lecture: networks and network management

MD 240MD 240TelecommunicationsTelecommunicationsand the Internetand the Internet

OverviewOverview

Background Telecommunications Concepts Network Technology Networked Computing Architectures Managing Networks

BackgroundBackground


Early Network Technologies 1791 – French develop “Optical Telegraph Network” …

uses cross-arms and pulleys for signals 1837 – Samuel Morse demonstrates the electric telegraph 1845 – Morse Magnetic Telegraph Company founded,

makes revenue of $413 in October U.S. Postmaster General declares that telegraph network will

never be profitable 1873 – Western Union holds assets of $40 Million 1886 – First telemarketing … Richard Sears sells

watches via telegraph

(Source: www.silkroad.com/net-history.html)

BackgroundBackgroundHistoryHistory

Early Network Technologies 1876 – Alexander Graham Bell invents phone 1879 – Phone service costs businesses $40/month 1902 – Marconi sends wireless signal across Atlantic 1930 – Telephone network outgrows telegraph network 1960s – Packet switching invented … proposed as basis

for ARPANET 1969 – First computer handshake takes place 1970 – 4 node ARPANET is born 1972 – First electronic mail message

(Source: www.silkroad.com/net-history.html)


Early Network Technologies 1984 – NSF builds 6 node NSFNET running at 56 kbps 1988 – U.S. Government mandates the OSI Protocol 1990 – ARPANET shuts down, having been superceded

by NSFNET (300,000 nodes and growing). NSFNET backbone upgraded to 1.5 Mbps

1990 – Internet services ARCHIE, GOPHER, and WAIS appear

1992 – Mosaic browser written, leading to development of Netscape Navigator … WWW is born

2003 – Affordable 802.11g Wi-Fi network devices communicate at 54Mbps

(Source: www.silkroad.com/net-history.html, http://www.computerhistory.org/exhibits/internet_history/index.page)


1990 Local Area Networks (LAN) come onto the scene

business case for LANs not obvious, most managers asking “What is a network?”

Wide Area Networks (WAN) a “strategic technology” … but only affordable for the largest corporations

Ex: DDB Needham built a new corporate headquarters in Chicago just so that they could have it fully wired and integrated into a new WAN

PC #180386

PC #280386Artisoft

Lantastic LANPeer-to-Peer

Basic File Sharing/Transfer(if you’re lucky) Printer Sharing

LaserPrinter


Today LAN -

Affordable network hardware ($50-$200/device) Cable Modem can affordably connect home/office network to

Internet and WWW (<$100/month)

WAN - most corporations, big and small, have access to the Internet T1 access < $1000/month, Digital Subscriber Line (DSL) even

less

BackgroundBackgroundSmall Office LANSmall Office LAN

TCP/IP FastEthernet Router

DSLModem

Windows NTClient

Windows 2000Application Server

4-portF.Eth. Hub

Linux FileServer for

Windows Network(Samba program)

Windows 95ClientB&W Laser

PrinterColor Laser

Printer

8-Port Fast Ethernet Switch

16-portEth. Switch

To ISP and WWW

USB Device

BackgroundBackgroundCorporate WANCorporate WAN

PBX Modem pool

router

host computer

San Francisco

Boston

BackgroundBackgroundFuture NetworkingFuture Networking

Internet 2 (www.internet2.org) Cooperative effort (in USA only) to develop next

generation of the Internet (NGI) Government Research Universities Industry

Internet 2 website reports on emerging network technologies and networked applications

BC is now an Internet 2 member org. (as of Dec. 2001) Efforts now being made to build a world-wide Internet2

network to allow academics to collaborate ABILENE – 10 Gbps network

Telecommunications ConceptsTelecommunications Concepts

Telecommunication ConceptsTelecommunication ConceptsDefinitionsDefinitions

Telecommunication long-distance communication through the use of

common carriers, including telephone, television, and radio.

Data Communications Electronic collection, exchange, and processing of data

or information, including text, pictures, voice, and other information that is digitally coded and intelligible to a variety of electronic machines

Telecommunication Concepts Telecommunication Concepts Electronic SignalsElectronic Signals

Analog Signals continuous waves that “carry” information by

altering the characteristics of the waves amplitude and frequency

Digital Signals discrete on-off pulses that convey information in

terms of 1s and 0s, just like the central processing unit in computers

Telecommunication ConceptsTelecommunication ConceptsMajor TaskMajor Task

DigitalInformation

AnalogInformation Translate analog

information intodigital informationwithout losing ordegrading anyinformation

Translate digitalinformation into

analog informationwithout losing or

degrading anyinformation

Examples …Modem: copper phone line (analog) into (digital) bits for fiber optic transmissionVideo/TV: VHS tape (analog) into (digital) MPEG for internet/satellite transmission

Network Technology Network Technology

Networking ProtocolsNetworking Protocols

Protocol A set of rules and procedures governing

transmission across a network Some protocols:

TCP/IP FTP SMTP http:// gopher://

Networking Software ProtocolsNetworking Software ProtocolsOpen Systems Interface (OSI) Reference ModelOpen Systems Interface (OSI) Reference Model

Physical Layer

Link Layer

Network Layer

Transport Layer

Session Layer

Presentation Layer

Application Layer User interface, file transfer, electronic mail programs

Data formatting and character code conversion

Negotiation and establishment of a connection between two computers (nodes)

Provision for end-to-end data delivery

User interface, routing of information packets across multiple networks

Transfer of units of information, error checking

Transmission of raw data over a communications channel

7

6

5

4

3

2

1Each layer depends on the layer below it.

