Frame relay emerged as a cross between the public switched telephone network and point to point dedicated private lines. The idea was to replace the concept of hard wires in "nailed up" circuits with virtual circuits that accomplish the same objective. Circuit switching originated with the telephone companies. It means just what it says. Every time you want a connection, you connect one set of available wires to another until both end locations are hooked together. The circuit stays that way for the length of a phone call or the length of the private line lease. Either way, a dedicated circuit costs you whether you are using it or not.
Virtual circuits are a packet switching idea. Instead of actual wires from point to point, virtual circuits use routers and switches to make sure that information that enters at one port gets to its intended destination without delay or interference. The actual physical paths in the network may be used by many customers during a given time period. However, there is always enough bandwidth in the network to ensure that every virtual circuit acts like it is the only one connected.
The advantage of virtual circuits over physical circuits is the efficiency that comes from greater utilization of the physical paths in the network. These are fiber optic or wireline connections in a metropolitan area or cross-country. The higher the utilization, the lower the cost per user. In other words, you save money using virtual circuits in a private network.
Frame Relay is based on the PVC or Permanent Virtual Circuit. You access the network using a specialized piece of customer premises equipment called a FRAD or Frame Relay Access Device. Within the network frame routers are configured by the network operator to create your PVCs from a list of sources and destinations and your desired bandwidth or Committed Information Rate (CIR).
MPLS or Multi Protocol Label Switching is also a private network arrangement. It's designed to run on the newer IP based networks that are replacing traditional circuit switched or TDM (Time Division Multiplexing) networks. The multi-protocol aspect allows all sorts of traffic to be carried on the network simultaneously. What MPLS layers over the core IP network is a specialized label system. Each label specifies source and destination and quality of service. The labels work something like the virtual circuits of Frame Relay in that they identify where packets are coming from and where they are intended to go. Tag switches also called label switch routers use this information to direct traffic on the network. Like Frame Relay, you use a special device called a ingress or egress router to connect to the MPLS network.
MPLS networks are offered by competitive carriers for transporting voice, data and video from point to point or among multiple locations. The network operator will set up your connections to ensure that you have high enough bandwidth and low enough latency to meet your needs. This level of traffic engineering isn't currently available on public networks, such as the Internet.
Should you stick with your current Frame Relay service or make the move to a MPLS network? Our team of experts can help you compare the options and pick the best one for your applications. You never know. You might just be able to save a bundle of money and get as good or better service as you have now.
