Limited Contention Protocols are the media access control (MAC) protocols that combines the advantages of collision based protocols and collision free protocols. They behave like slotted ALOHA under light loads and bitmap protocols under heavy loads.ConceptIn computer networks, when more than one station tries to transmit simultaneously via a shared channel, the transmitted data is garbled, an event called collision. In collision based protocols like ALOHA, all stations are permitted to transmit a frame without trying to detect whether the transmission channel is idle or busy. In slotted ALOHA, the shared channel is divided into a number of discrete time ... Read More

Binary Countdown Protocol is a collision-free protocol that operates in the Medium Access Control (MAC) layer of the OSI model. In computer networks, when more than one station tries to transmit simultaneously via a shared channel, the transmitted data is garbled, an event called collision. Collision-free protocols resolves channel access while the stations are contending for the shared channel, thus eliminating any possibilities of collisions.Working Principle of Binary CountdownIn a binary countdown protocol, each station is assigned a binary address. The binary addresses are bit strings of equal lengths. When a station wants to transmit, it broadcasts its address to ... Read More

Resilient Packet Ring (RPR), standardized as IEEE 802.17, is a protocol standard for data transmission over fiber optic ring networks, that operates in the Media Access Control (MAC) layer of the Open Systems Interconnection (OSI) model. It provides a packet based transmission facility, with the aim of improving efficiency of Ethernet and IP services. RPR provides improved bandwidth utilization and throughput, greater speed of deployment, and optimized equipment and operational costs.Working PrincipleThe stations in a RPR are connected by dual counter rotating fiber optic rings called ringlets. Transmission occurs along both the rings. This helps to utilize the total available ... Read More

Fiber Distributed Data Interface (FDDI) is a set of ANSI and ISO standards for transmission of data in local area network (LAN) over fiber optic cables. It is applicable in large LANs that can extend up to 200 kilometers in diameter.FeaturesFDDI uses optical fiber as its physical medium.It operates in the physical and medium access control (MAC layer) of the Open Systems Interconnection (OSI) network model.It provides high data rate of 100 Mbps and can support thousands of users.It is used in LANs up to 200 kilometers for long distance voice and multimedia communication.It uses ring based token passing mechanism ... Read More

Token RingToken ring (IEEE 802.5) is a communication protocol in a local area network (LAN) where all stations are connected in a ring topology and pass one or more tokens for channel acquisition. A token is a special frame of 3 bytes that circulates along the ring of stations. A station can send data frames only if it holds a token. The tokens are released on successful receipt of the data frame.Token Passing Mechanism in Token RingIf a station has a frame to transmit when it receives a token, it sends the frame and then passes the token to the ... Read More

Token Bus (IEEE 802.4) is a standard for implementing token ring over the virtual ring in LANs. The physical media has a bus or a tree topology and uses coaxial cables. A virtual ring is created with the nodes/stations and the token is passed from one node to the next in a sequence along this virtual ring. Each node knows the address of its preceding station and its succeeding station. A station can only transmit data when it has the token. The working principle of the token bus is similar to Token Ring.Token Passing Mechanism in Token BusA token is ... 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. Every station gets its turn for transmission in a predefined order. A method to accomplish this is to use the method of token passing.Token Passing MechanismA token is a small message that circulates among the stations of a computer network providing permission to the stations for ... Read More

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