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VOIP hot, but users sweat
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April 08, 2002 (Computerworld) -- Voice over IP is one of the hottest technologies around, but users caution that anyone attempting a VOIP project needs a lot of bandwidth and an equal amount of patience.
IT managers involved in VOIP efforts said they face a daunting task: making sure that voice packets, which must be given priority on networks for reasons of sound quality, don't gum up their data feeds.
"You've got to beef up the one network that's going to handle both voice and data," said Mark Katsourous, communication automation specialist at the University of Maryland in College Park. "We're talking a major forklift upgrade."
The university has installed VOIP phones made by Basking Ridge, N.J.-based Avaya Inc. in some of its dormitories and remote locations. But to do a wider rollout, Katsourous said, he would first need to install new routers that could guarantee voice quality and backup power for the voice devices.
"There is no such thing as a quick voice over IP implementation," said Zeus Kerravala, an analyst at The Yankee Group in Boston. He said one of the chief limiting factors is that a wide-area network using a T3 carrier line "is only one-half the speed of a typical LAN," which is the bandwidth VOIP requires.
St. Michael's Hospital in Toronto recently boosted bandwidth from 3M to 40M bit/sec. on its LAN and 20M bit/sec. on its WAN. "I wouldn't have entertained voice over IP on our previous network," said CIO John Wegener.
Like other users, St. Michael's is using a VOIP/private branch exchange (PBX) convergence tool as it transitions to Internet telephony. Wegener stressed the importance of getting VOIP, telecommunications and network vendors on the same page before starting a major project.
"You really need all three of them around the table if you want to get things resolved," he said. "You need to lay out who's responsible for what from the start, because it never goes 100% smooth."
More customers will likely be calling those powwows in coming years, according to Kerravala. He said that while over-all demand for phone systems likely will be down slightly this year, Yankee Group expects VOIP's share of the market for new installations to rise from 10% in 2001 to 25%.
The city of Houston last month began work on what it says will be the largest VOIP deployment by any government body in the U.S. to date, linking 25,000 phones in a $15.7 million, 18-month project.
Denny Piper, the city's CIO, admitted that it won't be easy. "We're going to find some holes in our network, but we would have had those anyway," he said. "That you might run into problems is not justification for not doing it."
Houston's municipal government currently operates 47 PBX phone systems and 43 separate voice-mail systems. It has spent the past five years installing a Cisco Systems Inc. network and will also use Cisco as its VOIP vendor.
But even with a single vendor, there are costly redundancy and quality-of-service issues, Piper said. "We're looking at another $2.2 million in incremental network upgrades over the next year," he added.
Steve Leaden, president of telecommunications and networking consulting firm Leaden Associates Inc. in Washingtonville, N.Y., said he believes that protracted VOIP implementations will prove a major challenge for IT executives.
"Every IT department I talk to that's doing this, these guys are on total overwhelm," Leaden said.
Network Needs
Users considering VOIP installations should check these items to make sure their networks are ready for the technology:
Measure and characterize end-to-end delays and packet loss for IP telephony across your network.
Companies with slower networks or nets running near capacity, make sure wiring closets recognize the 802.1P protocol for traffic prioritization at Layer 2.
Your core data network must be able to prioritize packets at Layer 3.
Determine WAN use, preferably no more than 85% at peak traffic times.
Identify your low-speed links (under 256K); these may degrade voice quality.
Probe for network trouble spots (dropped packets, queue exhaustion, ingress/egress interference, CPU use).
Determine whether you need to add redundant power supplies to ensure reliability.
Source: Nortel Networks ltd., brampton, ontario
Related stories:
- Users seek more rigorous monitoring with VOIP networks, April 8, 2002
- Net2Phone, ADIR sue Cisco over VOIP technology, March 20, 2002
- Lego Is Moving Toward VOIP, but Technical Issues Remain, Jan. 21, 2002
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