Asymmetric Digital Subscriber Line (ADSL) is a type of broadband communications technology that transmits digital data at a high bandwidth over existing phone lines to homes and businesses.ADSL protocol stack depicts the set of protocols and devices that are used along with ADSL.In order to access ADSL, a Digital Subscriber Line modem (DSL modem) is installed at the customer site. The DSL modem sends data bits over the local loop of the telephone network. The local loop is a two − wire connection between the subscriber’s house and the end office of the telephone company. The data bits are accepted ... Read More

Asymmetric Digital Subscriber Line (ADSL) is a type of broadband communications technology that transmits digital data at a high bandwidth over existing phone lines to homes and businesses.In order to access ADSL, a Digital Subscriber Line modem (DSL modem) is installed at the client side. The DSL modem sends data bits over the local loop of the telephone network. The local loop is a two – wire connection between the subscriber’s house and the end office of the telephone company. The data bits are accepted at the end office by a device called Digital Subscriber Line Access Multiplexer (DSLAM).Features of ... Read More

In computer networking and telecommunications, when a transmission unit is sent from the source to the destination, it contains both a header and the actual data to be transmitted. This actual data is called the payload. The header contains the protocol information as well as the source and destination addresses, which are required for delivery of the payload. The payload is required by the destination client.The following diagram depicts encapsulation of payload field in a data link layer frame. The data packet from the upper layer is framed by adding a header that contains the control information for data transmission, ... Read More

Network Control Protocol (NCP) is a set of protocols forming a part of Point − to − Point Protocol (PPP). PPP is a data link layer protocol that is used to transmit multiprotocol data between two directly connected (point-to-point) computers. PPP is composed of link control protocol (LCP), authentication protocol (AP) and network control protocol (NCP). NCPs are used for negotiating the parameters and facilities for the network layer. For every higher-layer protocol supported by PPP, one NCP is there.The following diagram illustrates the layer in which NCPs operate:List of NCPsSome of the NCPs are −Internet Protocol Control Protocol (IPCP) ... Read More

Go-Back-N Automatic Repeat reQuest (Go-Back-N ARQ), is a data link layer protocol that uses a sliding window method for reliable and sequential delivery of data frames. It is a case of sliding window protocol having to send window size of N and receiving window size of 1.Working PrincipleGo – Back – N ARQ uses the concept of protocol pipelining, i.e. sending multiple frames before receiving the acknowledgment for the first frame. The frames are sequentially numbered and a finite number of frames. The maximum number of frames that can be sent depends upon the size of the sending window. If ... Read More

In computer networking, pipelining is the method of sending multiple data units without waiting for an acknowledgment for the first frame sent. Pipelining ensures better utilization of network resources and also increases the speed of delivery, particularly in situations where a large number of data units make up a message to be sent.Flow Diagram of Pipelined Data TransmissionThe following flow diagram depicts data transmission in a pipelined system versus that in a non-pipelined system. Here, pipelining is incorporated in the data link layer, and four data link layer frames are sequentially transmitted.Data Link Protocols that uses PipeliningTwo data link layer ... Read More

Bandwidth delay product is a measurement of how many bits can fill up a network link. It gives the maximum amount of data that can be transmitted by the sender at a given time before waiting for acknowledgment. Thus it is the maximum amount of unacknowledged data.MeasurementBandwidth delay product is calculated as the product of the link capacity of the channel and the round – trip delay time of transmission.The link capacity of a channel is the number of bits transmitted per second. Hence, its unit is bps, i.e. bits per second.The round – trip delay time is the sum ... Read More

Go-Back-N protocol, also called Go-Back-N Automatic Repeat reQuest, is a data link layer protocol that uses a sliding window method for reliable and sequential delivery of data frames. It is a case of sliding window protocol having to send window size of N and receiving window size of 1.Working PrincipleGo – Back – N ARQ provides for sending multiple frames before receiving the acknowledgment for the first frame. The frames are sequentially numbered and a finite number of frames. The maximum number of frames that can be sent depends upon the size of the sending window. If the acknowledgment of ... Read More

Sliding window protocols are data link layer protocols for reliable and sequential delivery of data frames. The sliding window is also used in Transmission Control Protocol. In these protocols, the sender has a buffer called the sending window and the receiver has buffer called the receiving window.In one – bit sliding window protocol, the size of the window is 1. So the sender transmits a frame, waits for its acknowledgment, then transmits the next frame. Thus it uses the concept of stop and waits for the protocol. This protocol provides for full – duplex communications. Hence, the acknowledgment is attached ... Read More

In reliable full - duplex data transmission, the technique of hooking up acknowledgments onto outgoing data frames is called piggybacking.Why Piggybacking?Communications are mostly full – duplex in nature, i.e. data transmission occurs in both directions. A method to achieve full – duplex communication is to consider both the communication as a pair of simplex communication. Each link comprises a forward channel for sending data and a reverse channel for sending acknowledgments.However, in the above arrangement, traffic load doubles for each data unit that is transmitted. Half of all data transmission comprise of transmission of acknowledgments.So, a solution that provides better ... Read More