Let’s deep dive into the difference OSI layer models in detail:
Layer 1: Physical Layer in OSI
Purpose and functions
The Physical layer of OSI is basically the first and lowest layer in the OSI model. Its purpose is establishing, maintain, and terminate communication between two endpoints on different networks. It does this by defining the connection type (wired or wireless), medium of transmission (fibre optic cable, copper wire, etc.), signal types (analogue or digital) and electric voltages used in data transmission. The physical layer also handles issues related to synchronization and addressing at the media level. In addition, it defines how devices interact with each other at a hardware level so that data can be sent between them successfully.
Hardware devices and protocols associated with the physical layer
The Physical layer in OSI involves several hardware devices, such as modems, multiplexers, repeaters, and transceivers. The protocols used at this layer include Ethernet (IEEE 802.3), Token Ring (IEEE 802.5), High-Level Data Link Control (HDLC) and Point-to-Point Protocol (PPP).
Common problems that can occur at the physical layer
Common issues at this layer of OSl include signal interference caused by electrical noise or radio waves; improperly configured hardware devices; incorrect cable types or lengths; and faulty connections between two endpoints on different networks.
Layer 2: Data Link Layer in OSI
Purpose and functions
The Data Link Layer provides reliable data transmission over a physical communication link. It handles the physical addressing of each node and ensures that data is properly transferred between two connected nodes on a network. This OSI layer also defines how the network will handle data errors, retransmitting lost packets, and flow control mechanisms such as windowing.
Hardware devices and protocols associated with the data link layer
The Data Link Layer In OSI involves several hardware devices, such as frames, bridges, repeaters, and switches. The protocols used at this layer include Ethernet (IEEE 802.2), Logical Link Control (LLC) and High-Level Data Link Control (HDLC).
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Common problems that can occur at the data link layer
Common issues at the Data Link Layer in OSI include signal interference (due to electrical noise or radio waves), incorrect media types, faulty connections between two nodes, and misconfiguration of hardware devices.
Layer 3: Network Layer in OSI
Purpose and functions
This OSI Layer is mainly responsible for routing data packets from one node to another on a network. It establishes logical paths between endpoints (nodes) on a network and determines the best route for each packet to take to reach its destination. This OSI layer also handles addressing, subnetting, packet fragmentation and reassembly, and traffic congestion control mechanisms if needed.
Hardware devices and protocols associated with the network layer
The Network Layer involves several hardware devices, such as routers and gateways. The protocols used at this layer include Internet Protocol (IP), IPX, AppleTalk, and Address Resolution Protocol (ARP).
Common problems that can occur at the network layer
Common issues at the Network Layer in OSI include incorrect routing information, misconfigured routers or gateways, inefficient path selection algorithms, signal interference due to electrical noise or radio waves, and faulty connections between two nodes.
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Layer 4: Transport Layer in OSI
Purpose and functions
The Transport Layer is primarily responsible for providing reliable end-to-end delivery of data packets across a network. It segments large data units into smaller ones (called frames) so that they can be transferred more efficiently between nodes on a network. This layer in OSI also handles the retransmission of lost or damaged packets and flow control mechanisms such as sliding windows.
Hardware devices and protocols associated with the transport layer
The Transport Layer in OSI involves several hardware devices, such as bridges, repeaters, and switches. The protocols used at this layer include Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Real-Time Protocol (RTP) and Stream Control Transmission Protocol (SCTP).
Common problems that can occur at the transport layer
Common issues at the Transport Layer in OSI include incorrect packet ordering, misconfigured routers or gateways, inefficient path selection algorithms, signal interference due to electrical noise or radio waves, faulty connections between two nodes, and inadequate bandwidth.
Layer 5: Session Layer in OSI
Purpose and functions
The Session Layer in OSI is majorly responsible for creating, maintaining, and managing the communication between two endpoints (nodes) on a network. It establishes logical (virtual) connections between host systems, coordinates data exchange between nodes, handles token-passing mechanisms to control access to shared resources on a network, and provides security measures such as encryption for data integrity.
Hardware devices and protocols associated with the session layer
The Session Layer involves several hardware devices, such as routers or gateways. The protocols used at this layer include Network File System Protocol (NFS), Remote Procedure Call (RPC), and Secure Shell (SSH).
Common problems that can occur at the session layer
Common issues at this OSI Layer include incorrect packet ordering, misconfigured routers or gateways, signal interference due to electrical noise or radio waves, faulty connections between two nodes, inadequate bandwidth, and lack of data integrity.
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Layer 6: Presentation Layer in OSI
Purpose and functions
The Presentation Layer in OSI is for converting data from one format to some other so that it can be understood by both endpoints (nodes) on a network. It translates application data sent across a network into an agreed-upon format and compresses it if needed to reduce overall transmission time. This layer in OSI also provides security measures such as encryption to ensure data integrity.
Hardware devices and protocols associated with the presentation layer
The Presentation Layer involves several hardware devices, such as switches and routers. The protocols used at this layer include Hypertext Transfer Protocol or HTTP, Simple Mail Transfer Protocol or SMTP, Secure Sockets Layer (SSL) and Transport Layer Security (TLS).
Common problems that can occur at the presentation layer
Common issues at the Presentation Layer in OSI include incorrect data format, misconfigured routers or gateways, inefficient path selection algorithms, signal interference due to electrical noise or radio waves, faulty connections between two nodes, and lack of data integrity.
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Layer 7: Application Layer in OSI
Purpose and functions
The Application Layer provides services to end-users, such as file transfer, web browsing, email, and chat. This OSI layer can also provide access to network resources, such as databases and printers.
Hardware devices and protocols associated with the application layer
The Application Layer in OSI involves several hardware devices, such as servers and gateways. The protocols used at this layer include Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Simple Mail Transfer Protocol (SMTP) and Secure Sockets Layer (SSL).
Common problems that can occur at the application layer
Common issues at the Application Layer include incorrect data format, misconfigured routers or gateways, inefficient path selection algorithms, signal interference due to electrical noise or radio waves, faulty connections between two nodes, and inadequate bandwidth.
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In this guide we have learned about the OSI layers, major types of OSI Layers in detail. The OSI Layers model is an important tool for understanding the various layers of a communication network. Each layer has its function and protocols, which help enable successful data transfer between two systems. Common problems that can occur at each layer include misconfigured routers or gateways, incorrect data format, inadequate bandwidth, signal interference due to electrical noise or radio waves, faulty connections between two nodes, collisions in a network and inefficient path selection algorithms. Learning the functions of each layer is important for diagnosing any issues that may arise.
