TCP/IP Model Layers Cheat Sheet

The Open Systems Interc­onn­ection model (OSI Model) is a conceptual model that charac­terizes and standa­rdizes the commun­ication functions of a teleco­mmu­nic­ation or computing system without regard of their underlying internal structure and techno­logy. Its goal is the intero­per­ability of diverse commun­ication systems with standard protocols. The model partitions a commun­ication system into abstra­ction layers. The original version of the model defined seven layers. A layer serves the layer above it and is served by the layer below it.

High-level APIs, including resource sharing, remote file access, directory services and virtual terminals

Transl­ation of data between a networking service and an applic­ation; including character encoding, data compre­ssion and encryp­tio­n/d­ecr­yption

Managing commun­ication sessions, i.e. continuous exchange of inform­ation in the form of multiple back-a­nd-­forth transm­issions between two nodes

Reliable transm­ission of data segments between points on a network, including segmen­tation, acknow­led­gement and multip­lexing
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Struct­uring and managing a multi-node network, including addres­sing, routing and traffic control
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Reliable transm­ission of data frames between two nodes connected by a physical layer

Transm­ission and reception of raw bit streams over a physical medium

TCP/IP provides end-to-end connec­tivity specifying how data should be packet­ized, addressed, transm­itted, routed and received at the destin­ation. This functi­onality is organized into four abstra­ction layers which are used to sort all related protocols according to the scope of networking involved.
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Applic­ation layer includes all the higher­-level protocols:
Telnet
X Windows
SSH (Secure SHell)
FTP (File Transfer Protocol)
DNS (Domain Naming System)
RDP (Remote Desktop Protocol)
HTTP (Hypertext Transfer Protocol)
SMTP (Simple Mail Transfer Protocol)
DHCP (Dynamic Host Config­uration Protocol)
SNMP (Simple Network Management Protocol)
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Provides commun­ication session management between computers. Defines the level of service and status of the connec­tio­n.The main protocols included at Transport layer are: TCP (Trans­mission Control Protocol) and UDP (User Datagram Protocol).

Packages data into IP datagrams, containing source and destin­ation address inform­ation used to forward datagrams between hosts and across networks. Protocols are: IP (Internet Protocol), ICMP(I­nternet Control Message Protocol), ARP (Address Resolution Protocol), RARP (Reverse Address Resolution Protocol)

Specifies how data is physically sent through the network, including how bits are electr­ically signaled by hardware devices that interface directly with a network medium, such as: Coaxial cable, Optical fiber, Twiste­d-pair copper wire,, Ethernet, RS-232
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