Controlling the flow

Telecommunications carriers are bringing their wide-area networking offerings together on unified network backbones using Internet Protocol (IP). Customers will still have access to existing services such as Frame Relay and Asynchronous Transfer Mode (ATM), but they are being offered new and better

virtual private networking (VPN) options and the use of Ethernet will continue to grow.

All of Canada’s major carriers are moving toward unified IP-based networks, says Iain Grant, managing director of Montreal-based consulting firm SeaBoard Group. Telus Corp. moved first with its IP One initiative. Bell Canada followed shortly after and MTS Communications Inc. acquired a new IP network last year by buying Allstream Inc., which has had an all-IP network for about five years. “”Follow the money,”” Grant observes. “”Not only is it cheaper to build and cheaper to operate, but it’s more fault-tolerant.””

Kevin Mitchell, directing analyst for service provider voice and data at San Jose, Calif.-based Infonetics Research Inc., says three things are driving carriers toward IP networks: broadband Internet services, IP-based virtual private networks (VPNs) and voice over IP.

What’s making these all-IP networks possible, Grant says, is Multi-Protocol Label Switching (MPLS). Designed to improve the transport of data packets through IP networks, MPLS has emerged as an important tool in making those networks more secure and more reliable. A late-2004 Infonetics survey of service providers found 81 per cent already use MPLS. Infonetics predicts that figure will rise to 92 per cent by the end of this year.

MPLS tells the packet how to get to its destination

Andrew Malis, chairman and president of the MPLS and Frame Relay Alliance and chief technologist at Naperville, Ill.-based equipment manufacturer Tellabs Inc., says MPLS was originally meant to be a tool for traffic engineering. But it has now been recognized as a good way to build VPNs and prioritize traffic on IP nets.

“”People started seeing that MPLS is actually a pretty nice tool set to enable a whole raft of applications as well,”” Malis says.

As the name implies, MPLS works by attaching labels to packets to control the route they take through the network. Where IP itself specifies a packet’s destination and leaves it up to routers throughout the network to pass the packet in the right direction, MPLS makes it possible to specify what route packets should take. Doing this, Malix explains, allows you to create a traffic tunnel through the IP network — similar to virtual private networking. And by providing more control of the routes that packets take, MPLS also helps ensure quality of service — important for some applications, especially voice over IP.

Like Synchronous Optical Networks (SONET), Malis adds, MPLS is designed to re-route traffic and restore connections within 50 microseconds if a link fails.

Traditional circuit-switched networks were expensive, Grant says, but they were reliable. On its own, IP could not guarantee the sort of reliability telecom carriers knew their customers had come to expect. MPLS has given the carriers a way of assuring customers of carrier-grade reliability over an IP network. As a result, Grant and other analysts say, the future of telecommunications looks to be unified voice and data networks based on IP and MPLS.

That doesn’t necessarily mean many organizations will be buying MPLS services as such. The major carriers do offer services specifically identified as MPLS, but the technology can also serve as a transport for other services, including Ethernet, ATM, Frame Relay and VoIP.

Malis says customers will continue using older technologies such as ATM and Frame Relay. “”One thing service providers have found is that once you deploy a service, it’s pretty hard to take it back,”” he says. “”There’s still a lot of X.25 out in the world.””

He says many firms still use Systems Network Architecture (SNA), an IBM communications protocol popular in the 1980s. But carriers can run older services over an MPLS transport, eliminating the need to maintain separate network backbones, and that is the way most carriers are moving, Malis says.

“”IP by itself is a great technology for IP,”” says Lindsay Newell, vice-president of marketing in the IP division of Paris-based Compagnie Financiere Alcatel, which provides carriers with a platform for offering Ethernet services over an MPLS backbone. “”MPLS is what enables you to add Ethernet services, Frame Relay services, ATM services, all on to that network.””

Ron McKenzie, executive vice-president of marketing and business development at Allstream, says that while MPLS has been around for a few years and some customers had adopted it to future-proof their networks, now the benefits are becoming apparent. Convergence of voice and data is a big driver for MPLS today, he says, and in future the ability to prioritize application traffic will capture enterprises’ attention. In recent months, Allstream has signed customers such as Scotiabank and Great-West Life for its MPLS-based services.

