OSI and TCP-IP Network Models
Just a note for myself to remember about OSI 7 Layers and TCP/IP.
OSI 7 Layers
Layer # |
Name |
Mnemonic |
Encapsulation Units |
Devices or Components |
Keywords/Description |
7 |
Application |
All |
data |
PC |
Network services for application processes, such as file, print, messaging, database services |
6 |
Presentation |
People |
data |
|
Standard interface to data for the application layer. MIME encoding, data encryption, conversion, formatting, compression |
5 |
Session |
Seem |
data |
|
Interhost communication. Establishes, manages and terminates connection between applications |
4 |
Transport |
To |
segments |
|
End-to-end connections and reliability. Segmentation/desegmentation of data in proper sequence. Flow control |
3 |
Network |
Need |
packets |
router |
Logical addressing and path determination. Routing. Reporting delivery errors |
2 |
Data Link |
Data |
frames |
bridge, switch, NIC |
Physical addressing and access to media. Two sublayers: Logical Link Control (LLC) and Media Access Control (MAC) |
1 |
Physical |
Processing |
bits |
repeater, hub, transciever |
Binary transmission signals and encoding. Layout of pins, voltages, cable specifications, modulation |
OSI comparision with TCP/IP Protocol Stack
OSI # |
OSI Layer Name |
TCP/IP # |
TCP/IP Layer Name |
Encapsulation Units |
TCP/IP Protocols |
7 |
Application |
4 |
Application |
data |
FTP, HTTP, POP3, IMAP, telnet, SMTP, DNS, TFTP |
6 |
Presentation |
data |
|
5 |
Session |
data |
|
4 |
Transport |
3 |
Transport |
segments |
TCP, UDP |
3 |
Network |
2 |
Internet |
packets |
IP |
2 |
Data Link |
1 |
Network Access |
frames |
|
1 |
Physical |
bits |
|