Layers of Protocol (OSI Model)

Layers of Protocol (OSI Model)

The 7 layers of the OSI models can be divided into upper and lower layers. I have defined the characteristics, tasks and features of each layer separately.


Layer 7: Application Layer
The application layer defines the interfaces for communication and data transfer.
This layer also provides and support services such as job transfer, handles network access, e-mail, supports user applications and error recovery.
 Protocols: FTP, DNS, SNMP, SMTP, FINGER, TELNET, TFTP, BOOTP and SMB protocol are operated on the application layer.
Network Devices: Gateway network device is operated on the application layer.

Gateway network

Layer 6:Presentation Layer
describes the syntax of data being transferred.
Example: this layer describes how floating point numbers can be exchanged between hosts with different math formats.
Protocol

Apple Filing Protocol (AFP)

Independent Computing Architecture (ICA), the Citrix system core protocol

Lightweight Presentation Protocol (LPP)

NetWare Core Protocol (NCP)

Network Data Representation (NDR)

Telnet (a remote terminal access protocol)

eXternal Data Representation (XDR)

X.25 Packet Assembler/Disassembler Protocol (PAD)
Network Devices: Gateway Redirector is operates on the presentation layer

Gateway Redirector 

Layer 5: Session Layer

describes the organization of data sequences larger than the packets handled by lower layers.
Example: this layer describes how request and reply packets are paired in a remote procedure call.
Protocols: The protocols that work on the session layer are NetBIOS, Mail Slots, Names Pipes, RPC
 Network Devices: Gateway

Gateway

Layer 4: Transport Layer
describes the quality and nature of the data delivery.
Example: this layer defines if and how retransmissions will be used to ensure data delivery.
Protocols: These protocols work on the transport layer TCP, SPX, NETBIOS, ATP and NWLINK.
Network Devices: The Brouter, Gateway and Cable tester work on the transport layer.

Brouter

Layer 3: Network Layer
describes how a series of exchanges over various data links can deliver data between any two nodes in a network.
Example this layer defines the addressing and routing structure of the Internet.
Protocols: These protocols work on the network layer IP, ICMP, ARP, RIP, OSI, IPX and OSPF.
Network Devices: Network devices including Router, Brouter, Frame Relay device and ATM switch devices work on the network layer.

Router

Layer 2:Data Link Layer
describes the logical organization of data bits transmitted on a particular medium.
Example: this layer defines the framing, addressing and checksumming of Ethernet packets.
Protocols: Logical Link Control
• error correction and flow control
• manages link control and defines SAPs
802.1 OSI Model
802.2 Logical Link Control
Media Access Control
• communicates with the adapter card
• controls the type of media being used:
802.3 CSMA/CD (Ethernet)
802.4 Token Bus (ARCnet)
802.5 Token Ring
802.12 Demand Priority
Network Devices: Bridge
Switch
ISDN Router
Intelligent Hub
NIC
Advanced Cable Tester

Advanced Cable Tester

Layer 1: Physical Layer
describes the physical properties of the various communications media, as well as the electrical properties and interpretation of the exchanged signals.
Example:this layer defines the size of Ethernet coaxial cable, the type of BNC connector used, and the termination method.
Protocols: Protocols that work on the physical layer are ISDN, IEEE 802 and IEEE 802.2
Network Devices: Hubs, Repeaters, Oscilloscope and Amplifier works on the network devices.

 Hubs

Repeaters

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