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Of VoIP and Bandwidth

The difference between success and failure in this world will be decided by the network infrastructure that is installed.


November 1, 2004  


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Voice over Internet Protocol (VoIP) is finally realizing its true potential, but what seems lost in all the furore is the impact the tech- nology will have on network infrastruct- ures being built today.

What is abundantly clear is that the network must provide enough bandwidth to accommodate both the existing data requirements and the added traffic associated with voice.

Further, the bandwidth must be sufficient to handle this added voice traffic without any “hiccups.”

Since voice information does not tolerate breaks in timing in ways that data might, the traffic must move consistently and seamlessly at all times.

Surprisingly, it appears not to be that way at all.

Cable plant support

How else can you explain the fact that that many early adopters — upwards of 40%, according to one estimate — were disappointed with their VoIP implementation? It turns out that the network infrastructure was not built to sustain the added traffic.

Assuming that the networking gear will operate at higher rates, does the existing cable plant and will the new cable plant support the requirements?

We are at a point where the cost difference between Category 5E and Category 6 makes it difficult to argue against a Category 6 requirement for new installations.

Yet, when addressing existing instal-lations, the lack of wholesale network cabling upgrades to Category 6 in the market today indicate that technology is simply not driving such a requirement.

In terms of the Layer 1 infrastructure, what does all this change mean? We have built a strong foundation of “legacy” standards, but will they continue to be relevant?

The underlying premise of much of this is the separation of voice and data, but do we not need to re-examine our conclusions when the facts change?

We can now address both voice and data applications with a single cable, with all existing relevant standards mandating a minimum of two connections.

Is a one cable implementation acceptable? At least one client of mine recently installed a new structured cabling system with the knowledge that voice over IP was the technology that would be implemented.

Prior to going live, a decision on whether one cable could suffice to serve both data and voice requirements had to be made.

With lingering uncertainties about the success of the VoIP implementation, the safe course was to install a standards-based two cable system.

In hindsight, a single cable per work-station would have worked just fine.

Standards for pathways and spaces are based on multiple cable implementations. Telecommunications closets are sized for equipment and cable plants dedicated to the separate voice and data systems.

In the short term, nothing should change with these, particularly in view of the difficulties often faced in procuring the minimum standards.

Over the long term, we may see changes in these requirements, if only that the minimal allowances made today become truly adequate in the future.

Design changes are being implemented in today’s infrastructures. A practice becoming quite regular is the installation of data grade UTP for voice, with the closet terminations on patch panels.

Voice connectivity is achieved via pigtails routed from the patch panels to the voice backboard where they are cross connected in traditional fashion.

The benefit is that future VoIP can be achieved by removing the pigtails and patching directly to the data gear that provides VoIP services.

Backbone considerations may also change from a service entry perspective. It is customary to provision multiple cop- per pairs from the service entry to the customer’s equipment closet to accom-modate voice and data circuits from the service provider.

Future requirements may warrant fiber optic backbone to support end to end IP connectivity.

While backbone cabling is typically considered application-dependant and changeable with changing needs, it is often cost effective to provision additional cable facilities in conjunction with today’s requirements.

As sophisticated as VoIP implemen-tations have already become, it is still early in the game.

Over the coming years, many changes will occur to infrastructures that support the technology, which is why the time is right to start preparing for them in a sound and comprehensive manner.

Rob Stevenson, RCDD/NTS Specialist, is Communications Division Manager at Guild Electric Ltd. in Toronto, and a member of CNS Magazine’s Editorial Advisory Board.