Thursday, January 28, 2010

What is Frame relay?

Frame relay is a fastest growing network communication technology and is widely used in the corporate offices, multination companies and in the ISPs. It provides cost effective, fast and secure data communication between LAN and WAN. Frame relay is based on the X.25 technology, which was initially designed for analog data transmission. It is a fastest method of transmitting the information between two similar or different networks. Frame relay is a network communication technology that is used for the data transmission between local area network and wide area network

The data is transferred in frames and they are relayed on the data link layer. The network provides permanent and fast virtual connection PVC. Frame relay provides the service between ISDN and ATM. Over the leased telephone lines, frame relay is used to connect the LAN with the fiber optic backbones and with the WAN. The data is transmitted to the destination by means of permanent of switched virtual circuits. Many virtual circuits can exist across a transmission between because virtual circuits only consume the bandwidth when they transmit the data.

The frame relay circuits are the logical circuits that are created at the time of installation and are not created by the users at their systems. In device that is a part of the frame relay network can operate at a very high speed due to the availability of the more bandwidth. The high performance and the error handing techniques allow frame relay protocol to discard the time consuming error handling techniques. The standards of the Frame relay protocols have been developed by the ANSI and CCITT. The frame relay structure is based on the LAPD protocol.

The header of the frame has the data link connection identifier DLCI and congestion bits. When a network becomes congested i.e. it is not able to transmit any new data it begins to discard the frames and these discarded frames retransmitted so more congestion is produced. To avoid this problem several methods have been developed.

Two bits Forward Explicit Congestion Notification and Backward Explicit Congestion Notification in the header of the frame are used to signal the devices at the user end that congestion has been developed. When congestions occur the FECN is changed to 1 and in this way all the downstream nodes and the attached devices at the user end learn about the congestion in the line. The BECN is changed to 1 in the frame that traveling back to the source of the data transmission. So the source is notified of the congestion in the line and to slow down the transmission until the congestion in the line is minimized.

Frame relay works on the consumer hardware such as router and switches and each switch relays the data to the next switch in frame relay network. Frame relay also work with the meshed network because each endpoint can be connected to the different locations and so on. FR is a cost effective and standardized way of creating a wide area network. Frame relay provides error free high data transmission rate and the speed comes in a number of options such as 56 KB/s, 64 KB/s, 128 KB/s, 256 KB/s, 512 KB/s, 1.5 MB/s, and 2 MB per second.

Introduction to T1/E1/T3

T1

T1 is a special type of fiber optic telephone line and it was developed by AT&T Bell Labs. T1 is the most commonly used digital transmission service in the United States. T1 line is capable of transferring the broadband digital data at very high speed i.e. 1.54 Mbps. T1 is an expensive solution for data transmission as compared to the regular telephone lines. But the prices are tend to decrease as the demand grows. Currently T1 is not cost effective for the home users.


A large number of the businesses in USA, Canada and Japan use T1 lines to connect to the internet. There are different ways to provide T1 transmission such as twisted pair cables, coaxial cable modems, fiber optic systems, common careers and digital radios.



In large networks T1 signals can be boosted up to 100 miles by using the repeaters. In telecommunication terminology, T1 is also known as DS1 and T1/DS1 is a method of connecting the digital communication systems with the telecommunication industry and North America.


E1

E1 is a digital data communication system for the European data transmission format. E1 carries the data signals at the speed of 2 Mbps (Full duplex). E1 and T1 lines can be interconnected with each other for international data transmission.

E1/T1 are used for the leased lines transmission. E1 is ideal for the voice traffic and it can carry 32 voice conversions. An E1 line 32 64-Kbps channels and each channel may be used to send and receive data and voice.

E1/PR1 (Primary rate interface) supports 30 B channels and one D channel. Primary Rate Interface (PRI) configurations are used to receive multiple analog calls from the dial-in traffic and analog-modems.

T3

A T3 line is 30 times faster than the T1 line and it supports the data transfer rate 44 Mbps. A T3 line is equivalent to 28 T1 circuits or lines and a T3 is also called a DS3. T3 is a very high speed data transmission system and it is widely used on the internet.

A T3 is capable of carrying 672 voice circuits. T3 connection is mostly used by the ISPs and corporate offices for permanent, high speed and uninterruptible internet access.