Looking Under the Hood�Part II: The Switching System in Context
In our last tutorial on IP switching system evaluation, we considered the importance of evaluating the prospective vendors, their background and target market, and the demeanor of their representatives, prior to undertaking a search for the best switching solution to meet your organizations requirements.
If you've already done this, you have likely eliminated a number of firms. For example, perhaps some vendors were in the wrong market for your solution (they are in the carrier market, and you need an enterprise solution); other vendors primarily catered to large, multi-location enterprises (and you only needed a system for your small business); a few vendors were headquartered in another part of the world (and you wanted to do business closer to home); a handful of the vendors did not have expertise in a technology that you needed (such as in-building wireless handsets); or you ended up with an obnoxious or unresponsive company representative, which took them off your list based on principle.
Assuming that your initial list of potential vendors has now been whittled down to a more manageable size, lets now examine how that switching system must operate within the context of your larger network and consider some evaluation tips in this area.
- What is driving this new purchaseexpansion or obsolescence? Let's suppose that your business is doing well, and as a result, you are expanding into a new city. If this is the case, then your best bet may be to just buy another system like the ones that you already have in place, install it at the new location, and move onto other challenges. Several major problems, including multi-vendor interoperability challenges, carrier connections, and vendor contracts, can be resolved rather quickly with such a simplified approach.
On the other hand, if your current communication system is no longer meeting your needsbecause it has hit its maximum expansion capability, you can no longer easily obtain replacement parts, the original vendor has gone out of business, your leased-line contracts are up for renewal and it now makes sense to move to a VoIP infrastructure, or some similar reasonthen you have a very different challenge on your hands. So be sure to give serious consideration to the question Why are we replacing our existing system?, so the goal that you are shooting for is very clear.
- Do you plan to migrate your network to a softswitch architecture based upon the IP Multimedia Subsystem? In general, IMS deployments today are found primarily in the networks of telecom providers that are looking to integrate both fixed and mobile multimedia services. However, very large enterprises (many thousands of end users) take on many of the characteristics of a telcoa fact that the bigger vendors in this market have recognized long ago. Accordingly, they may be inclined to steer big enterprise customers toward an IMS solution instead of an IP-PBX solution. The phrase long term vision comes to mind here, as you must come to grips with how long the system in question is expected to last, and how it is to fit with communications requirements that may be further out on the planning horizon.
- With what other programs and/or processes must this new communications system integrate? One of the interesting capabilities touted by many of the small- to medium-sized IP-PBXs that we studied was their ability to integrate with email programs, such as Microsofts Outlook, or contact databases, such as Sage Softwares ACT! Is an integration of this sort also a requirement for your network? And if you take a step back to look at the bigger picture, is this new communication element really part of a larger system such as a call center? What about support for road warriors? Do you need a unified messaging solution that can integrate voicemail and e-mail systems? The ability to integrate with other systems can be a key product differentiator and should be high on the list of requirements.
- What protocols and standards must be supported? In almost every case that we examined, looking at both softswitches and IP-PBXs, support for the Session Initiation Protocol (SIP) was included. However, your network may have requirements for other protocols and standards, such as the Media Gateway Control Protocol (MGCP), for communication with media gateways; the H.323 protocol, which is often used with video conferencing systems; or the Inter-Asterisk Exchange (IAX) protocol, which is used for communication between Asterisk servers. Required support for these other protocols and standards may make for an easy way to further trim down the list of potential vendors and systems.
- Is your building infrastructure compatible with a system upgrade? During the course of the vendor and product research, we uncovered switches with form factors that are all over the mapfrom telephone-book-size units, to 19-inch-rack-mounted devices, to systems the size of your refrigerator. Are there any physical-size, ventilation, power, or other physical plant constraints that must be taken into consideration?
Many older switching systems used proprietary wiring connections between the switch and the station sets, which may or may not prove adequate for the new system. How many cable pairs are required in each office? Does the switch support the Power over Ethernet standard, or will you have to install individual power supplies at every telephone? Remember that the cost of the switch or IP-PBX is not the only expense that you will incur, and that any required building revisions must be accounted for as part of the project.
Our next tutorial will conclude our evaluation of VoIP switching products with some guidelines for evaluating the system features, management and support capabilities.
Copyright Acknowledgement: © 2007 DigiNet Corporation ®, All Rights Reserved
Mark A. Miller, P.E. is President of DigiNet Corporation®, a Denver-based consulting engineering firm. He is the author of many books on networking technologies, including Voice over IP Technologies, and Internet Technologies Handbook, both published by John Wiley & Sons.