| Layer | Protocol data unit (PDU) | Function | ||
|---|---|---|---|---|
| Host layers | 7 | Application | Data | High-level protocols such as for resource sharing or remote file access, e.g. HTTP |
| 6 | Presentation | Translation of data between a networking service and an application; including character encoding, data compression and encryption/decryption | ||
| 5 | Session | Managing communication sessions, i.e., continuous exchange of information in the form of multiple back-and-forth transmissions between two nodes | ||
| 4 | Transport | Segment, Datagram | Reliable transmission of data segments between points on a network, including segmentation, acknowledgement and multiplexing | |
| Media layers | 3 | Network | Packet | Structuring and managing a multi-node network, including addressing, routing and traffic control |
| 2 | Data link | Frame | Transmission of data frames between two nodes connected by a physical layer | |
| 1 | Physical | Bit, Symbol | Transmission and reception of raw bit streams over a physical medium | |
OSI Model Example #
7. Application Layer #
- NNTP
- SIP
- SSI
- DNS
- FTP
- Gopher
- HTTP
- NFS
- NTP
- SMPP
- SMTP
- DHCP
- SNMP
- Telnet
- Netconf
- …
6. Presentation Layer #
- MIME
- XDR
- TLS
- SSL
5. Session Layer #
- Named Pipes
- NetBIOS
- SAP
- L2TP
- PPTP
4. Transport Layer #
- TCP
- UDP
- SCTP
- DCCP
- SPX
3. Network Layer #
- IP (IPv4, IPv6)
- ICMP
- IPsec
- IGMP
- IPX
- AppleTalk
2. Data Link Layer #
- ATM
- SDLC
- HDLC
- ARP
- CSLIP
- SLIP
- PLIP
- IEEE 802.3
- Frame Relay
- ITU-T G.hn DLL
- PPP
- X.25
1. Physical Layer #
- EIA/TIA-232
- EIA/TIA-449
- ITU-T V-Series
- I.430
- I.431
- POTS
- 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