PollyBD Networking Blogspot
Frame Relay
Frame relay could be a service for folks that need associate absolute bare-bones connection-oriented thanks to move bits from A to B at affordable speed and low cost (Smith, 1995). ts existence is due to changes in technology over the past two decades. Twenty years past, communication victimization phonephone lines was slow analog,- and unreliable, and computers were slow and dear. As a result complex protocols were needed to mask errors, and therefore the users computers were too expensive to have them do this work.
The situation has changed radically. Leased telephone lines are now fast, digital, and reliable, and computers square measure quick and cheap. It is suggests the use of simple protocols, with most of the work being done by the user’s computers. rather than by the network. It is this environment that frame relay addresses.
Frame relay will best be thought of as a virtual chartered line. The customer leases a permanent virtual circuit between 2 points and might then send frames
(1.e.. packets) of up to 1600 bytes between them. It is also possible to lease permanent virtual circuits between a given site and multiple other sites, so each frame carries a 10-bit range telling that virtual circuit to use.
The distinction between associate actual chartered line and a virtual chartered line is that with an actual one. the user will send traffic all day long at the most speed with a virtual one. data bursts may be sent at full speed. but the long-term average usage must be below a predetermined level. In return. the carrier charges much less for a virtual line than a physical one in addition to competitory with chartered lines, frame relay-also competes with A.5 permanent virtual circuits, except that it operates at higher speeds. usually 1.5 Mbps, and provides fewer features.
Frame relay provides a nominal service, primarily a way to determine the Start and finish of every frame, and detection of transmission errors. If a bad frame is
Received, the frame relay service simply discards it. It is up to the user to discover that a Frame is missing and take the necessary action to recover.Unique A frame relay does not provide acknowledgements or normal flow control. It does have a bit in the header. however, which one end of a connect on can set to indicate to the other end that problems exist. The use of this bit is up to the users.
