Frame Relay

Frame Relay is a virtual – circuit technology that provide low level (Physical and data link layer) service in response to the following demands.

Higher Data Rate at lower Cost-  In the post many organizations used a Wan Technology such as leased line or x.25 to connect single computer.  That data rate was relatively low.  Today, most organization use high speed LAN and want to use WAN to connect this LANs.  One solution to use “T-Line”, but these line provide only point to point connections, no many too many.  Creating a Mash Network out of T-Lines is a very expensive.  For Example – To connect 6 LANS, we need 15 T-Lines.  On the other hand, we need only six-T-Lines to connect the same six LANs to a frame Relay Network.  Frame Relay provides the same type of service at lower cost.

               

            Although the Frame Relay originally was designed o provide a 1.544-Mbps data rate (equivalent to a T-1 Line) today most implementations can handle up to 44.376 Mbps(equivalent to a T-3 Line).

Virtual Circuits-  Frame Relay operates using virtual circuits as opposed to the actual circuits that leased Lines used.  These virtual circuits are what link together the thousand of devices connected o he providers “Cloud” There are two type of virtual circuits permanent and switched.

            Permanent virtual circuits (PVCs) are by far the most common type in use today.  What “permanent” means here is the Telco creates the mapping inside their gear and as long as you pay the bill, they will remain in place.

            Switched virtual circuits (SVCs) are more like a phone call.  The virtual circuit is established when data needs o be tansmitted, then  it’s taken down when the data transfer is complete.