Networks

1st week

Understanding the network systems and networks:

Network concepts Cable Network devices Network Topologies

What Is Networking? Involves connecting computers for the

purpose of sharing information and resources Requires a great deal of technology Offers many possible choices for physical

connections and related software

Networking Fundamentals Consists of two or more computers

connected to each other by wire or cable to transmit data back and forth

Primary motivation arises from a need for individuals to share data quickly and efficiently

Primary Benefits of Networking Permits groups of users to exchange information

routinely and to route data from one individual to another Single consistent master copy of data files

Improves human communication using network services Electronic mail (e-mail)

Enables network device, database & source sharing Fund saving Group working

Network - Why?

Office Representativeat Vietnam

Headquartersat USA Office at

China

Network - Why?

Local and Wide Area Networks LAN

A collection of computers and other networked devices that fit within the scope of a single physical network

Provides the building blocks for internetworks and WANs Distance: ~ km Speed: 100 Mbps

WAN An internetwork that spans distances measured in miles Links together two or more separate LANs

from simple LAN

Hub

Computer

Laptop

Printer

MinicomputerWorkstation

Computer Computer

Server

PC1 PC2 PC3

PC4

PC5

Hub/Switch

Printer

to WAN,

Workstation

Workstation

Workstation

Workstation

Workstation

Workstation

Workstation

Router

Saigonng Nai

H Ni

Internet

64 Kbps

Internet

, and Internet !!!

VN

AUFR

TCP/IP (Transmission Control Protocol/Internet Protocol)

A Networking Terminologies Clients, peers, and servers Network medium and network messages Network protocols Network software Network services

Clients, Peers, and Servers Server

A computer that shares its resources across the network

Responds to client requests for information by providing the requested information

Client A computer that accesses shared resources Requests information

The Client/Server Relationship

Clients, Peers, and Servers Client/server network

Certain computers take specialized roles and function mostly as servers

Ordinary users machines tend to function mostly as clients

Web, Ftp, Mail servers

Peer-to-peer network Each computer can be a client to other

computers and act as a server as well

The Network Medium Carries Network Messages Network medium

Usually refers to the cable (metallic or fiber-optic) that links computers on a network

Can also describe wireless networking To access any network, computers must attach to

the network medium with a physical interface Network interface card (NIC) Network adapter

Network Protocols Sets of rules for communicating across a

network Examples

TCP/IP (SMTP, POP3, HTTP ) NetBEUI IPX/SPX NWLink

Network Software Issues requests and responses that let

computers take the roles of clients and servers

Network operating system (NOS) Specialized collection of software that gives a

computer the ability to communicate over a network and to take advantage of networking services

Network Services Reside primarily on servers Can include file and print services, file-

sharing, e-mail and other messaging services

Network Models

OSI vs TCP/IP

The Layered Nature of Networked Communications

Cable

Fiber

UTP v RJ-45 jackCoaxial cable

http://nyimage.attenza.com/images/tutorials/TOPIC_26124/50547.jpghttp://images.google.com/imgres?imgurl=www.kiu.ad.jp/act/mini/cable-rj45.gif&imgrefurl=http://www.kiu.ad.jp/act/mini/cable.html&h=282&w=499&prev=/images%3Fq%3DUTP%2Bcable%26start%3D60%26svnum%3D10%26hl%3Den%26lr%3D%26ie%3DUTF-8%26sa%3DN

Cables Twisted pair

Unshielded Twisted Pair (UTP) Shielded Twisted Pair (STP)

Data to 100 MbpsC5

Data to 20 Mbps (16 Mbps for Token ring)C4

Data to 10 Mbps (Ethernet)C3

Data to 4 MbpsC2

Voice only (telephone wire)C1

PurposeType

Twisted pair Cable

Cables Coaxial Cable

used normally in cable television or networks. has a better performance than the twisted pair. Bandwidth: ~ 10 Mbps

Thinnet (10Base2) Thicknet (10Base5)

Thinnet connects directly to the network card. Thicknet can be used to connect Thinnet networks. A transceiver is used to connect the 2 cable types.

Coaxial Cable

Cables Fiber optic cable (10BaseF)

These utilized glass or plastic threads to and modulated light waves to carry the signal.

