RSVP is a transport layer protocol that is used to reserve resources in a computer network to get different quality of services (QoS) while accessing Internet applications. It operates over Internet protocol (IP) and initiates resource reservations from the receiver’s end.FeaturesRSVP is a receiver oriented signalling protocol. The receiver initiates and maintains resource reservation.It is used both for unicasting (sending data from one source to one destination) and multicasting (sending data simultaneously to a group of destination computers).RSVP supports dynamic automatic adaptation to changes in network.It provides a number of reservation styles. It also provides support for addition of future ... Read More

Reservation protocols are the class of protocols in which the stations wishing to transmit data broadcast themselves before actual transmission. These protocols operate in the medium access control (MAC) layer and transport layer of the OSI model.In these protocols, there is a contention period prior to transmission. In the contention period, each station broadcasts its desire for transmission. Once each station announces itself, one of them gets the desired network resources based upon any agreed criteria. Since each station has complete knowledge whether every other station wants to transmit or not before actual transmission, all possibilities of collisions are eliminated.Examples ... Read More

Bit-map protocol is a collision free protocol that operates in the Medium Access Control (MAC) layer of the OSI model. It resolves any possibility of collisions while multiple stations are contending for acquiring a shared channel for transmission.In this protocol, if a station wishes to transmit, it broadcasts itself before the actual transmission. This is an example of Reservation Protocol.Working PrincipleIn this protocol, the contention period is divided into N slots, where N is the total number of stations sharing the channel. If a station has a frame to send, it sets the corresponding bit in the slot.Suppose that there ... Read More

In computer networks, when more than one station tries to transmit simultaneously via a shared channel, the transmitted data is garbled. This event is called collision. The Medium Access Control (MAC) layer of the OSI model is responsible for handling collision of frames. Collision – free protocols are devised so that collisions do not occur. Protocols like CSMA/CD and CSMA/CA nullifies the possibility of collisions once the transmission channel is acquired by any station. However, collision can still occur during the contention period if more than one stations starts to transmit at the same time. Collision – free protocols resolves ... Read More

Multi-access ChannelsMulti-access channels are network channels that allow several transmitters to communicate with a common receiver via a shared channel. These channels are also called multiple access (MAC) channels. The network channel may be a single cable or optical fiber connecting multiple nodes, or a portion of the wireless spectrum.Random Access ChannelsRandom-access channels (RACH) are shared channels used in wireless communication systems to allow mobile devices for call set-up. RACH also handles bursty data transmission. RACH is popularly used by GSM mobiles for transmission over cellular networks.Multiple Access SchemesBoth multi-access channels and random access channels require a scheme to allow ... Read More

Link Control Protocol (LCP) is a part of Point – to – Point Protocol (PPP) that operates in the data link layer. It is responsible for establishing, configuring, testing, maintaining and terminating links for transmission. It also imparts negotiation for set up of options and use of features by the two endpoints of the links.Working PrincipleWhen PPP tries to communicate, it sends out LCP packets prior to the establishment of connections over the point – to – point link. The LCP packets check the communication line to ascertain whether it can sustain the data volume at the required speed. Accordingly, ... Read More

Serial Line Internet Protocol (SLIP) is a simple protocol that works with TCP/IP for communication over serial ports and routers. They provide communications between machines that were previously configured for direct communication with each other.For example, a client may be connected to the Internet service provider (ISP) with a slower SLIP line. When a service is required, the client places a request to the ISP. The ISP responds to the request and passes it over to the Internet via high speed multiplexed lines. The ISP then sends the results back to the client via the SLIP lines.SLIP was developed by ... Read More

Synchronous optical networking (SONET) is a physical layer protocol for transmitting multiple digital bit streams over optical fiber links that form the backbone of the communication networks. Packet-over-SONET (POS) is a standard that maps IP packets into SONET frames. To implement this mechanism, Point – to – Point Protocol (PPP) runs on IP routers. Point – to – Point Protocol (PPP) is a data link layer protocol that is used to transmit data between two directly connected (point-to-point) computers. It is a byte-oriented protocol that is widely used in broadband communications having heavy loads and high speeds.The following diagram shows ... Read More

The data link protocols operate in the data link layer of the Open System Interconnections (OSI) model, just above the physical layer.The services provided by the data link protocols may be any of the following −Framing − The stream of bits from the physical layer are divided into data frames whose size ranges from a few hundred to a few thousand bytes. These frames are distributed to different systems, by adding a header to the frame containing the address of the sender and the receiver.Flow Control − Through flow control techniques, data is transmitted in such a way so that ... Read More

Selective repeat protocol, also called Selective Repeat ARQ (Automatic Repeat reQuest), is a data link layer protocol that uses sliding window method for reliable delivery of data frames. Here, only the erroneous or lost frames are retransmitted, while the good frames are received and buffered.It uses two windows of equal size: a sending window that stores the frames to be sent and a receiving window that stores the frames receive by the receiver. The size is half the maximum sequence number of the frame. For example, if the sequence number is from 0 – 15, the window size will be ... Read More