Derived from ISO/IEC 7498-1

OSI Seven-Layer Reference Model

The seven OSI layers with what each does and the protocols that live there, as one downloadable reference figure.

All templates

OSI seven layer model: the ISO/IEC 7498-1 reference stack

The seven layers of the OSI Basic Reference Model stacked from layer 7 Application at the top to layer 1 Physical at the bottom, each with its number, official name, core function and canonical protocol examples.

OSI seven layer model: the ISO/IEC 7498-1 reference stack The seven layers of the Open Systems Interconnection Basic Reference Model from ISO/IEC 7498-1:1994, published jointly by ISO and IEC. The bands stack from layer 7 Application at the top, through Presentation, Session, Transport, Network and Data Link, to layer 1 Physical at the bottom. Each band lists the layer number, official name, core function, protocol data unit and example protocols. Side labels mark layers 7 to 4 as the host layers and layers 3 to 1 as the media layers. 7 Application User-facing protocols and APIs HTTP, SMTP, FTP, DNS Unit: Data 6 Presentation Encoding, encryption and compression TLS, JPEG, ASCII, Unicode Unit: Data 5 Session Establish and maintain conversations NetBIOS, RPC, SMB Unit: Data 4 Transport End-to-end delivery and reliability TCP, UDP, QUIC Unit: Segment 3 Network Routing across interconnected networks IP, ICMP, OSPF, BGP Unit: Packet 2 Data Link Frame delivery on the local segment Ethernet, PPP, ARP Unit: Frame 1 Physical Bits on the wire or radio Cable, Fibre, Wi-Fi PHY Unit: Bit HOST LAYERS Layers 7 to 4 MEDIA LAYERS Layers 3 to 1 Source: ISO/IEC 7498-1:1994, OSI Basic Reference Model

Read the stack top down to follow data leaving an application, and bottom up to follow it arriving. Layers 7 to 4 are the host layers that live in end systems; layers 3 to 1 are the media layers that move bits between them. ISO/IEC 7498-1:1994 defines the model.

When a conversation needs the layers named precisely, from physical media to application.

What you need and what you get

You'll get

  • The reference model figure, downloadable as PNG or PowerPoint

Derived from ISO/IEC 7498-1:1994, OSI Basic Reference Model. ISO. All rights reserved by the publisher.