Basics of computer Networking

There is no need to say what is computer networking, and what the use of it, all of you will be familiar with that all, so we are not discussing that topics, but just highlighting the basic terms related to computer networking,

1. Different topologies :- Mesh, Ring, Star, Bus
2. OSI Layers :- Physical, Data link, Network, Transport, Session, Presentation, Application
3. Data link sub layers :- MAC (Media Access Control) and LLC (Logical Link Control)
4. IP Address :- Unique 32bit (IPv4)/128bit (IPv6) number assigned to the devices in a network (Including Routers,Switches,Computers etc)
5. Different networking and inter networking protocols :- TCP, UDP, ARP, RARP, ICMP, IGMP, DHCP etc
6. Port numbers :- Port numbers like 80 for http, 21 -ftp, 22 -SSH, 23- Telnet etc
7. MAC Address :- 48bit Physical Address (Unique)
8. Networking and Inter networking devices :- Routers, Hub, Switches, Bridges etc
9. Concept of Routing protocols, Gateways etc
10. Concept of net id, host id, network address, sub netting, super netting, subnet Mask, simplex, half duplex and full duplex modes of communication

There are more terms related to networking, and we are not going through that all, and will discuss whenever necessary in future discussions.

The ip address is unique for the system in a network. An ip address has 2 parts, a network portion and a host portion. Network portion defines in which network that address belongs to; where as the host portion determine the position of that ip within that particular network.The subnet mask has the role of dividing the ip address in to network portion and host portion.

Cabling

the two ends of 8 color wires of Ethernet cable are connected in 3 different ways to for 3 types of cables as below,

Straight through

Orange white - Orange White

Orange - Orange

Green white - Green white

Blue - Blue

Blue white - Blue white

Green - Green

Brown white - Brown white

Brown - Brown

The straight through cables are used to connect dissimilar devices like PC and Hub, PC and Switch etc.

Cross over cable

Orange white - Green white

Orange - Green

Green white - Orange white

Blue - Blue

Blue white - Blue white

Green - Orange

Brown white - Brown white

Brown - Brown

Cross over cables are used to connect similar devices like hub to hub, PC to PC switch to switch etc.

Rolled or Roll over cable

Orange white - Brown

Orange - Brown white

Green white - Green

Blue - Blue white

Blue white - Blue

Green - Green white

Brown white - Orange

Brown - Orange white