Editing OSI model (section)

==Comparison to other networking suites==
The table below presents a list of OSI layers, the original OSI protocols, and some ''approximate'' modern matches. This correspondence is rough: the OSI model contains idiosyncrasies not found in later systems such as the IP stack in modern Internet.<ref name="Crawford">{{cite web |last1=Crawford |first1=JB |title=The actual OSI model |url=https://computer.rip/2021-03-27-the-actual-osi-model.html |date=2021-03-27}}</ref>

{| class="wikitable nowraplinks" style="line-height:1.3em;"
!colspan="2"| Layer
!rowspan="2" style="width:16.0em;"| [[Open Systems Interconnection|OSI]] protocols
!rowspan="2"| [[Internet Protocol Suite|TCP/IP protocols]]
!rowspan="2" style="width:9.0em;"| [[Signaling System 7|Signaling<br />System 7]]<ref>{{cite web|url=http://www.itu.int/rec/T-REC-Q.1400/en/|title=ITU-T Recommendation Q.1400 (03/1993)], ''Architecture framework for the development of signaling and OA&M protocols using OSI concepts''|pages=4, 7|publisher=ITU}}</ref>
!rowspan="2"| [[AppleTalk]]
!rowspan="2"| [[IPX]]
!rowspan="2"| [[Systems Network Architecture|SNA]]
!rowspan="2"| [[UMTS]]
!rowspan="2"| [[HTTP]]-based protocols
!rowspan="2"| Miscellaneous examples
|-
! No. !! Name
|-

|style="text-align:center;"| 7
| Application
| {{hlist |[[FTAM]] |[[X.400]] |[[X.500]] |[[Directory Access Protocol|DAP]] |[[Remote Operations Service Element protocol|ROSE]] |RTSE |[[Association Control Service Element|ACSE]]<ref name="ITU-T X.227">{{cite web |title=ITU-T X.227 (04/1995) |website=ITU-T Recommendations
 |date=1995-04-10 |url=https://www.itu.int/itu-t/recommendations/rec.aspx?rec=X.227 |access-date=2024-07-12}}</ref><ref name="ITU-T X.217">{{cite web |title=ITU-T X.217 |website=Open Systems Interconnection |date=1995-04-10 |url=https://www.itu.int/rec/T-REC-X.217-199504-I |access-date=2024-07-12}}</ref> |[[Common management information protocol|CMIP]]<ref name="X.700">{{cite web |title=X.700: Management framework for Open Systems Interconnection (OSI) for CCITT applications |website=ITU |date=1992-09-10 |url=https://www.itu.int/rec/T-REC-X.700-199209-I |access-date=2024-07-12}}</ref><ref name="X.711">{{cite web |title=X.711 |website=Open Systems Interconnection |date=2014-05-15 |url=https://www.itu.int/rec/T-REC-X.711/en |access-date=2024-07-12}}</ref><ref name="9596-1:1998(en)">{{cite web |title=ISO/IEC 9596-1:1998(en) |website=ISO |url=https://www.iso.org/obp/ui/#iso:std:iso-iec:9596:-1:ed-3:v1:en |access-date=2024-07-12}}</ref><ref name="9596-2:1993(en)">{{cite web |title=ISO/IEC 9596-2:1993(en) |website=ISO |url=https://www.iso.org/obp/ui/#iso:std:iso-iec:9596:-2:ed-1:v1:en |access-date=2024-07-12}}</ref>}}
| {{hlist |[[HTTP]]| [[HTTPS]] |[[FTP]] |[[SMTP]]}}
| {{hlist |[[INAP]] |[[Mobile Application Part|MAP]] |[[Transaction Capabilities Application Part|TCAP]] |[[ISDN User Part|ISUP]] |[[Telephone User Part|TUP]]}}
| {{hlist |[[Apple Filing Protocol|AFP]] |[[Zone Information Protocol|ZIP]] |[[Routing Table Maintenance Protocol|RTMP]] |[[AppleTalk#Name Binding Protocol|NBP]]}}
| {{hlist |[[Service Advertising Protocol|SAP]]}}
| {{hlist |Transaction Services |Presentation Services}}
|
| {{hlist |[[Web Browser]] |[[WebDAV]] |[[SOAP]] |[[OpenID]] |[[REST API]] |[[OAuth]] |[[GraphQL]] |[[ActivityPub]] |[[Git]] |[[DNS over HTTP]]}}
| {{hlist |[[HL7]] |[[Modbus]]|[[WebSocket]]|[[CoAP]]}}
|-

