Data link layer protocols are responsible for ensuring accurate transmission of bits and bytes. They comprise a set of specifications implemented directly above the physical layer of the OSI model. The layer is tasked with detecting data frames, media access, error control and multiplexing data streams. SDLC is a communication protocol that supports multipoint connections and error correction, used for transmitting SNA traffic. HDLC, based on SDLC, provides reliable and unreliable services. PPP is an example of point-to-point protocol used for connecting to the internet. Bit transmission in point-to-point connections is orderly, with no competition such as in shared media LANs.
What are Data Link Layer Protocols?
Data Link Layer protocols are a set of specifications used to implement the data link layer directly above the physical layer of the OSI (Open System Interconnections) model. These protocols are responsible for ensuring that the bits and bytes received are identical to the bits and bytes transmitted. They are crucial for ensuring reliable point-to-point and point-to-multipoint connections in a communication network.
What is SDLC?
SDLC (Synchronous Data Link Control) is a communication protocol for computers that was designed and developed by IBM in 1975. It supports multipoint connections, error recovery, and error correction and is generally used to transmit Systems Network Architecture (SNA) traffic. SDLC is also used to connect all remote devices to mainframes at central sites in point-to-point or point-to-many connections. Its main function is to ensure that data units travel correctly and with the correct flow from one network point to the next.
What is HDLC?
HDLC (High-Level Data Link Control) is based on SDLC and provides both unreliable and reliable services. It is a bit-oriented protocol that is suitable for both point-to-point and multipoint communication. The PPP (Point-to-Point Protocol), which is used to connect to the Internet via a dial-up modem, is an example of a data transmission protocol that uses HDLC. Unlike shared media LANs, where multiple stations try to use the network, there is no competition with HDLC since the connection between two systems is always a point-to-point connection, ensuring that the bits are always transmitted in the correct order from the sender to the receiver.
The final outcome
Data Link Layer protocols play a critical role in ensuring reliable communication in a network. SDLC and HDLC are two widely used protocols that provide the necessary services for point-to-point and multipoint communication. With the ever-increasing demand for reliable and efficient networks, a firm understanding of these protocols is essential for anyone involved in network design and communication.