Monday, 11 February 2013

NETWORKING

NETWORKING
Basic Networking
Network-A group of interconnected computers that share resources and information.
Connected computers sharing resources is referred to as networking
Stand-Alone- Computers not connected to a network
Comparing Peer to Peer vs. Client-Server
Client - a workstation used to request services from a dedicated server or another client
Server- provides services to requestor a dedicated server is recommended for 10 clients or more computers
Peer to Peer- Networked Computers that both requests and provides network services

Peer to Peer implementations:
(use to network 10 or less computers)


Advantages:
Lower Cost, Easy to setup and good for temporary network setup
Disadvantages:
Limited growth, No central location, Weak Security, To many passwords
Server Based implementations: (use to network 10 or more computers)
Advantages:
Centralized management, Strong Security, Expansion and Create redundant systems
Disadvantages:
Expensive, difficult to implement and Central Point of failure
Comparing Servers

Non Dedicated Server vs. Dedicated Server
File Server-offers services that allow users to share files Includes storing, retrieving, and moving data
Print Servers-The print server controls the queue or spooler, which hold jobs till ready
Application Servers- Allows client to access and use extra computing power and extensive software applications that reside on a shared computer SQL backend does all the processing

Other Servers - Database, Proxy Servers, Mail, FTP, DNS, DHCP, RAS, Web, Directory and Newsgroup
Workgroup vs. Domain
Workgroup model, every computer in the network has equal access to one another and is responsible and maintains its own set of users and passwords.
Domain model maintains a single database of user logins for the entire network

Comparing Share-Level Security vs. User-Level Security
Peer to Peer use share level security to assign resources not as safe (password base)

Client Server use user level security Admin gives rights before anyone can access PC (permission base)

Types of Networks
LAN - Local Area Network a group of computers connected within a building or a campus (Example of LAN may consist of computers located on a single floor or a building or it might link all the computers in a small company.
WAN - A network consisting of computers of LAN's connected across a distance WAN can cover small to large distances, using different topologies such as telephone lines, fiber optic cabling, satellite transmissions and microwave transmissions.

MAN - A network of LAN's that covers a city or large campus environment


PAN - Personal Area Network

Other types of networks

CAN - Campus Area Network
WLAN - Wireless LAN

GAN - Global Area Network
SAN - Storage Area Network
What hardware components do we need in order to network computers?

All networks share common elements, including:

We need computers
or or
Questions to ask before we network?

Will the computer be used as a client or a server?
What specifications will we need to setup a network?

CPU: Pentium IV or AMD Athlon
Memory: SDRAM or RDRAM
Hard Drive Capacity: 50-150GB
We need resources, files and applications to share
We can share printers, scanners and programs such as MS Office Applications.

We need network cards

Things to look for when buying a network card

Bus: PCI, PCI-X, PCIe, ISA, CNR, PCMCIA, Express Card, USB, Firewire or integrated
Connector: RJ45, USB, Firewire, BNC, Wireless or Fiber Optic Ports (ST/SC/MTRJ/LC)
Manufacturer: Intel, 3COM or Netgear (issues with drivers)
Speed
: 10, 100 or 1000Mbps (Standard Ethernet, Fast Ethernet and Gigabit Ethernet)
Access Method: CSMA/CD and CSMA/CA


BNC RJ45 SC
Manufacturer: Intel, NetGear, DLink, Linksys, Real Tek (issues with drivers)

Each NIC card has a unique ID called the MAC (Media Access Control) Address or Physical Address (48bits)
First 3 Positions identifies the Manufacturer ID and the last 3 Positions identifies the NIC Card ID
00 – A0 – 00 – BB – E1 – 8F - FF
to view the NIC's MAC address (START>RUN>CMD>IPCONFIG /ALL) or WINIPCFG (9x) from the run menu

NIC cards must implement a standard signaling methodology to gains access to a network.
Access Method: How a network device will communicate with one another

CSMA/CD
CS (Carrier Sense) Before transmitting, listen for signal; if none is found, it is the OK to transmit
MA (Multiple Access) All computers share the same media and signaling techniques.
CD (Collision Detection) Detect collisions, wait and retransmit
CSMA/CA
CS (Carrier Sense) Before transmitting, listen for signal; if none is found, it is the OK to transmit
MA (Multiple Access) All computers share the same media and signaling techniques.
CD (Collision Avoidance) Avoid collisions, wait and retransmit
Token Passing - Token is passed sequentially to each computer on the network based on a NIC's ID.

Baseband vs. Broadband

Broadband transmissions enable two or more communication channels to share the bandwidth of the transmission media. Broadband networks can simultaneously accommodate video, voice and data. Most DSL and Cable modem providers use broadband communications.

Baseband transmissions enable digitals signals over a single frequency. With baseband transmission, the entire communication channel capacity is used to transmit a single date signal. Most LAN’s today use baseband technology.

Multiplexing divides a transmission facility into two or more channels. The two main ways to share a channel are time division multiplexing and frequency division multiplex.

Full Duplex vs. Half Duplex communication

Full Duplex is a type of communication which can send data both directions simultaneously. For example, on a full duplex network one workstation can be sending data while another is receiving data at the same time.

Half Duplex is a type of communication which can send data both directions, but not at the same time. For example, a workstation can send data and then immediately receive data, but cannot transmit and receive simultaneously.
Crossover cables
Packets vs. Frames

What are frames?

A frame can be defined as the unit of data transferred across the network, defined at the data link (network access) layer of the protocol stack.
NIC card sends data in discrete chunks called frames (and has the following typical information)
Preamble
Recepient's MAC address
Sender's MAC address
Length
Data
Pad
CRC

Preamble – All Ethernet Frames begin with a Preamble 64bit series of 1’s and 0’s This is the start of a frame

MAC Address – Media Access Control a Unique ID of a NIC card 48bits (Recipient and Sender)
Length – An Ethernet Frame carry up to 1500 bytes of data in a single frame

Data – Information Data of what the frame carries

Pad – Will add extra data if not 64 bytes in size

CRC-Cyclic Redundancy Check is used for correction

Within the frames are information called packets

What are packets?


A packet can be defined as the unit of data at any layer of the protocol stack, prior to, or after transmission
Packets contains the following information
Data Type Packet Count Recipient’s IP address Sender's IP address Data
Packets contains the following information
Data Type Packet Count Recepient's IP address Sender's IP address Data

 





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