Consider Managed Network Service Providers "WAN" Thinking About Convergence

BY MIKE BERTA

If you are not piloting a converged network, then you are behind the times. Today, telcos are making it easier to converge voice and data on a single backbone with several Wide Area Network (WAN) transport choices, including frame relay, Asynchronous Transfer Mode (ATM), and the new and improved IP-enabled network that promises to lower prices and simplify configurations. Each of these transports have pros and cons, therefore a WAN that supports convergence may need a mix and match of all the above to create the best solution at the right price. The challenge is not only what and how much to do, but also, to satisfy the different views of each person in the organization.

The CIO's network view is challenged with managing all of the network services and products so that the end user has always-on connectivity. The CEO is determining the true network ROI in terms of productivity and profitability. As each see the potential of the WAN to benefit the communication of end users, the real question facing decision makers is which solutions to implement that can cost effectively meet everyone's goals.

This article discusses the impact of converging voice and data communication over different WAN technologies, citing some of the challenges of managing this convergence and introducing the option of outsourcing this management.

Converging Communication
As businesses grow, operational expenditures increase to support the need for more bandwidth. However, capital expenditure budgets for new equipment are currently on a decline, forcing businesses to maximize the value of existing investments by consolidating communications over data-centric networks. Converging voice on data networks increases the value of the inherent WAN investment because of the greater utilization of these resources. Now that converging voice and data can benefit the bottom line, it is important to know which technology offering will work best.

Currently, most companies use two unique networks to handle voice and data communication. The voice network used to be a VPN (voice) that the long-distance carriers offered at a set price, e.g. seven cents a minute. The data network was a connection of routers that allowed traffic to flow from remote locations to the home office.

Converging voice and data over the WAN can improve the performance of operational spending and maximize capital investments in networking gear. Adding voice to data running over the WAN affords businesses transparent communication, so remote locations (regional and district offices) and telecommuters have the appearance of being under the same roof as their colleagues back at the home office. Providing employees with anywhere, anytime access becomes a competitive business advantage and increases productivity.

As with any convergence or merger of technologies, there are some challenges that need to be overcome in order for a converged network to operate productively. Voice and data have long run on separate networks because of their unique characteristics. Voice networks operate in real time, with its users expecting a particular set of behaviors from the network (dial tone, smooth speech, etc.). Voice is sensitive to delays (latency) and jitter, though it can withstand a small loss of information as long as real-time interactive behavior remains consistent. Whereas data networks are not sensitive to delays or jitter, they cannot tolerate losing information.

In order for a converged voice/data network to meet the desired performance levels to provide a business advantage, the network must be well managed, giving voice packets priority over data packets. Because of the differences between voice and data, managers of networks must first tag voice packets with a Class of Service (CoS) mechanism (RSVP, DiffServ/ToS, port prioritization, etc.). Voice packets can also be compressed to allow for, in some instances, no increase in bandwidth to a remote site. This compression should be selected to ensure quality and bandwidth utilization.

Next, managers must employ Quality of Service (QoS) techniques that set preferences through queuing mechanisms in routers and switches. Then, before the information leaves the LAN, they must use link fragment and segmentation or similar techniques to shorten the size of packets to minimize delay across WAN links.

Today's WAN Technologies
The most commonly deployed WAN architectures are frame relay, ATM, and Ethernet.

Frame Relay
Frame relay is a connection-oriented service employing Private Virtual Circuits (PVC) similar to packet switching X.25. Frames can vary in size and bandwidth is allocated on demand. Multiple virtual sessions are generated on a single interface that provides direct connections to remote locations in a secure fashion. Frame relay has been a major telco offering for most of the 90's, and will continue to be an offering through this decade. By monitoring the traffic flows and adjusting the Committed Information Rate (CIR) or bandwidth as needed, frame relay can and does carry voice with few to no quality issues.

Asynchronous Transfer Mode (ATM)
Like frame relay, ATM is a connection-oriented technology that organizes information into 53-byte cell units for transmission. Because of this fixed length, network performance can be more predictable. These cells are structured with a header (5 bytes) and a payload (48 bytes).

When information flows through an ATM network, the packets, bytes, or frames are segmented into the smaller cells. This queuing allows ATM's QoS capabilities to adhere to traffic policing policies so that critical information has priority. Additionally, the smaller, consistent cell size -- compared to variable frames -- uses less processing overhead, improving the performance of the network. Even with the advantages of ATM, the offering is only at T1 (1.544 Mbps) and T3 (45 Mbps) speeds. Today, most companies have a communications need of a fractional T1 for remote locations and ATM at the host site. ATM's fixed cell structure could have issues with VoIP compression standards if not designed correctly.

Ethernet
Ethernet is one of the most widely deployed connectivity solutions in the local area. Ethernet is based on a bus topology where end points (PCs, phones, printers, etc.) compete for access to the network. The end point "listens" to determine if the network is free of traffic before transmitting the frames of information. If by chance the network is not idle, then there is a "collision," which jams the network. After a random pause, the end points try again.

This network is high bandwidth and in the Gigabit range today. With the high bandwidth that an Ethernet network offers, one would think that little is needed for traffic to pass between point A and B -- unless point B is across the country and a WAN is between. Typically, Ethernet traffic is in your building and it crosses to a frame relay, ATM, or VPN service to get to remote locations. So when adding voice to such a segmented, routed, converged, and unlimited end user point network, management tends to be unwieldy and information can get misplaced.

Outsourcing Network Management
Monitoring and managing the performance of a converged network can be a daunting task, and often consumes the IT department's resources with daily "fire drills" trying to resolve issues with carriers or a problem experienced by a user. The combination of smaller budgets and decreasing staff is driving businesses to increasingly explore managed network outsourcing, a market that industry analysts at Yankee Group predict will increase to $7.4 billion by 2004.

Partnering with a managed network service provider (MNSP) is a viable option for IT departments; they allow the service provider to manage the network so the IT department can implement the technologies that can help manage the business. These MNSPs provide supplemental support to IT departments by offloading tactical processes. This is an important differentiator because outsourced services such as maintaining contracts and service level agreements with carriers can free up internal resources to complete more strategic projects for the business.

Conclusion
With so many technologies traversing the network today, businesses are looking to standardize business communication processes -- phone calls, e-mail, videoconferencing, etc. -- while controlling costs and preserving the integrity of critical business information. Technological advancements can have a profound effect in the way we communicate, requiring the ideal network architecture to support a mix of technologies and up-and-coming standards.

Supporting convergence is not an option, as the end user will come to expect a certain standard of connectivity and service. To alleviate associated network management challenges, IT managers are turning to MNSPs for proactive network management, a partnership that optimizes resources and boosts productivity -- satisfying the needs of the entire organization.

Mike Berta is director network consultants for Vanguard Managed Solutions. VanguardMS is a leading source of managed network solutions. Leveraging its leadership and expertise in voice, video, and data over a broad range of multi-service technologies, VanguardMS helps organizations get the maximum value from their IT infrastructure through fully customized, industry-specific, end-to-end solutions that support their businesses networking needs.