NETWORKING BASICS

• Network – Connection of Computers

• Ethernet uses only one cable that is used to connect all over the world – RJ45/CAT 5/CAT 6/10 baset. Earlier Token ring was used in Ethernet.

• Types
1. Broadcast Multi-Access: All systems are connected to the network and only the addressed system receives the packets. First messages are broadcasted, addresses are received and then the packets are unicasted.
2. Point-to-point: Only two computers are connected. Address is not mandatory (But is present).It is not broadcasted.

·         Routers: Router is an intelligent device that receives data (packet) and checks from where it comes and where it goes (in the best route).Router is a CISCO product.

Note: CCNA tells about

ü  How to connect computers?

ü  How hosts systems talks to each other, when and why?

ü  How it interacts with the router and how router talks to the outer world?

·         Networks are divided as the private (illegal, reserved, non-routable) and public (Legal) networks. The private networks are secured leased lines that are over a particular area-used internally only. The public networks are world wide. 

·         Computers will have two addresses:

1.      Logical Address – IP Address

2.      Physical Address – Hardware address

                                  -- MAC address

                                  -- Ethernet address

                                  -- Permanent address

·         MAC Address – Media Access Control Address. No two network cards will have the same MAC addresses.

            E.g.:  0010ab 1234cd

                           Vendor    Card No.

                            Code

·         Operating System: OS interfaces between the hardware and the software. The software program that binds itself to the machine components

·         We need a protocol to transfer data between two systems else your system will be a stand-alone system. In order for two systems to communicate NOS (Network Operating Systems) is needed.

·         TCP/IP is used to transfer data between systems. It is not a single protocol instead it is a stack of protocols.