Understanding The OSI Model

[Upper layers]
7. Application:
Provides interface between software applications and network for interpreting applications’ requests and requirements.
6. Presentation:
Allows hosts and applications to use a common language; performs data formatting, encryption, and compression. a.k.a. “syntax layer”.
5. Session:
Establishes, maintains, and terminates user connections.
[Lower layers]
4. Transport:
Ensures accurate delivery of data through flow control, sementation and reassembly, error correction and acknowledgement. (TCP)
3. Network:
Establishes network connections; translates network address into their physical counterparts and determines routing through logical addressing (IP addresses).
2. Data link:
Packages data into frames appropriate to network transmission method.
2a. Logical Link Control (LLC) Sublayer:
Addressing and channel access control mechanisms
2b. Media Access Control (MAC) Sublayer:
Node-to-node error control.
1. Physical:
Manages signalling to and from physical network connections.

Examples of devices/services:
Physical – Ethernet, Token Ring. A hub or repeater works here.
Data Link – Ethernet, ATM. A switch or bridge works here.
Network – ARP, RIP, IPv4, IPv6. A router works here.
Transport – TCP, UDP, SPX
Session – PPTP, H.245, NetBIOS, AppleTalk, WinSock
Presentation – JPEG, GIF, MPEG

References –

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s