Thursday 23 June 2011

What is Network?

Network
Connection of two or more nodes over the physical media is called as Network.

Networking
Connection of two or more nodes over the physical media and sharing the resources is called as Networking.

Types of Network:

1.Peer-to-Peer Network
Peer meaning client, Operating system used as client are win95, 98,NT4.0 Workstation, Win2000 prof, ME, XP prof.
Workgroup is a small group of computers where no centralized administration and no security is provided.

2.Server based Networks
Server is the one that serves the resources to clients.
Client is the one that requests for the resources from server.
Non-dedicated Server is the system that works both as client and server.

Operating system used as server is WinNT 3.51, 4.0, Win2000server, Win2003server.
Domain
Logical group of computers where centralized administration and security is concerned.

Further types of network:

PAN – Personalized Area Network
LAN – Local Area Network
CAN – Campus Area Network or BAN – Branch Area Network (within 2km diameter using FDDI)
SAN – Storage Area Network
MAN – Metropolitan Area Network (takes support of PSTN)
WAN – Wide Area Network (takes support of X.25, Frame-relay, ATM, Internet, ISDN)
SoAN – Solaris Area Network (network using satellite)
WIRELESS
INTERNET
EXTRANET – Connection between different branches
INTRANET – Connection within the branches

LAN Requirements for Networking:
Server, Client, NIC, Cable (Media), Switch, Topology, Protocol, Services.

Media:
There are 2 types of media
1.Guided media (wired media)                 2.UnGuided media (wireless media)

1.Guided media (wired media)
e.g. Co-axial cable, twisted pair cable, fibre optics cable

Co-axial cable
1.Maximum Distance 500mts
2.Low response
3.Less attenuation
4.Speed 10Mbps
5.Communication done is half duplex
6.Connection done using BNC – Bayonet Neil Concellmen Connector
7.Registered Guage Standard (RG)
            RG 9,11,12                   Thinnet Coaxial Cable
            RG 58                           Thicknet Coaxial Cable
            RG 58/U, RG 58A/U      Military Network
            RG 59                           Dish Network
            RG 62                           Arc Net
           
Thicknet also called as 10base5 where 10 – Bandwidth base – Baseband and 5 – 500mts
Thinnet also called as 10base2 where 10 – Bandwidth base – Baseband and 2 – 200mts

Twisted pair cable
1.Maximum Distance 100mts
2.Speed 10/100/1000Mbps
3.Communication done is half / full duplex
4.Connection done using RJ45 Connector

10baseT            Supports 10Mbps
10baseTx          Supports 10 or 100 Mbps
100baseT          Supports 100Mbps
1000baseTx      Supports 1Gbps

4 pairs of wires, orange – tip       orange/white – tap.

All orange/white, green/white, blue/white, brown/white provides grounding to the orange, green, blue, brown wires.

Types of Twisted pair cable
1.Unshielded Twisted Pair Cable (UTP)               2.Shielded Twisted Pair Cable (STP)

Categories of Twisted pair cables
            CAT1                            Telephone Networks (4Mbps)
            CAT2                            Small Computer Networks, Telephone Networks (4Mbps)
            CAT3                            LAN – Ethernet (16Mbps)
            CAT4                            Token Ring Network (40Mbps)
            CAT5                            LAN – Fast Ethernet (100Mbps)
            CAT5e & CAT6             LAN – Fast Ethernet (1Gbps / 1000Mbps)
Registered Jack (RJ Connectors)
            RJ11                            Telephones
            RJ12                            Telephone Network, Modems, Small Networks
            RJ45                            Local Area Network
Optical Fibre Cable
1.Maximum Distance 3 to 10 Kms
2.No EMI – Electro Magnetic Interference
3.Speed 100Mbps or Higher
4.Connectors used are ST – Straight Trip and SC – Subscriber Connectors
5.Two modes of communication Single mode (single beam) and Multiple mode (multiple beam)


