Frame Relay frame relay is a packet switching technology that 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 virtual connection. It uses a technology called fast packet in which error checking does not occur in any intermediate node of the transmission but done at the ends.
It makes it more efficient than X. Another advantage is that you need less powerful switching centers nodes and with less memory capacity than those needed by X25 each X25 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 Frame relay has evolved from X. Error correction is done on an end-to-end basis rather than a link -to-link basis as in X.
Frame relay can support multiple users over the same line and can establish a 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 connection of LANs, the combination of low throughput, delay variation and frame discard when the link is congested will limit its usefulness to multimedia. 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: 1. The call control packets are used for setting up and clearing virtual circuits.
Frame relay layers pdf printer
In band signaling is used. Multiplexing of virtual circuits takes place at layer 3. Layer 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 a connectionless service, 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. Features of frame relay: Some important features of frame relay are : 1. Frame relay operates at a high speed 1. Frame relay operates only in the physical and data link layers. So it can be easily used in Internet. It allows the bursty data. It has a large frame size of 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 control. The 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 user can use any protocol which is recognized by ANSI.
Some of the important reasons are as follows: 1. Higher data rates. It allows transfer of bursty data. It has lower overheads. Higher Data Rates It allows transfer of bursty data. Interconnect them using the T lines. Interconnect using the frame relay. Hence we need 6 T-lines to connect each LAN to the remaining three. This requires only 4 T-lines.
11-13 Frame Relay Configuration
The saving increases with increase in the number of LANs. That means a large amount of data data burst is sent suddenly, then for sometime there is very little or no data. It supports a minimum average data rate and can handle the bursty data.
The error checking takes place only at the destination. This saves a lot of memory space of the hosts and switches. Shows the frame relay network connected to internet. This is actually a number which identifies a virtual circuit in frame relay.
For this each switch has a table. How frame relay works?
These virtual circuits are created and used in the data link layer. Frame relay frame: The structure of the Frame Relay frame shown in the figure. The Frame Relay package, very similar to the X. This frame is very similar to the HDLC frame except for the missing control field here. They together form a 10 bit data link connection identifier. It is not used by the frame relay protocol. In the overload situations a frame may have to be discarded.
Extended address Frame Relay Assembler I Disassembler : The frame relay address has been extended from the original 2 byte address to 3 or 4 byte address, in order to increase the range of DLCIs. Its long form is Voice Over Frame Relay. Voice is transferred in the digital form with the help of PCM.
But the quality of sound is not very good. A mechanism to check if data is flowing. A multicast mechanism. A mechanism to check the status of a switch. Congestion control and quality of service: One of the advantages of frame relay is that it provides congestion control and quality of service.
Advantages of frame relay: Some of the advantages of frame relay are: 1.
Streamlined communication process. The number of functions of a protocol at the user-network interface is reduced. Lower delay. Higher throughput.
Frame relay can be used at access speeds upto 2 Mbps. Frame Relay is cost- effective, partly due to the fact that the network buffering requirements are carefully optimized.
Compared to X. Frame Relay is also much faster than X. Disadvantages of frame relay: 1. Frames are delivered unreliably. Packets may not be delivered in the same sequence as that at the sending end. Packets having errors are simply discarded. Frame relay does not provide flow control.
It does not provide the acknowledgement of received packets. Frame discarded in case of network congestion.
7. Frame Relay Virtual Circuits
If congestion occurs in the network, frame data is discarded within the network without retransmission of this frame. The sender must perform retransmission control at his own responsibility.
It is useful in identifying the less important traffic which can be dropped in the event of congestion. The flow control can then be initiated or the indication may be ignored. Above that layer the protocol may be determined as desired by the user.
Therefore, the IP protocol the third-layer protocol which is commonly used for LAN can be used without any modification. Dinesh authors the hugely popular Computer Notes blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps.
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