Model of communication of seven abstraction layers
OSI model by layer
7. Application layer
NNTP
SIP
SSI
DNS
FTP
Gopher
HTTP (HTTP/3)
NFS
NTP
SMPP
SSH
SMTP
SNMP
Telnet
DHCP
NETCONF
more....
6. Presentation layer
MIME
XDR
ASN.1
ASCII
TLS
PGP
5. Session layer
Named pipe
NetBIOS
SAP
PPTP
RTP
SOCKS
X.225[1]
4. Transport layer
TCP
UDP
SCTP
DCCP
QUIC
SPX
3. Network layer
IP
IPv4
IPv6
ICMP (ICMPv6)
IPsec
IGMP
IPX
IS-IS
AppleTalk
X.25
PLP
2. Data link layer
ATM
ARP
SDLC
HDLC
CSLIP
SLIP
GFP
PLIP
IEEE 802.2
LLC
MAC
L2TP
IEEE 802.3
Frame Relay
ITU-T G.hn DLL
PPP
X.25 LAPB
Q.922 LAPF
IEEE 802.11
1. Physical layer
RS-232
RS-449
ITU-T V-Series
I.430
I.431
PDH
SONET/SDH
PON
OTN
DSL
IEEE 802.3
IEEE 802.11
IEEE 802.15
IEEE 802.16
IEEE 1394
ITU-T G.hn PHY
USB
Bluetooth
v
t
e
The Open Systems Interconnection (OSI) model is a reference model from the International Organization for Standardization (ISO) that "provides a common basis for the coordination of standards development for the purpose of systems interconnection."[2] In the OSI reference model, the communications between systems are split into seven different abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.[3]
The model partitions the flow of data in a communication system into seven abstraction layers to describe networked communication from the physical implementation of transmitting bits across a communications medium to the highest-level representation of data of a distributed application. Each intermediate layer serves a class of functionality to the layer above it and is served by the layer below it. Classes of functionality are realized in all software development through all standardized communication protocols.
Each layer in the OSI model has well-defined functions, and the methods of each layer communicate and interact with those of the layers immediately above and below as appropriate.
The Internet protocol suite as defined in RFC 1122 and RFC 1123 is a model of networking developed contemporarily to the OSI model, and was funded primarily by the U.S. Department of Defense. It was the foundation for the development of the Internet. It assumed the presence of generic physical links and focused primarily on the software layers of communication, with a similar but much less rigorous structure than the OSI model.
In comparison, several networking models have sought to create an intellectual framework for clarifying networking concepts and activities,[citation needed] but none have been as successful as the OSI reference model in becoming the standard model for discussing and teaching networking in the field of information technology. The model allows transparent communication through equivalent exchange of protocol data units (PDUs) between two parties, through what is known as peer-to-peer networking (also known as peer-to-peer communication). As a result, the OSI reference model has not only become an important piece among professionals and non-professionals alike, but also in all networking between one or many parties, due in large part to its commonly accepted user-friendly framework.[4]
Communication in the OSI model (example with layers 3 to 5)
^"X.225 : Information technology – Open Systems Interconnection – Connection-oriented Session protocol: Protocol specification". Archived from the original on 1 February 2021. Retrieved 10 March 2023.
^ISO/IEC 7498-1:1994 Information technology — Open Systems Interconnection — Basic Reference Model: The Basic Model. June 1999. Introduction. Retrieved 26 August 2022.
^"What is the OSI Model?". Forcepoint. 10 August 2018. Retrieved 20 May 2022.
^Tomsho, Greg (2016). Guide to Networking Essentials (7th ed.). Cengage. Retrieved 3 April 2022.
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the OSImodel, a more comprehensive reference framework for general networking systems. Initially referred to as the DOD Internet Architecture Model, the...
In the seven-layer OSImodel of computer networking, the network layer is layer 3. The network layer is responsible for packet forwarding including routing...
specified in both the Internet Protocol Suite (TCP/IP) and the OSImodel. Although both models use the same term for their respective highest-level layer...
Commerce mandated compliance with the OSImodel, while the US Department of Defense planned to transition from TCP/IP to OSI. Meanwhile, the development of a...
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top-level SDU, the letter itself, emerges. Protocol data units of the OSImodel are: The Layer 4: transport layer PDU is the segment or the datagram....
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specifications use terminology from the seven-layer OSImodel rather than the TCP/IP model. The TCP/IP model, in general, does not consider physical specifications...
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the seven-layer OSImodel is often used as a reference for teaching and documentation, the protocols originally conceived for the model did not gain popularity...
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stack is a] set of network protocol layers that work together. The OSI Reference Model that defines seven protocol layers is often called a stack, as is...
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the general design of network communication protocols. They employ the OSImodel as a basis for their development in which they characterize system elements...
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specific types of hardware links. The Open Systems Interconnection model (OSImodel) defines and codifies the concept of layered network architecture. Abstraction...
protocols such as Modbus, at the cost of higher complexity. In terms of the OSImodel for networks, DNP3 specifies a layer 2 protocol. It provides multiplexing...
layer of the TCP/IP model is easily compared directly with the network layer (layer 3) in the Open Systems Interconnection (OSI) protocol stack, the...
transmission medium. These two sublayers together correspond to layer 2 of the OSImodel. For compatibility reasons, LLC is optional for implementations of IEEE...
details of a subsystem. Examples of software models that use layers of abstraction include the OSImodel for network protocols, OpenGL, and other graphics...
uses the first and second layers of the OSImodel, UDS utilizes the fifth and seventh layers of the OSImodel. The Service ID (SID) and the parameters...
This implementation takes place at the physical level (layer) of the OSImodel network structure. Examples of wireless networks include cell phone networks...
network include electrical cable, optical fiber, and free space. In the OSImodel, the software to handle the media is defined at layers 1 and 2 — the physical...
in the link layer (layer 2 in the OSImodel), such as Ethernet multicast, and at the internet layer (layer 3 for OSI) for Internet Protocol Version 4 (IPv4)...
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