|style="text-align:center;"| 6
| Presentation
| {{hlist |ISO/IEC&nbsp;8823 |X.226 |<br />ISO/IEC&nbsp;9576-1 |X.236}}
| {{hlist |[[MIME]] |[[SSL/TLS]] |[[External Data Representation|XDR]]}}
|
| {{hlist |[[Apple Filing Protocol|AFP]]}}
|
| Presentation Services
|
| {{hlist |[[XML]] |[[JSON]] |[[MIME]] |[[Percent-encoding]] |[[base64]] |[[gzip]] |[[brotli]]}}
| {{hlist |[[Tabbed Document Interface|TDI]] |[[ASCII]] |[[EBCDIC]] |[[MIDI]] |[[MPEG]]}}
|-

|style="text-align:center;"| 5
| Session
| {{hlist |ISO/IEC&nbsp;8327 |X.225 |<br />ISO/IEC&nbsp;9548-1 |X.235}}
| [[Network socket|Sockets]] {{small|(session establishment in [[Transmission Control Protocol|TCP]]{{\}}[[Real-time Transport Protocol|RTP]]{{\}}[[PPTP]])}}
|
| {{hlist |[[AppleTalk#AppleTalk Session Protocol|ASP]] |[[AppleTalk#AppleTalk Data Stream Protocol|ADSP]] |[[AppleTalk#Printer Access Protocol|PAP]]}}
| {{hlist |[[NWLink]]}}
| {{hlist |Presentation Services |Data Flow Control}}
|
| {{hlist |HTTP [[List of HTTP header fields|headers]], including [[HTTP cookie|cookies]] |[[CSRF token]]s |[[WebSocket]]}}
| {{hlist |[[Named pipes]] |[[NetBIOS]] |[[Session Announcement Protocol|SAP]] |[[Remote Procedure Call|RPC]] |[[SOCKS]]}}
|-

|style="text-align:center;"| 4
| Transport
| {{hlist |ISO/IEC&nbsp;8073 |TP0 |TP1 |TP2 |TP3 |TP4&nbsp;(X.224) |ISO/IEC&nbsp;8602 |X.234}}
| {{hlist |[[Transmission Control Protocol|TCP]] |[[User Datagram Protocol|UDP]] |[[SCTP]] |[[QUIC]] |[[DCCP]]}}
|
| {{hlist |[[Datagram Delivery Protocol|DDP]]}}
| {{hlist |[[Sequenced packet exchange|SPX]]}}
| {{hlist|Data Flow Control |Transmission Control}}
|
| {{hlist |[[HTTP]]/[[HTTP/2]]/[[HTTP/3]] |[[WebSocket]] |[[DTLS]]}} Port number can be specified.
| {{hlist |[[NetBIOS Frames|NBF]]}}
|-

|style="text-align:center;"| 3
| Network
| {{hlist |ISO/IEC&nbsp;8208 |[[X.25]]&nbsp;([[Packet-Layer Protocol|PLP]]) |<br /> ISO/IEC&nbsp;8878 |[[CONS|X.223]] |ISO/IEC&nbsp;8473-1 |[[CLNP]]&nbsp;X.233 |ISO/IEC&nbsp;10589 |[[IS-IS]]}}
| {{hlist |[[Internet Protocol|IP]] |[[IPsec]] |[[ICMP]] |[[IGMP]] |[[OSPF]] |[[Routing Information Protocol|RIP]]}}
| {{hlist |[[Signalling Connection Control Part|SCCP]] |[[Message Transfer Part|MTP]]}}
| [[AppleTalk#AppleTalk Transaction Protocol|ATP]] {{small|([[TokenTalk]]{{\}}[[EtherTalk]])}}
| {{hlist |[[IPX]]}}
| {{hlist |Transmission Control |Path Control}}
| {{hlist |[[Radio Resource Control|RRC]]{{\}}[[Broadcast/Multicast Control|BMC]]}}
| Out of scope. [[IP address]]es can be used instead of [[domain names]] in [[URL]]s.
| {{hlist |[[NetBIOS Frames|NBF]] |[[Q.931]] }}
|-

