- Physical layer:
Amount of volts needed to represent 0 or 1.
Type of transmission medium whether Guided or Unguided
Guided(copper wire, fiber optics) and Unguided(laser or radio waves).
- Data link layer
it also performs flow control.
Node to Node transmission takes place.
ARP(Address Resolution Protocol),RARP(Reverse Address Resolution Protocol),
Frame relay(x.25),ISDN,PPP,LLC etc.
- Network layer
This layer mainly adds source and destination address in the header.
Route the data to different LANs and WANs depending on network Address.
Example : IP,ICMP.
- Transport layer
This ensures the transmission of data to the correct process.
TCP and UDP packets comes under this.
- Session Layer
This checks two stations do not attempt the same operation at same time.
Critical operation functionality also present here(synchronization).
Starts and stops session and maintains order.
- Presentation layer
It encode data in a format so that receiver can easily understand.
This layer also deals with the encryption and compression of the data.
eg: ASCII to EBCDID , Binary to BCD.
- Application layer
Examples are : SMPT/IMAP4(E-MAIL),Telenet,HTTP(WWW),FTP(File Transfer),
RIP(Route Information Protocol),OSPF(Open Shortest Path First),TFTP (Trivial File Transfer Protocol),DHCP(Dynamic Host Configuration Protocol),BOOTP(Bootstrap protocol).
Names of various PDU in each layer.
Application Protocol: APDU
Network : Packet