributes the data bandwidth and keeps individual network branches independent and secure. How does this work in real life?

Setting Up
When deploying Internet access to a commercial building in South Dakota, Black Hills FiberCom decided to use the building's telephony network. "We could have run coax, but it was just too long a run," recalls John Hamilton of BHF. "In fact, to run anything would have been difficult, because of the building's construction-we couldn't even run Cat 5 because of the construction."

Instead, BHF turned to the network that had already been laid: the telephone wiring. "Once again, [phoneline networking] bailed us out," Hamilton recounts.

They determined to set up access in the building's equipment room and, from there, distribute it to all units over a phoneline network. Given the situation, BHF decided to use a cable Internet connection as the inbound data pipe. Next they needed to connect the broadband network to their internal phoneline network.

After reviewing their options, BHF decided to use the Com21 DOXport 8080 multi-dwelling unit cable modem system. "It was the only hard-wired solution that we had for those applications," says Hamilton. "It was the product we found that actually filled that particular need."

The only comparable solutions involved wireless networks, but that would have brought up a host of new issues. "That's always a problem with masonry and steel construction," Hamilton notes. "If we were going to use hardline wire, the DOXport 8080 was about all we had....it's a unique product.

The result? "We're happy with it," Hamilton says. "It's been real steady....it's been working quite well for us." Hamilton believes BHF nearly achieved the ideal goal of 1 Mbps of consistent bandwidth to each unit. "We're getting pretty darn close to that," he states.

Conclusion
An optimal solution for MDU or MTU units with individual phone lines is a three-part system: a phoneline network connected to cable Internet through a broadband gateway device that links the two together and secures individual units' data.

High-speed Internet access is no longer optional. In today's fast-paced, 24/7 world, the Internet has become nearly as ubiquitous as the telephone, and low-bandwidth solutions won't be sufficient for long. Luckily, in buildings where infrastructure rollouts are difficult or impractical, phoneline networking can easily bring high-speed access into existing multiple-unit buildings. Maximize bandwidth to each unit now, and broadband will become a much longer-term solution.

About the Author
Ehsan Rashid is Vice President and General Manager, Access Products Division with Com21. He may be reched with questions or comments via email at erashid@com21.com