Data Link Layer Protocol

5 min readNov 24, 2022

Introduction

Typically, the only thing that data link layer protocols need to do is make sure and check that the bits and bytes being received match the bits and bytes being conveyed. It is essentially a set of standards used to construct the data link layer. The second tier of the seven-layer OSI model of computer networking is known as the data link layer, or layer 2. This layer is the protocol layer that crosses the physical layer to transport data between nodes on a network segment. In addition to providing the functional and procedural means for data transfer between network entities, the data link layer may also enable the detection and potential correction of problems that may develop in the physical layer. Local frame delivery between nodes on the same level of the network is handled by the data link layer. These protocol data units, known as data-link frames, do not travel outside of a local area network. Data-link protocols can concentrate on local delivery, addressing, and media arbitration because inter-network routing and global addressing are higher-layer activities.

Data Link Layer

The main responsibility of the Data Link Layer is to transfer the datagram across an individual link. The Data link layer protocol defines the format of the packet exchanged across the nodes as well as the actions such as Error detection, retransmission, flow control, and random access. The Data Link Layer protocols are Ethernet, token ring, FDDI and PPP. An important characteristic of a Data Link Layer is that datagrams can be handled by different link layer protocols on different links in a path. For example, the datagram is handled by Ethernet on the first link, PPP on the second link

Data Link layer Protocols

Examples of data link protocols are Ethernet for local area networks (multi-node), the Point-to-Point Protocol (PPP), HDLC and ADCCP for point-to-point (dual-node) connections. In the Internet Protocol Suite (TCP/IP), the data link layer functionality is contained within the link layer, the lowest layer of the descriptive model.

A. Synchronous Data link protocol(SDLP)

In essence,SDLC is basically a communication protocol for computers. It usually supports multipoint links even error recovery or error correction also. It is usually used to carry SNA (Systems Network Architecture) traffic and is the present precursor to HDLC. It was also designed and developed by IBM in 1975. It is also used to connect all of the remote devices to mainframe computers at central locations may be in point-to-point (one-to-one) or point-to-multipoint (one-to-many) connections. It is also used to make sure that the data units should arrive correctly and with right flow from one network point to the next network point.

B.High-Level Data Link Protocol (HDLC)

HDLC is basically a protocol that is now assumed to be an umbrella under which many Wide Area protocols sit. It was originally created and developed by ISO in 1979. This protocol is generally based on SDLC. It also provides best-effort unreliable service and also reliable service. HDLC is a bit-oriented protocol that is applicable for point-to-point and multipoint communications.

C. Serial Line Interface Protocol (SLIP)

The only purpose of SLIP, an older protocol, is to add a framing byte to the end of an IP packet. It functions essentially as a data link control facility that is necessary for the dial-up IP packet transfer between an Internet Service Provider (ISP) and a home user. It is an encapsulation of TCP/IP that was created specifically to work over multiple router connections and serial ports for communication. It has some drawbacks, such as the absence of mechanisms for error detection or correction.

D. Point to Point Protocol (PPP)

The most reliable protocol is used to transport not only IP packets but also other kinds of packets. Additionally, dial-up and leased router-router lines may need it. In essence, it offers a framing technique to describe frames. This character-oriented protocol also has an error-detection function. Additionally, it is employed to deliver the NCP and LCP protocols. While NCP is used to negotiate network-layer protocols, LCP is used to bring lines up, negotiate options, and bring them down. It is necessary for similar serial interfaces to HDLC.

E. Link Control Protocol (LCP)

It was first created and developed by IEEE 802.2. Additionally, it is employed to offer HDLC-style services on LAN. For the purposes of establishing, configuring, testing, maintaining, and ending or terminating links for the transmission of data frames, LCP is essentially a PPP protocol.

F. Link Access Procedure (LAP)

LAP protocols, or data link layer protocols, are necessary for framing and moving data over point-to-point links. It also has a few features for reliability services. LAPB (Link Access Procedure Balanced), LAPD (Link Access Procedure D-Channel), and LAPF are the three main types of LAP (Link Access Procedure Frame-Mode Bearer Services). Actually, IBM SDLC, which is being submitted to the ISP purely for standardization, is where it came from.

G. Network Control Protocol (NCP) –

NCP was an additional older protocol that ARPANET used. In essence, it enables users to access computers and a few other devices at distant locations and transfer files between two or more computers. PPP is typically made up of a collection of protocols. For every higher-layer protocol that PPP supports, NCP is always available. TCP/IP took over from NCP in the 1980s.

Group 35 -

Swapnil Mhoprekar

Tanish Modase

Gautam Mudawadkar

Prathmesh Nagpure

Data Link Layer Protocol

Introduction

Data Link Layer

Data Link layer Protocols

Some more Data Link Layer protocols

Written by Sameermudawadkar