To compete effectively, modern enterprises need to support key applications that enable collaboration and convergence. Physicians, attorneys, engineers, architects, and investment managers alike must be able to collaborate and securely access shared information in real-time. Increasingly, this information (images, case work, software builds, designs, financial trading data, and more) is stored in the form of large files that do not easily move across a traditional wide area network (WAN). At the same time, real-time converged applications such as voice over IP (VoIP) and videoconferencing that require direct connectivity between offices are running over the WAN.Reliance Globalcom Services, Inc., the enterprise business unit of Reliance Globalcom, is the leading provider of managed network and application delivery services for the global enterprise which enhance network connectivity.
Older WAN technologies, such as frame relay, were rolled out in the 1990s to support point-to-point and hub-and-spoke networks that interconnect local area networks (LANs) running less-demanding applications. Frame relay was initially designed to handle LAN traffic that was bursty in nature and is suited to processing frames of different length. Enterprises could effectively support these older applications over T1 (1Mbps) and sub-T1 hub-and-spoke frame relay networks.
Frame relay is not efficient, however, at carrying voice and video traffic. That is, any office must be able to connect directly to any office to minimize network delay, rather than 'hub' through another site. Today's LANs are migrating to 100 Mbps and 1 Gbps to support these more demanding applications. Emerging applications such as VoIP are optimized to run in a multipoint-to-multipoint topology.
As a result of these developments, carriers are limiting their investment in their own frame relay networks, and new technologies have emerged to replace frame relay services. Frame-relay end users are faced with the challenge of migrating away from frame relay to newer network technologies that meet their application needs.
WAN Alternatives to Frame Relay
To address the need for more bandwidth, many enterprises use ATM services to interconnect their larger sites (45 Mbps). ATM was developed to provide higher reliability and more scalability than frame relay networks. Hybrid frame relay/ATM networks are commonplace in medium to large enterprises that need to support five to hundreds of sites. Frame relay is used for smaller sites; ATM is used to interconnect larger sites.
Since frame relay and ATM are connection-oriented technologies, they are configured in a way that mimics private lines. A virtual circuit must be manually configured between each site. A three-site network is relatively easy to configure. But to support any-to-any connectivity for a ten-site network, you would need to configure 45 virtual circuits. To support a 100-site network, you would need to configure 4,950 virtual circuits.
Clearly, neither frame relay nor ATM is suited for today's needs. Enterprises have three WAN alternatives to consider in migrating away from frame relay:
IP VPNs
Configure IPSec tunnels over a public or private Internet connection to build a secure and encrypted network. Pros: low cost, ubiquitous coverage. Cons: IP best effort, only support point-to-point and hub-and-spoke topologies.
IP MPLS Services
Use multiprotocol label switching (MPLS) over a public or private Internet connection. Pros: support any-to-any connectivity with CoS/QoS. Cons: costly transition, complex operation.
Ethernet VPLS Services
Use virtual private LAN service (VPLS) over a carrier Ethernet network to provide a WAN that is configured like a LAN or campus area network (CAN). Pros: simple, support any-to-any connectivity with CoS/QoS; high performance; lowest total cost of ownership.
