Infrastructure Framework  «Prev  Next»

OSI Network Components

OSI network model and network Components

  1. Application
  2. Presentation
  3. Session
  4. Transport
  5. Network
  6. Data Link
  7. Physical

Layered Protocols

  1. Protocols connect entities on same level, within the layer
  2. Higher layers use services provided by lower layers
  3. Layers are independent and defined by interface provided to the higher layer and required from the lower layer

1) Entity provides an interface 2) Entity uses an interface

Entities communicate by exchanging Protocol Data Units (PDUs) with entities on the same level

Why Layers

  1. Layers may be exchanged as long as interfaces stay unchanged
    a) WWW was built on top of existing TCP/IP implementations, b) WWW does not have to care about the media (modem, Ethernet, radio link etc.),
    c) ATM can be used to transport IP packets without any changes to applications, d)IPv6 will replace the entire IP part of the TCP/IP layer
  2. Layering makes development easier and adds flexibility