FTPSMTPTelnet

TCPUDP

IP

IEEE 802X.25

Networking Software ProtocolsNetworking Software ProtocolsExample: ModemExample: Modem

HostComputer

HostComputer

PC orTerminal

PC orTerminal

MultiplexorMultiplexor

ModemModem

HostComputer

HostComputer

PC orTerminal

PC orTerminal

MultiplexorMultiplexor

ModemModem

Hardware

Front endprocessor

Receiver

Telecommunicationmedia

(channels)

OSI Layer 1

OSI Layer 2OSI Layer 3

OSI Layer 7

OSI Layer 6

OSI Layer 5OSI Layer 4

Networking Transmission ProtocolsNetworking Transmission ProtocolsBased Upon the OSI Reference ModelBased Upon the OSI Reference Model

NetBEUI Microsoft-only networks

IPX/SPX Novell Network, limited support, dying a slow death

AppleTalk Apple-only networks

TCP/IP Microsoft networking, Apple networking, UNIX/Linux

networking ... all support it

PPTP (Point-to-Point Tunneling Protocol) used for Virtual Private Networks; wraps around NetBEUI

DHCP (Dynamic Host Configuration Protocol) dynamically assigns IP addresses to computers on a TCP/IP LAN

Networking HardwareNetworking Hardware

Workstation computers Server computers/Mainframe computers Network interface cards (NICs) Inter-connection hardware Cabling

Unshielded twisted pair (UTP) cable Shielded twisted pair (STP) cable Coaxial cable Fiber-optic cable


Wide Area Network (WAN) A network that spans hundreds of feet to thousands of

miles Purpose is linking together other networks

A “network of networks”

Local Area Network (LAN) A network in which the devices are all fairly close to one

another The goal is to connect all of the devices

A “network of devices”

Networking HardwareNetworking Hardware Wide Area Network (WAN) Inter-Connection Hardware

Repeater a reamplification device, receives a message and passes it along

Bridge connects two networks together at OSI network layer 2 “dumb” … cannot translate messages from one protocol into another

Router an “intelligent” bridge, works at OSI network layer 3 understands network addresses where messages are going, and can route them to the computer

Gateway an “intelligent” router, works at OSI network layers 4-7 connects two different types of networks (e.g., AppleTalk and TCP/IP) translates data from one protocol into another (e.g., TCP/IP into AppleTalk) also provide “bridging” and “network layer routing” services

Dumb

Intelligent


Local Area Network (LAN) Inter-Connection Hardware Hub

passes messages between two computers by broadcasting packets to every computer on network

only one computer can talk at a time … potentially wastes network bandwidth

Switch an “intelligent” hub passes messages between two computers by creating a direct

connection between the two computers multiple computers can talk directly to each other at the same time …

makes better use of network bandwidth

Dumb

Intelligent

Network TopologyNetwork Topology

Topology The shape of a network; the network’s layout

Most Common Network Topologies Star Topology Ring Topology Bus Topology Mesh Topology Tree (Hybrid) Topology

Network TopologiesNetwork TopologiesStarStar

Stations linked to a central node, but each transmission is heard by all users (if host device is a hub)

HOSTHOST

USERUSER

USERUSER

USERUSERUSERUSER

Network TopologiesNetwork TopologiesRingRing

One way transmission, listen and re-transmit, common example is IBM’s Token Ring network

HOST

USER

USER

USER

Network TopologiesNetwork TopologiesBusBus

Stations linked to a central cable, easy to add new users

USER USER USER

USERUSER USER

terminatorterminator

Network TopologiesNetwork TopologiesMeshMesh

USER

USER

USER

USER

USER USER

Devices are connected with many redundant interconnections

Network TopologyNetwork Topology Which to Choose?

