What is frame relay in computer networks

• Frame Relay (frame relay) is a packet-switching technology that is fragmented into transmission units called frames and sent in high-speed bursts through a digital network. Establishes an exclusive connection during the transmission period called a virtual connection.

• It uses a technology called fast packet in which error checking does not occur in any intermediate node of the transmission but is done at the ends. It makes it more efficient than X.25, and a higher process speed is achieved (it can transmit over 2,044 Mbps).

• Another advantage is that you need less powerful switching centers (nodes) and with less memory capacity than those needed by X.25 (each X.25 switching center uses the receive-store-check-relay method, while Frame Relay does not need checking or correcting errors). If the traffic is hefty, with a large number of small packages, its performance is more excellent than X.25. If large files are transferred at high speeds, the price/performance ratio is higher in X.25.

• Frame relay has evolved from X.25 packet switching and the objective is to reduce network delays, protocol overheads, and equipment cost. Error correction is done on an end-to-end basis rather than a link-to-link basis as in X.25 switching. Frame relay can support multiple users over the same line and can establish a 99 permanent virtual circuit or a switched virtual circuit.

• Frame relay is considered to be a protocol, which must be carried over a physical link. While useful for the connection of LANs, the combination of low throughput, delay variation, and frame discard when the link is congested will limit its usefulness to multimedia packet switching was developed when long-distance digital communication showed a large error rate. To reduce the error rate, additional coding bits were introduced in each packet to introduce redundancy to detect and recover errors.

• But in the modem, high-speed telecommunication system, this overhead is unnecessary and infect counterproductive. Frame relay was developed to take advantage of the high data rates and low error rates in the modem communication system. The original packet switching networks were designed with a data rate at the user end of about 64 kbps. However, the frame relay networks are designed to operate efficiently at the user’s data rates up to 2 Mbps. This is possible practically because most of the overhead (additional bits) are stripped off. Frame relay is a virtual circuit-wide area network that was designed in the early 1990s. Frame relay also is meant for a more efficient transmission scheme than the X.25 protocol. Frame Relay is used mostly to route Local Area Network protocols such as IPX or TCP/IP. 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.

Various Key Features of this Protocol are as follows:

The call control packets are used for setting up and clearing virtual circuits. A band signaling is used. Multiplexing of virtual circuits takes place at layer 3. Layers 2 and 3. include flow control and error control.

Characteristics of Frame Relay

Frame Relay service is a service that supports the transport of data Frame relay is connectionless, meaning that each data packet passing through the network contains -address information Frame relay is a service that is provided with a variety of speeds from 56 Kbs up to 25 Mbs. Even though the most used speeds for the service are currently 56 Kbs and 1.544 Mbs. Frames are variable in length and go up to 4,096 bytes Frame Relay is considered to be a Broadband ISDN service One of the unique facts of frame relay service is that the service supports variable size data packs

Features of Frame Relay:

Some important features of frame relay are: Frame relay operates at a high speed (1.544 Mbps to 44.376 Mbps). Frame relay operates only in the physical and data link layers. So it can be easily used on the Internet. It allows the bursty data. It has a large frame size of 9000 bytes. So it can accommodate all local area network frame sizes. Frame relay can only detect errors (at the data link layer). But there is no flow control or error controlThe damaged frame is simply dropped. There is no retransmission. This is to increase the speed. So frame relay needs a reliable medium and protocols having flow and error control.

Frame Format

The frame format used in frame relay. The DLCI length is 10 bits There are two EA locations. The value of the first one is fixed at 0 and the second at 1 is set in the DE (Discard Eligibility) for the part that can be discarded first when congestion occurs. The data size may vary up to 4096 bytes.

Frame Relay Layers A Frame relay has only two layers i.e. physical layer and the data link layer. Physical Layer Frame Relay supports ANSI standards. No specific protocol is defined for the physical layer. The user can use any protocol which is recognized by ANSI. Data Link Layer A simplified version of HDLC is employed by the frame relay at the data link layer. A simpler version is used because flow control and error correction are not needed in frame relay.

The Need for Frame Relay

The frame relay is being used for several reasons. Some of the important reasons are as follows:

1. Higher data rates.

2. It allows the transfer of burst data.

3. It has lower overheads.

Let us discuss these points one by one.

1. Higher Data Rates

It allows the transfer of burst data. If the LANs located at physically distant places are to be connected then there are two options available to do this. Interconnect them using the T lines. Interconnect them using the frame relay. For the direct interconnection, once a T-line is used, we have to pay a fixed charge for it irrespective of its usage because it is a leased line. The T-lines may be fully utilized sometimes and not utilized at all at other times. The frame relay network can handle data rates up to T-3 transmission i.e. 44.376 Mbps.

2. Can Handle Bursty Data

The data being sent from a source to a destination is not of a continuous/constant nature. Instead, it is bursty. That means a large amount of data (data burst) is sent suddenly, and then for some time, there is very little or no data. The T-lines are not equipped to handle such burst data because they offer a constant data rate. The frame relay can tackle this problem. It supports a minimum average data rate and can handle the bursty data.

3. Lower Overheads

In frame. relay network, there are. no acknowledgments sent from the switches back to the sender. There is no intermediate error check. The error checking takes place only at the destination. The intermediate host/switch does not keep a copy of the packet forwarded to the next host/switch. This saves a lot of memory space for the hosts and switches. All this leads to reduced overheads.