Layers

TCP/IP Layers

From bottom to top, they are:

  1. link layer

    It uses MAC address to identify the devices in the network.

    The unit of data in this layer is frame.

  2. internet layer

    It uses IP address instead of MAC address. It connects the small networks into big one.

    The unit of data in this layer is packet.

  3. transport layer

    It makes transportation work. TCP is on this layer.

    The unit of data in this layer is segment.

  4. application layer

    HTTP is on this layer. There are other protocals, such as Telnet、SSH、FTP、SMTP.

    The unit of data in this layer is message.

OSI (Open System Interconnection Reference Model)

There are 7 layers.

  1. Physical

  2. Data Link

  3. Network

  4. Transport

  5. Session

  6. Presentation

  7. Application

osi

We can map OSI layers and TCP/IP layers.

OSI | TCP/IP --- | --- Physical | Data Link | link layer Network | internet layer Transport | transport layer Session, Presentatio, Application | application layer

osi-tcpip