CS 408 Computer Networks

        Protocols and the TCP/IP Protocol Suite  

Protocols.

•Cooperativeaction is necessary

• computer networking is not only to exchange  
• bytes 
• huge system with several utilities and functions.  
• For examples 
• error detection
• Encryption
• Routing
• etc.
• For proper communication, entities in different systems must speak the same language
• there must be mutually acceptable conventions and rules about the content, timing and underlying mechanisms

Those conventions and associated rules are referred as “PROTOCOLS” 

  Protocol Architecture

•Task of data transfer is broken up into some modules

—Why?

—How do these modules interact?

•For example, file transfer could use three modules

—File transfer application

—Communication service module

—Network access module

A Real World Example to Protocol Architecture philosopher-translator-secretary architecture.
 
Simplified File Transfer Architecture .

File Transfer Application Layer: Application specific commands, passwords and the actual file(s) – high level data

Communications Service Module: reliable transfer of those data – error detection, ordered delivery of data packets, etc.

Network Module: actual transfer of data and dealing with the network – if the network changes, only this module is affected, not the whole system.,

General protocol architecture principles that we have seen so far.

•Layered structure

  Protocol stack

•Each layer provides services to upper 

 layer; expect services from lower one

  Layer interfaces should be well-defined

•Peer entities communicate using their 

 own protocol

peer-to-peer protocols 
independent of protocols at other layers  
if one protocol changes, other protocol
should not get affected

Protocol Architectures and Networks.