OSI MODEL

Layers	Functions	Network Component	Protocols
7 Application	User Interface The application layer provider different services to the application. Examples of services provided by this layer are file transfer, electronic messaging e-mail, virtual terminal access and network management.	Gateway	SSH; DNS; FTP; TFTP; BOOTP; SNMP; RLOGIN; SMTP; MIME; NFS; FINGER; TELNET; NCP; APPC; AFP; SMB
6 Presentation	Translation The Presentation layer is responsible for protocol conversion, date encryption/decryption, Expanding graphics command and the date compression. This layer makes the communications between two hosts possible.	Gateway Redirector	HTTP; SMTP; SNMP
5 Session	Syncs and Sessions This layer is responsible for establishing the process-to-process communication between the hosts in the network. This layer is responsible for establishing and ending the sessions across the network. The interactive login is an example of services provided by this layer in which the connectives are re-connected in care of any interruption.	Gateway	RPC; Named Pipes; NetBIOS; Mail Slots
4 Transport	Packets; Flow control & Error-handling This layer is responsible for end-to-end delivers of messages between the networked hosts. It first divides the streams of data into chunks or packets before transmission and then the receiving computer re-assembles the packets. It also guarantees error free data delivery without loss or duplications.	Gateway Advanced Cable Tester Router	UDP; TCP; ARP; RARP; SPX; NWLink; NetBIOS / NetBEUI; ATP
3 Network	Addressing; Routing This layer is responsible for translating the logical network address and names into their physical address (MAC address). This layer is also responsible for addressing, determining routes for sending and managing network problems such as packet switching, data congestion and routines.	Router Frame Relay Device ATM Switch Advance Cable Tester	IP; ARP; RARP, ICMP; RIP; OSFP; IGMP; IPX; NWLink; NetBEUI; DDP; DECnet
2 Data Link	Data frames to bits Data link layer is responsible for controlling the error between adjacent nodes and transfer the frames to other computer via physical layer. Data link layer is used by hubs and switches for their operation.	.	Ethernet
1 Physical	Hardware; Raw bit stream Physical Layer is responsible for transmitting row bit stream over the physical cable. The physical layer defines the hardware items such as cables, cards, voltages etc.	.	Cat-5