ITPRC NEWS - July 2001
Getting to VoIP - It’s the
By Irwin Lazar
As I write this I’m returning on a plane from The Burton Group’s (http://www.tbg.com) “Catalyst USA” conference in San Diego, California. The theme of this year’s conference was “i-before-e”, or “Infrastructure before E-Business.” Nowhere is this theme more important than for those organizations that are considering converging their voice and data networks into a single infrastructure, based on IP.
Convergence offers enterprises significant opportunities to reduce complexity, enable new services, and increase network flexibility. However, convergence requires carefully examining the enterprise network infrastructure to insure that it is up to the task of meeting the stringent quality and reliability demanded by voice communications.
Vendors are currently hyping Voice over IP to the desktop as a way to open up the closed, proprietary nature of the PBX to a world of new applications. By separating out call control, call management, and telephony, as well as by treating the desktop IP phone as a computer, application developers can write new applications to improve productivity. Examples include unified messaging and call center support applications. Enterprises can also simplify moves, adds and changes by using the self-registering capability of many IP phones.
However, Voice over IP comes with a cost, improved network infrastructure. One speaker at Catalyst noted that the migration to Voice over IP was a lot like walking to the bathroom in the middle of the night. You know where you want to go, but you often stumble over things you can’t see. The ability of the network to properly support Voice over IP is dependent on the ability to provide quality of service and resiliency.
Quality of Service:
To properly support VoIP the network must be able to provide guaranteed levels of performance that insure that voice packets arrive in sufficient time to avoid noticeable delay to the end users (generally less that 150 milliseconds). Jitter (the variance in delay) must be minimized to avoid hiccups in normal conversation. The network must also protect against dropped voice packets in time of network congestion.
In times of network failure individuals many individuals can still work if they can use their phone. However, if the phone is part of the network, phones will fail when the network fails. This generally means that a converged network must now be treated as a mission critical entity, in which outages are no longer acceptable. This is a tremendous shift in paradigm for network managers.
Given the requirement for QoS and resiliency, network managers must evaluate their network architectures to insure the ability to support VoIP. This means assessing the QoS capabilities of key components such as routers and switches. It also means designing the network to minimize the impact of failure. This is easier said that done. For example, many current networks utilize Cisco 5000 series switches in their wiring closets for desktop access. These switches cannot support multiple output queues, so they are unable to provide QoS for specific classes of applications. This means that VoIP may require a large upgrade of network hardware.
Network managers must also have the tools to manage their networks in such a way that they can monitor end-to-end application performance. When someone reports to the help desk that their calls are filled with static, simply responding that “the network is up” is insufficient. “Net” heads must quickly learn to become “bell” heads to support voice applications on their networks.
VoIP offers tremendous opportunities, but those opportunities aren’t without cost. Those organizations that invest in infrastructure before VoIP migration will be those that are best poised for success.
Irwin Lazar is a Senior Consultant for The Burton Group. He focuses on
strategic planning and network architecture for Fortune 500 enterprises
as well as large service providers. He is the conference director for
MPLScon and runs The MPLS Resource Center www.mplsrc.com and The
Information Technology Professional's Resource Center www.mplsrc.com.
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