UML/OSI

OSI Model
	Data unit	Layer	Function
Host layers	Data	7. Application	Network process to application
		6. Presentation	Data representation and encryption
		5. Session	Interhost communication
	Segment	4. Transport	End-to-end connections and reliability
Media layers	Packet	3. Network	Path determination and logical addressing
	Frame	2. Data Link	Physical addressing
	Bit	1. Physical	Media, signal and binary transmission

The OSI Model is the Open System Interconnection Reference Model. In its most basic form, it divides network architecture into seven layers which, from top to bottom, are the Application, Presentation, Session, Transport, Network, Data-Link, and Physical Layers. It is therefore often referred to as the OSI Seven Layer Model.

The OSI model can be used to conceptualize complex networks of people, places, and machines. UML diagram elements can be structured in layers that correspond to the 7-layer OSI model. Currently there is growing interest in the use of UML for system modeling. Structuring specifications is difficult, but The ITU (International Telecommunications Union), the IEC (International Electrotechnical Commission) and the ISO have jointly defined some UML profiles for a Reference Model of Open Distributed Processing (RM-ODP).

Physical

Media, signal and binary transmission

Protocols: RS-232, V.35, V.34, I.430, I.431, T1, E1, 802.3 Ethernet, 10BASE-T, 100BASE-TX, POTS, SONET, DSL, 802.11a/b/g/n PHY, ITU-T G.hn PHY

Data Link

Physical addressing

Protocols: ARP, CSLIP, SLIP, Frame Relay, ITU-T G.hn DLL

Network

Path determination and logical addressing

Protocols: IP, ICMP, IPsec, IGMP

Transport

End-to-end connections and reliability

Protocols: TCP, UDP, PPTP, L2TP, SCTP

Session

Interhost communication

Protocols: Named Pipes, NetBIOS, SAP

Presentation

Data representation and encryption

Protocols: MIME, XDR, SSL, TLS

Application

Network process to application

Protocols: NNTP, SIP, SSI, DNS, FTP, Gopher, HTTP, NFS, NTP, SMPP, SMTP, SNMP, Telnet, (more)