MPLS: Convergence's Class Act
The right managed MPLS service gives businesses the quality, scalability and security needed to support exceptional IP telephony network performance. But buyers beware: All services are not created equal.

Believe the hype: MPLS has finally arrived. Seventeen percent of enterprises finished an MPLS implementation in 2005, and another 17 percent will wrap one up by the end of this year, according to Forrester Research. What is driving this action after so many years of talk is widespread carrier MPLS adoption. Service providers like AT&T are building their managed service portfolios around the promise of multiservice networks delivered via MPLS.

As carriers adopt MPLS in their core networks, enterprise businesses are getting access to the quality of service, scalability and the tight protection that multi-protocol label switching (MPLS) has long promised. For businesses deploying multi-site IP telephony networks, MPLS is the WAN technology of choice for cost-effective and secure integrated voice and data service. Businesses can use MPLS to prioritize their WAN traffic end-to-end to ensure they get the level of performance demanded by time-sensitive voice and other business-critical applications.

MPLS has a particular appeal for companies that are moving to convergence but want to keep expenses down while ensuring the best network performance possible. Not only does an MPLS-based WAN promise the kinds of quality of service capabilities that voice applications require to avoid lost packets, distortion and dropped calls, but MPLS also scales easily to support growing businesses.

Traditional private line and frame relay WANs use a hub-and-spoke architecture. But because MPLS uses a peer-to-peer networking architecture, each location can communicate to all other branch offices through just one connection to the WAN cloud. That keeps capital equipment costs to a minimum. MPLS also delivers a high level of security to protect both voice and data applications.

Priority Order
Part of the beauty of MPLS is that it removes much of the complexity that is associated with traditional telecom network services. Now, instead of needing a private line or frame relay network to handle mission-critical applications like supply chain management or customer resource management (CRM) and a separate network for voice, businesses can use a common managed carrier service using the same network to transmit all their traffic across the WAN, says Rick Stein, Executive Director of Business Voice over IP Product Management for AT&T.

Stein says the customer can use one common network and just assign different classes of services to different applications based on priority. For example, voice applications would be assigned Class of Service 1 for real-time delivery. Video, enterprise resource planning (ERP) or other mission-critical applications that require near real-time could be assigned to Class of Service 2. And e-mail and Internet traffic would be assigned a lower priority.

To signal to WAN devices what class of service a particular application should receive on the WAN, Label Edge Routers (LERs) issue an identifier that includes information from the routing table entry, such as destination address, bandwidth, and source address. The identifiers – or labels – are instrumental in maintaining security by hiding the actual IP addresses and other information about the packet stream. While this makes security comparable to the protection provided by frame relay or ATM, MPLS doesn't guard the packet contents within the packets.

Many Happy Returns
So how can an effectively managed MPLS-based VoIP service benefit a business' bottom line and help improve corporate-wide productivity? At the most basic level, consolidating applications onto a single network saves companies the cost of capital equipment, management expenses, and bandwidth. But that isn't the only cost benefit that comes as a byproduct of consolidating traffic that otherwise might have to run across multiple networks onto a single infrastructure.

In managed VoIP services such as AT&T's, edge devices rely on compression technology that fit more high priority voice packets onto the network than a frame relay or private line network, thus saving bandwidth without sacrificing quality. MPLS also helps companies tap all the cutting-edge IP telephony features that have such a broad appeal to businesses that are looking to convergence to improve their corporate productivity.

The benefits of MPLS are many. Stein points out that AT&T's VoIP service supports things like number portability and "Find Me." This helps one employee locate another fast and with minimal hassle.

"With new technologies coming, employees have the ability to go into a phone directory and see not only the names and numbers in that directory," says Stein, "They can also see where that person is and to which device he or she is currently connected. They can click on that person or number in the directory and connect to him."

At Your Service
MPLS promises a host of benefits to companies making the move to VoIP, but businesses should proceed with caution when it comes to selecting a carrier. So what should a business look for in an MPLS-based managed service to support its move to convergence—and what should it avoid?

Reputation and expertise certainly count, but when it comes to choosing an MPLS-based managed WAN, businesses should focus on the carrier's network itself. Does the network have sufficient bandwidth to support its customers' capacity requirements? Is the network limited in its geographic reach or is flexible enough to cover a company's local, national, and global communications needs? And has the carrier cut any corners when it comes to the way their network is architected?

AT&T's Stein points out that not every carrier employs MPLS throughout the core of the network, and many implement MPLS at the endpoints only. The result is less than stellar performance that doesn't live up to MPLS' promise.

"Unless the carrier uses MPLS throughout the network, there is a risk of bottlenecks and other issues that could derail network services and impede operations—or worse," says Stein.

Companies need to be aware of how the managed service provider handles voice engineering and traffic shaping. Does the carrier oversubscribe its network and hope for the best? Of course, this approach won't cut it when it comes to keeping voice traffic flowing because a delay can diminish voice quality or even worse.

Thus it is critical that companies select an MPLS-based managed service that provides the kind of guaranteed quality of service throughout the network they need to maintain exceptional voice and data performance. Luckily, companies have more options to choose from than ever before that by supporting the best performing converged network will help them become more efficient and productive businesses.