Introduction to network

TCP/IP

 

	TCP	UDP
Reliable	O	X
Flow control	O	X
Congestion control	O	X

 

Then, when is UDP used?

 

: When don't need to be reliable. When we don't need to pay attention in leaking some packet.  (ex, voice talk)

 

* Protocal : Coordinated rule in network communication.

 

Data switching policy

 

   - circuit switching : End to End "reserved" for call

 

   - packet switching : Data are sent as packets.

 

Circuit switching method is restricted to number of clients. So, most network are using packet switching method.

 

Packet switching 

 

   - Too many input to output size or rate => Use buffer or Queue.

 

Router (packet switching)

   - Four major delay in data swtiching 

 

   Processing delay : 패킷을 검사하여 오류 여부와 목적지를 결정하는데 걸리는 지연.  

   

   Queueing delay : 패킷이 출력 버퍼에서 대기에 걸리는 지연.

 

   Transmission delay : 데이터가 나갈때 데이터 시작부터 끝까지 출력 처리되는데 걸리는 지연.

 

   Propagation delay : transmission 이후 다음 라우터까지 도달하는데 걸리는 시간. 

   

Packet loss

 

   Overflow of queue => "packet loss"

 

  ** tcp reliablity re-send again, from the begin!

 

 

Note