“”Our IP MPLS network is really our backbone of the future,”” says Jeremy Wubs, director of enterprise marketing for IP data and managed networks at Bell Canada, which is consolidating its networks and pushing more and more traffic onto MPLS, he says.

Bell offers an MPLS service providing multiple classes of service for different types of traffic, such as a standard level for e-mail and general data applications and a high-priority level for VoIP traffic. Wubs says the service appeals mainly to large enterprise customers but Bell expects it will start to become more popular among small and mid-sized organizations.

Quality of service is a key selling point, Wubs says, adding Bell can create complete virtual private networks and even segment these into sub-VPNs if the customer wishes. “”That has the added benefit of being able to keep a department secure.””

Ethernet more popular in wide-area networks

VPNs are widely used for remote access to corporate computer systems and for secure IP communications among sites, because they create secure “”tunnels”” through the public Internet. But with traditional VPN technology, each pair of points requires a separate VPN tunnel. That means that if an organization wants to connect multiple locations, it usually uses a hub-and-spoke topology, says Newell. Say the hub is in Toronto. Traffic from Vancouver to Calgary would then have to travel through Toronto. But an MPLS VPN is multi-point rather than point-to-point, so traffic can go directly from any point to any other.

Atomic Energy of Canada Ltd. uses Bell Canada’s IP Virtual Private Network service to link major Ontario sites in Chalk River and Mississauga, with smaller facilities in Ottawa and Montreal. The service replaced separate T1 lines that supported voice and data using Nortel Networks Corp. Passport products. Bob Graham, an AECL network supervisor and technical lead for the migration, said switching to the VPN service eliminated maintenance cost for the Passports, increased bandwidth and allowed AECL to assign voice traffic to a near-real-time service level. The service has reduced costs by about 20 per cent, he says.

“”Almost everyone who has deployed MPLS for traffic engineering is now deploying VPN services,”” Malis says.

Perhaps more visible to many business customers than the MPLS technology pervading carriers’ networks is the growing availability of Ethernet services in the wide area. Metropolitan Ethernet services, which extend the long-established LAN technology to link multiple locations in a city, have become popular in the last couple of years. Utility telecom companies are using their city-wide fibre networks to offer customers the option of extending their Ethernet LANs to make multiple offices look like a single logical network.

Ethernet appeals to business customers largely because of its familiarity, Newell says. “”It’s their LAN,”” he says. “”It’s a simple technology. It’s ubiquitous.””

Enabling virtual private lan services

Grant, however, is not sure how far Ethernet’s growth will go. Utility telecom companies are already offering metro-wide Ethernet services, and Ethernet between cities will come, he says, but for more critical traffic Ethernet may not be best. Ethernet’s reliance on collision detection and retransmitting lost packets makes more sense in a local network than in the wide area, he says. “”The chaos of the local network doesn’t make sense to replicate on the wide-area network.””

But Newell says carriers can offer Ethernet services over a wide-area MPLS backbone because MPLS gives carriers a good way of separating different customers’ traffic and helps the LAN technology scale beyond metropolitan areas to longer-haul links. “”To really make Ethernet successful,”” argues Newell, “”(carriers) need to scale it the same way that Frame Relay has. On a pure Ethernet switched network you can’t do that.”” Alcatel uses MPLS to encapsulate Ethernet packets for transmission over longer distances.

MPLS is the basis for Virtual Private LAN Service (VPLS), which provides customers with an Ethernet interface to an underlying MPLS backbone. Paths through the network created with MPLS labels, called pseudo-wires, look to customers like separate circuits. VPLS can create multipoint networks efficiently, Newell says, whereas doing the same thing with another technology such as Frame Relay or ATM would mean setting up a series of permanent virtual circuits.

“”With VPLS there is no difference between five customer offices in a metro and five customer offices in five different continents,”” says Newell. Making distance irrelevant is, after all, part of the promise of unified IP networks.

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Grant Buckler
Grant Buckler
Freelance journalist specializing in information technology, telecommunications, energy & clean tech. Theatre-lover & trainee hobby farmer.

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