2.UnGuided media (wireless media)
e.g. infrared, microwaves, radio waves
Infrared
1.Introduced in 1985
2.Point-to-Point communication (distance between 2 computers should not be more than 15mts)
3.Multipoint communication (distance between 2 computers should not be more than 30 mts)
4.Maximum Bandwidth 11Mbps

Microwaves
1.Electromagnetic Waves > 1Mhz

Radio Waves
1.Introduced in 1998 for computers
2.Electromagnetic Waves < 1Mhz
3.Maximum frequency available now is 2Ghz

Protocols
A set of rules for a particular type of communication.

Two types of Protocols
1.Connection Oriented                2.Connectionless Oriented

Connection Oriented
1.Follows the same path for data transfer
2.Acknowledgement
3.Reliable
4.e.g. TCP, SPX, AppleTalk datagram protocol

Connectionless Oriented
1.Follows the path where less traffic is found
2.No Acknowledgement
3.Non-Reliable
4.e.g. IP, IPX, UDP, AppleTalk protocol

Standards
Two types of Standards
1.Defacto Standard                    2.Dejuire Standard


Defacto Standard
Standard widely used by all is called as Defacto Standard.

Dejuire Standard
Standard defined by an organization is called as Dejuire Standard.

Standard Organizations / Committees

IEEE – Institute of Electrical and Electronics Engineers
IANA – International Assigned Number Authority
ISO – International Standards Organization
ITU-T – International Telecommunication Union – Telecommunication Standardization Sector
EIA / TIA – Electronics Industry Association / Telecommunication Industry Association
ANSI – American National Standards Institute

Network Segmentation
Breaking up a larger network into a number of smaller ones is called as Network Segmentation and is accomplished using Routers, Switches and Bridges.

Causes of LAN Traffic congestion
1.Too many hosts in a broadcast domain
2.Broadcast storms
3.Multicasting
4.Low Bandwidth
5.Adding Hubs for connectivity to the network
6.A large amount of ARP and IPX Traffic.

Broadcast Domain
A group of devices receiving broadcast frames initiating from any device within the group.

Collision Domain
The network area in Ethernet over, which frames that have collided and damaged.

Broadcast Storms
An undesired event on the network caused by the simultaneous transmission of any number of broadcasts across the network.

Multicasting
Any communication between a single sender and multiple receivers.

ARP
Address Resolution Protocol, the protocol that traces IP addresses to MAC addresses.

IPX
Internetwork Packet Exchange, layer 3 protocol used in Novell Netware networks for transferring information from servers to workstations.

Router
It’s a layer 3 device that connects 2 different networks and routes packets of data from one network to another. It breaks up Broadcast domain as well as Collision Domain.

Advantages of Router
1.Router don’t forward Broadcasts by default.
2.Perform access control on the traffic that flows through the router i.e. Packet Filtering.
3.Network Address Translation.
4.Quality of Service for particular network traffic.
5.Can be used as a DHCP relay agent.
7.Connects different VLAN’s.

DCE-Data Communications Equipment
The DCE supplies the physical connection to the network, forwards traffic, and provides a clocking signal to synchronize data transmission between DTE and DCE devices.

DTE-Data Terminal Equipment
Any device located at the end user i.e. network interface serving as a destination or source or both. DTE includes devices such as Multiplexers, routers, protocol translators and computers.

Different Modes for configuring a router
1.User Mode- some basic commands like ping, telnet can be done. Prompt will be Router >
2.Execution or Privilege or Enable Mode- can view all configuration details, minimal commands like ping, telnet, and clock setting. Prompt will be Router #
3.Global Configuration Mode- where all configurations are done. Prompt will be Router(config)#

Sub Configuration Modes
1.Interface configuration mode, prompt will be Router(config-if)#
2.Router configuration mode, prompt will be Router(config-router)#
3.Line configuration mode, prompt will be Router(config-line)#

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