MD 240MD 240TelecommunicationsTelecommunicationsand the Internetand the Internet
OverviewOverview
Background Telecommunications Concepts Network Technology Networked Computing Architectures Managing Networks
BackgroundBackground
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)
BackgroundBackgroundHistoryHistory
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node NSFNET running at 56 kbps 1988 – U.S. Government mandates the OSI Protocol 1990 – ARPANET shuts down, having been superceded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)
BackgroundBackgroundHistoryHistory
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
BackgroundBackground
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
Networking HardwareNetworking Hardware
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
Networking HardwareNetworking Hardware
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/
Internet TechnologyInternet Technology
Website Built from Website Built from Common Gateway Common Gateway Interface (CGI) ProgramInterface (CGI) Program(2-Tier)(2-Tier)
Source: Philip and Alex’s Guide to Web Publishing, http://www.arsdigita.com/books/panda/
Tier 1
Tier 2
Internet TechnologyInternet Technology
CGI Program Requests CGI Program Requests Data from Database Data from Database (3-Tier)(3-Tier)
Source: Philip and Alex’s Guide to Web Publishing, http://www.arsdigita.com/books/panda/
Tier 1
Tier 2
Tier 3
Internet TechnologyInternet Technology
3-Tier Database-Backed3-Tier Database-BackedWebsiteWebsite
Source: Philip and Alex’s Guide to Web Publishing, http://www.arsdigita.com/books/panda/
ScriptingLanguages
ASPJSP
CFMindex.asp
Internet Internet TechnologyTechnology
SecureSecure“N-Tier” Website “N-Tier” Website ArchitectureArchitecture
Source: Philip and Alex’s Guide to Web Publishing, http://www.arsdigita.com/books/panda/
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)