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How Effective Is Frame Relay?

Frame Relay provides a number of benefits over alternative technologies: low overhead combined with high reliability; network scalability, flexibility and disaster recovery; interworking with other new services and applications such as ATM.

Other wide area network switching technologies, such as X.25 packet switching and TDM circuit switching, will remain important where line quality is not as good, when the network itself must guarantee error-free deliver, or when the traffic is intolerant of delay.

Let us now compare Frame Relay with other communication technologies.

Frame Relay Vs Leased Line
Leased line and Frame Relay are two connection technologies normally used to provide permanent, always-on network connections for end user organizations.

With a leased line, a permanent 24 hour per day data connection is established between the user's site and the Internet Service Provider (ISP). This is provided in multiples of 64Kbps (kilo bits per second) with the current normal range of 64K to 2Mbs (million bits per second). The leased line is itself provided by the appropriate telephone company they must have infrastructure or access to infrastructure at both sites. Leased lines are fine if single connections are needed but are inefficient when an organization needs multiple connections because all sites may need leased lines to all other sites.

Frame Relay works on a different principle connections from user sites are made to the Frame Relay "cloud"--and then any connection can be set up within the cloud to other sites. So with the Frame Relay connection there are two connections built in (PVCs or Private Virtual Circuits), with traffic taking the most appropriate route to other sites on the Internet or if one path is not available, taking the other route.

Multiple sites connected by leased lines would mean lots of leased lines, which would be difficult to manage and expensive to both run and alter. With Frame Relay, each site has a connection to the Frame Relay cloud and other connections are "virtual" connections within the cloud. It is completely secure and cost effective.

Frame Relay Vs X.25
The biggest difference between Frame Relay and X.25 is that X.25 guarantees data integrity and network managed flow control at the cost of some network delays. Frame Relay switches packets end to end much faster, but there is no guarantee of data integrity at all. Frame Relay is cost effective, partly due to the fact that the network buffering requirements are carefully optimized. Compared to X.25, with its store and forward mechanism and full error correction, network buffering is minimal. Frame Relay is also much faster than X.25: the frames are switched to their destination with only a few byte time delay, as opposed to several hundred milliseconds delay on X.25.

An evolution beyond the X.25 protocol, Frame Relay is a network interface standard based on statistical multiplexing. By combining the flexibility of X.25 packet protocol with the performance of private lines, Frame Relay Service can move data much more efficiently than the packet protocol. In fact, Frame Relay Service streamlines the processing steps associated with X.25 error detection/correction and routing procedures.

Frame Relay technology takes advantage of highly accurate digital networks with their reduced line errors and intelligent network end point devices with their end-to-end error checking protocols. The reduced per packet processing time allows you to process more user data. Also, the upgrade to Frame Relay Service is simple and cost effective because Frame Relay Service is based on the HDLC protocol, which is popular among LAN bridges, routers and other communications devices.

Frame Relay Vs. Asynchronous Transfer Mode (ATM)
ATM is normally utilized for high bandwidths of 34 Mbps and upwards. There are two ways that corporate networks can afford such bandwidths; in the LAN or campus, or set up their own WAN transmission networks. If corporations have to lease WAN bandwidth to interconnect LANs, Frame Relay is the natural choice. First, at speeds of 2 Mbps and below, Frame Relay is more bandwidth efficient than ATM. Access and switching equipment is more mature, more plentiful and less costly.

Moreover, leased bandwidth can be augmented with bandwidth from public Frame Relay services for maximum cost efficiency. There is little doubt that Frame Relay will be an access protocol to the ATM networks of tomorrow standards are now defining the interface for Frame Relay to ATM internetworking. Investment in Frame Relay internetworking is protected as networking technology evolves.

Mahesh Rathod can be reached at rathodmp@hotmail.com

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