Bandwidth: ~ 2Gbps Distance: ~ km Consumed signal on cable: low

2000Fiber Optic10BaseF500Thick coaxial10Base5185Thin coaxial10Base2

100Unshielded Twisted pair10BaseT

Maximum length (m)Type of cableName

Fiber optic cable

Ethernet Cable Standards Ethernet

10Base-T (100m, Unshielded Twisted Pair = UTP) 10Base-2 (~200m, Coax) 10Base-5 (500m, Coax) 10Base-FL (2000m=2km, Multimode Fiber)

Fast Ethernet 100Base-TX (100m over CAT5 UTP) 100Base-FX (2000m=2km over MM Fiber)

Gigabit Ethernet 1000Base-SX (300m over MM Fiber) 1000Base-LX (550m over MM Fiber, 3000m over

SM Fiber)

Types of network devices NIC Network Interface Card

Types of network devices Repeater:

Layer 1 Physical ~ 100m 2 ports : 1 in, 1 out

Hub Multi-port Repeater

Hubs

Active Hubs Regenerate the signals as they receive them

and send them along Generally have many ports; sometimes called

multiport repeaters Require electrical power to run

Passive Hubs Simply a central connection point Signal passes through the hub without any

amplification or regeneration Require no power

Hybrid Hubs Interconnect different types of cables Maximize a networks efficiency

Intelligent Hub, switch Hub

Types of network devicesBridge:

Forward or receive frame based on MAC address. Used to connect 2 or more networks with the same

protocol. Learning bridge

(auto update)

Switch Switch (Layer 2 - Data Link) : multi-port

Bridge

Router Router (Layer 3 Network)

Router Routers operate at the network layer, connecting two or more

network segments that may different data link layer protocols, but the same network layer protocol.

They can also connect different types of cable. Another important router feature is that they choose the best

route for a packet to follow, hence the name router. This also means that routers need to perform more processing

than bridges or layer 2 switches. Another important difference is that, unlike a bridge, a router only

processes messages that are specifically addressed to it.

Example of Router

Gateway Like routers, gateways also operate at the

network layer, but they are more complex than routers because they provide an interface between more dissimilar networks.

Like routers, gateways only process messages that are specifically addressed to them.

Some gateways operate at the application layer as well.

Example of Gateway

Network Topologies Bus

http://stmail.fju.edu.tw/~b8610041/images/network_img/bus.jpghttp://www22.verizon.com/about/community/learningcenter/articles/images/hsw_HowLanSwtchWk/lan-switch-bus.jpg

Network Topologies Star

http://stmail.fju.edu.tw/~b8610041/images/network_img/star.jpghttp://www22.verizon.com/about/community/learningcenter/articles/images/hsw_HowLanSwtchWk/lan-switch-star.jpg

Network Topologies Ring

http://www22.verizon.com/about/community/learningcenter/articles/images/hsw_HowLanSwtchWk/lan-switch-ring.jpghttp://www.networkthaionline.com/technology/network1/images/network13.gif

Network Architectures Peer-to-peer Server-based Storage-area Hybrid

Peer-to-peer Networking Any computer can function as either a client

or a server No one computer has any higher priority to

access, or heightened responsibility to provide, shared resources on the network

Every user must act as a system administrator

Typical Peer-to-peer Network

Server-based Networks Users act as clients of dedicated machines

that take the server role

Typical Server-based Network

Storage-area Networks (SANs) Centralized network storage Data transfer occurs over high-speed links for

faster access Appropriate for largest-scale networks

Typical SAN

Hybrid Networks Incorporates both peer-to-peer and server-

based features Sometimes called combination networks

Specialized Servers Application servers Communication servers Domain controllers/directory servers Fax servers File and print servers Mail servers Web servers

Application Servers Supply the server side of client/server

applications, and often the data that goes along with them, to network clients

Communication Servers Provide access to network resources for

users not directly attached to the network (inbound communications)

Permit network users to access external resources not directly attached to the network (outbound communications)

Domain Controllers/Directory Servers Handle the logon services and manage the

collection of computers, users, and so on in a domain

Fax Servers Manage fax traffic for a network

Receive incoming faxes from phone lines and direct them to users across the network

Collect outgoing faxes across the network before sending them over a phone line

Typically use one or more fax modem interfaces

File and Print Servers Most common type of network servers Provide basic networked file storage and

retrieval services and access to networked printers

Let users run applications locally but keep their data files on the server

Mail Servers Manage the flow of e-mail messages for

network users Commonly provide store-and-forward

services

Web Servers The combination of hardware and software

that stores information that is accessible over the Internet via the World Wide Web (WWW)

Selecting the Right Type of Network Budget Number of users Types of applications or network services Requirements for centralized administration

and control

Homework (Group 1)1. Advantages & Disadvantages

a) Peer-to-peer Networkingb) Server-based Networkingc) Storage-area Networking

2. When do choose aa) Peer-to-Peer Networkb) Server-based Network

3. Difference between Repeater, Hub, Bridge, Router and Gateway