1 Introduction

1 layering

networkingprotocols are normally developed in layers, with each layer responsible for adifferent facet of the communications.

Responsibility ofeach layer

  1) linklayer(data-link layer | network interface layer)

  includes:thedevice driver in the os and the corresponding network interface card in thecomputer.

  handle:allthe hardware details of physically interfacing with  the cable.

  2) networklayer(internet layer)

  handle:themovement of packets around the network

  3)transport layer

  handle:dataflow between two hosts

  4)application layer

  handle:thedetails of the particular application.

 

  twonetworks connected with a router

 

2 TCP/IP layering

  variousprotocols at the different layers in the TCP/IP protocol suite

 

TCP:provides areliable transport layer,even though the service it uses(IP) is unreliable.

UDP:sends andreceives datagrams for applications.

IP: the mainprotocol at the network layer which is used by both udp and tcp.

ICMP:used by IPlayer to exchange error messages and other vital information with the IP layerin another host or router.

IGMP:the internetgroup management protocol , used with multicasting.

ARP and RARP:usedby certain types of network interface to convert between the addresses used bythe IP layer and the addresses used by the network interface.

 

3 Internetaddresses

  Everyinterface on an internet must have a unique Internet address(IP address).

  Three typesof IP addresses:unicast, broadcast, multicast.

 

4 Encapsulation

 

 Encapsulation of data as it goes down the protocol stack

 

5 Client-Servermodel

steps foriterative server:

  1) wait fora client request to arrive

  2) processthe client request

  3) send theresponse back to the client that sent the request

  4) go backto step1

steps forconcurrent server:

  1) wait fora client request to arrive

  2) start anew server to handle this client's request.when complete, this new serverterminates.

  3) go backto 1

 

6 Port number

  the wellknown port numbers are contained in the file /etc/services

  commandexample:

   #cat /etc/services

   #grep  telnet /etc/services

 

7 RFCs

  All theofficial standards in the internet community are published as a Request forComment.Each RFC is identified by a number(the higher, the newer).

You can find theinformation needed here: http://www.rfc-editor.org/