|style="text-align:center;"| 2
| Data link
| {{hlist |ISO/IEC&nbsp;7666 |[[X.25]]&nbsp;([[LAPB]]) |<br />[[Token Bus]] |X.222 |ISO/IEC&nbsp;8802-2 |[[IEEE 802.2|LLC]]&nbsp;(type 1{{\}}2)<ref name=Cisco>{{cite web|url=http://www.cisco.com/en/US/docs/internetworking/technology/handbook/Intro-to-Internet.html#wp1020669|title=Internetworking Technology Handbook – Internetworking Basics [Internetworking]|date=15 January 2014|work=Cisco|access-date=14 August 2015}}</ref>}}
| {{hlist |[[Point-to-Point Protocol|PPP]] |[[SBTV]] |[[Serial Line Internet Protocol|SLIP]]}}
| {{hlist |[[Message Transfer Part|MTP]] |[[Message Transfer Part|Q.710]]}}
| {{hlist |[[LocalTalk]] |[[AppleTalk Remote Access|ARA]] |[[Point-to-Point Protocol|PPP]]}}
| [[IEEE 802.3|IEEE 802.3 framing]]<br />[[Ethernet II framing]]
| {{hlist |Path Control | [[Data Link Control]]}}
| {{hlist |[[PDCP]]<ref name="TS36300">{{cite web|url=http://www.3gpp.org/ftp/Specs/html-info/36300.htm|title=3GPP specification: 36.300|work=3gpp.org|access-date=14 August 2015}}</ref> |[[Logical Link Control|LLC]] |[[Medium access control|MAC]]}}
| Out of scope.
| {{hlist |[[Address resolution protocol|ARP]] | [[Neighbor Discovery Protocol|NDP (Neighbor Discovery Protocol)]] | [[Automatic repeat-request|ARQ]] | [[Asynchronous Transfer Mode|ATM]] | [[Bit stuffing]] | [[Cisco Discovery Protocol|CDP]] | [[DOCSIS]] | [[FDDI]]| [[Foundry Discovery Protocol|FDP]] | [[Fibre Channel]] | [[Frame Relay]] | [[HDLC]] | [[Ethernet|IEEE 802.3]] [[Medium access control|MAC]] | [[IEEE 802.11]] [[Medium access control|MAC]] |[[IEEE 802.1Q]] | [[Cisco Inter-Switch Link|ISL]] | [[G.hn|ITU-T G.hn DLL]] | [[Link aggregation#Linux bonding driver|Linux interface bonding]] | [[Point-to-Point Protocol|PPP]] |Q.921 |[[Token Ring]]|[[Nortel Discovery Protocol|NDP (Nortel Discovery Protocol)]] |[[IS-IS]]}}
|-

|style="text-align:center;"| 1
| Physical
| {{hlist |[[X.25]] ([[X.21bis]]|[[EIA/TIA-232]]|[[EIA/TIA-449]]|[[EIA-530]]|[[G.703]])<ref name="Cisco"/>}}
| <small>TCP/IP stack does not care about the physical medium, as long as it provides a way to communicate octets</small>
| {{hlist |[[Message Transfer Part|MTP]] |[[Message Transfer Part|Q.710]]}}
| {{hlist |[[RS-232]] |[[RS-422]] |[[PhoneNet]]}}
| 
| {{hlist |Physical}}
| [[Universal Mobile Telecommunications System#Air interfaces|UMTS air interfaces]]
| Out of scope.
| {{hlist |[[RS-232]] |[[8P8C|RJ45 (8P8C)]] |[[ITU-T V.35|V.35]] |[[ITU-T V.34|V.34]] |[[I.430]] |[[I.431]] |[[T-carrier|T1]] |[[E-carrier|E1]] |[[IEEE 802.3 PHY]] ([[10BASE-T]] |[[100BASE-TX]] |[[1000BASE-T]]) |[[Plain old telephone service|POTS]] |[[SONET]] |[[Bluetooth]] |[[Synchronous digital hierarchy|SDH]] |[[DSL]] |[[IEEE 802.11|IEEE 802.11 PHY]] |[[G.hn|ITU-T G.hn PHY]] |[[DOCSIS]] |[[DWDM]] |[[Optical Transport Network|OTN]]}}
|}