Depends Cost Reliability/failsafe requirements

Organizations mix and match, depending on the type of use

Ring: connects routers on a network Star: connects end users in a local workgroup

“Hybrid” Topology

“Tree” Topology

Network TechnologyNetwork TechnologyLayout and Implementation IssuesLayout and Implementation Issues

Distance (some media are limited) Range of services (data, voice, video) Security (encryption) Multiple access (capacity issues) Utilization (light vs. heavy use) Cost justifiable (per user) Installation (centralized) Allow for growth and expansion (people / equipment) Facilitate service and maintenance (upgrades)

Networks Make Possible ...Networks Make Possible ...Many ArchitecturesMany Architectures

Client/Server ArchitecturesClient/Server ArchitecturesSeparating Presentation, Application Logic, Separating Presentation, Application Logic, and Databaseand Database

PresentationLayer

ApplicationLogic

(Business Logic)

Layer

DatabaseLayer

TCP/IP TCP/IP

revenue = get_data()profit = revenue - cost income.report( profit, revenue)

acctid revenue

3443

6789 25

10,000

Computer #1 Computer #2 Computer #3

Client/Server ArchitecturesClient/Server ArchitecturesDistributing Presentation Logic, Distributing Presentation Logic, Application Logic, and Database MgmtApplication Logic, and Database Mgmt

Distributed Presentation Client: manages only a portion of presentation processing tasks Server: manages presentation, application, database

Remote Presentation Client: presentation logic Server: application logic and database management

Distributed Function Client: presentation logic and part of application Server: part of application and database management

Remote Data Management Client: presentation logic and application logic Server: database management

Distributed Data Management Client: manages presentation, application logic, and portion of database Server: manages part of database

More andmore ofpresentation,application, and database logic becomepositioned onclient

Internet TechnologyInternet Technology

HTML File-BasedHTML File-BasedWebsiteWebsite

Source: Philip and Alex’s Guide to Web Publishing, http://www.arsdigita.com/books/panda/


Website Built from Website Built from Common Gateway Common Gateway Interface (CGI) ProgramInterface (CGI) Program(2-Tier)(2-Tier)


Tier 1

Tier 2


CGI Program Requests CGI Program Requests Data from Database Data from Database (3-Tier)(3-Tier)


Tier 1

Tier 2

Tier 3


3-Tier Database-Backed3-Tier Database-BackedWebsiteWebsite


ScriptingLanguages

ASPJSP

CFMindex.asp

Internet Internet TechnologyTechnology

SecureSecure“N-Tier” Website “N-Tier” Website ArchitectureArchitecture


N-Tier ArchitectureN-Tier ArchitectureMSNBC.comMSNBC.com

WebServers

DatabaseServers

Internet TechnologyInternet TechnologyAn Enterprise-Wide NetworkAn Enterprise-Wide Network

Managing Enterprise NetworksManaging Enterprise Networks

Management ObjectivesManagement ObjectivesOpen Systems and Enterprise NetworkingOpen Systems and Enterprise Networking

Connectivity the ability of the various computer resources to communicate with each

other through network devices without human intervention

Portability the ability to move applications, data, and even people form one system

to another with minimal adjustments

Interoperability the ability of systems to work together by sharing applications, data, and

computer resources.

Scalability the ability to run applications unchanged on any open system where the

hardware can range form a laptop PC to a super computer

Managing Enterprise NetworksManaging Enterprise NetworksPresent TrendsPresent Trends

Enterprise Application Integration (EAI) Organizations have “legacy mainframe applications”

old systems and applications originating waaay back in time organizations have added ERP, CRM, etc., to these

Organizations already have built “enterprise network” to try to link desktops together

make the office worker’s desktop resources flexible Many other digital devices now used by enterprise

PDAs, Cash Registers, Laptops, Machines Now, integrating them through software that

“wraps” around a device and serves as an interface between that device and other “objects” in the enterprise that are allowed to communicate with it

Managing Enterprise NetworksManaging Enterprise NetworksIssues of ConcernIssues of Concern

Choose network design satisfactory for user needs Procure network components Tracking inventory of network hardware Network maintenance Network failure detection Billing customers (internal & external) who use the

network resources

Managing Enterprise NetworksManaging Enterprise NetworksTools for Managing NetworksTools for Managing Networks

Operations Support Systems (OSS) Network Planning Network Design Pre-Implementation Network Analysis

Visual Layout Tools Simulation of System Design

Network Management Inventory of computers, routers, hubs, etc., etc., Failure analysis OSS Customer Relationship Management

Managing Enterprise NetworksManaging Enterprise NetworksOperations Support SystemsOperations Support Systems

OSS PicturesOSS Pictures

Networking JobsNetworking Jobs

Network Engineer Average starting salary: $62,250-$87,000 Skill requirements:

Microsoft Certified Systems Engineer (MCSE) Cisco Certified Internet Expert (CCIE) Security related hardware and software experience LAN/WAN management and systems administration Background in Virtual Private Networks (VPNs), TCP/IP,

intrusion detection, firewall implementation Who’s hiring:

Financial services, government

(Vaas, L., “Networking Skills Still Crucial,” eWeek, Dec. 31, 2001, p. 33)

lecture: networks and network management

Documents

telephone network

homeoffice network

optical telegraph network

telegraph source

g wifi network devices

electric telegraph

node arpanet

mbps source