===Comparison with TCP/IP model===
{{See also|Internet protocol suite#Comparison of TCP/IP and OSI layering}}
The design of protocols in the [[TCP/IP model]] of the Internet does not concern itself with strict hierarchical encapsulation and layering. {{IETF RFC|3439}} contains a section entitled "Layering [[considered harmful]]".<ref>{{cite IETF|rfc=3439|title=Some Internet Architectural Guidelines and Philosophy|section=3|sectionname=Layering Considered Harmful|date=December 2002|access-date=25 April 2022}}</ref> TCP/IP does recognize four broad layers of functionality which are derived from the operating scope of their contained protocols: the scope of the software application; the host-to-host transport path; the internetworking range; and the scope of the direct links to other nodes on the local network.<ref>
{{cite book|title=The Illustrated Network: How TCP/IP Works in a Modern Network|author=Walter Goralski|year=2009|page=26|isbn=978-0123745415|publisher=[[Morgan Kaufmann]]|url=http://www.exa.unicen.edu.ar/catedras/comdat1/material/TP1-Ejercicio5-ingles.pdf}}</ref>

Despite using a different concept for layering than the OSI model, these layers are often compared with the OSI layering scheme in the following manner:
* The Internet [[application layer]] maps to the OSI application layer, presentation layer, and most of the session layer.
* The TCP/IP [[transport layer]] maps to the graceful close function of the OSI session layer as well as the OSI transport layer.
* The [[internet layer]] performs functions as those in a subset of the OSI network layer.
* The [[link layer]] corresponds to the OSI data link layer and may include similar functions as the physical layer, as well as some protocols of the OSI's network layer.
These comparisons are based on the original seven-layer protocol model as defined in ISO 7498, rather than refinements in the internal organization of the network layer.

The [[OSI protocols|OSI protocol suite]] that was specified as part of the OSI project was considered by many as too complicated and inefficient, and to a large extent unimplementable.<ref name="Tanenbaum 2023">{{cite book |last=Tanenbaum |first=Andrew S. |author-link=Andrew S. Tanenbaum |title=Computer networks |publisher=Prentice Hall PTR |publication-place=Upper Saddle River, NJ |year=2003 |isbn=978-0-13-066102-9 |oclc=50166590 |page=}}</ref>{{page needed|date=July 2024}} Taking the "forklift upgrade" approach to networking, it specified eliminating all existing networking protocols and replacing them at all layers of the stack. This made implementation difficult and was resisted by many vendors and users with significant investments in other network technologies. In addition, the protocols included so many optional features that many vendors' implementations were not interoperable.<ref name="Tanenbaum 2023"/>{{page needed|date=July 2024}}

Although the OSI model is often still referenced, the [[Internet protocol suite]] has become the standard for networking. TCP/IP's pragmatic approach to computer networking and to independent implementations of simplified protocols made it a practical methodology.<ref name="Tanenbaum 2023"/>{{page needed|date=July 2024}}  Some protocols and specifications in the OSI stack remain in use, one example being [[IS-IS]], which was specified for OSI as ISO/IEC 10589:2002 and adapted for Internet use with TCP/IP as RFC 1142.<ref name="RFC 1142">{{cite IETF |rfc=1142 |title=OSI IS-IS Intra-domain Routing Protocol |website=IETF Datatracker |access-date=2024-07-12}}</ref>