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Agenda

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Title: Agenda


1
Agenda
  • Go over the projects
  • Review communication tasks
  • Review network design issues
  • Discuss application architecture
  • Discuss the internet, www, email

2
Projects
  • Design a wireless network
  • Design a telecommuting policy
  • Research voice over IP
  • Research home Wi-fi and security

3
Design a wireless network for UCCS
  • 5 Vendor products
  • Cost, contact information, pros/cons
  • Pros/cons of wireless infrastructure
  • Capabilities of todays wireless products
  • 802.11a, 802.11b, 802.11g (WiFi)
  • I should be able to (intelligently) pick a
    product, calculate the cost and contact a vendor

4
Telecommuting policy
  • Define telecommuting
  • Outline what equipment is needed
  • Cover who is eligible for this plan
  • Cover the costs, risks and benefits

5
Voice over IP (VoIP)
  • Research VoIP
  • Cover equipment needed
  • Cover costs, risks and benefits
  • Who is currently using VoIP?
  • Sign up for and demonstrate vendor products

6
Small office Wi-fi
  • Research product base
  • Research security issues/defenses
  • Be a consultant and propose a system for a house

7
Communication Tasks
  • Transmission system utilization
  • Interfacing
  • Signal generation
  • Synchronization
  • Exchange management
  • Error detection and correction
  • Flow control

8
Communication Tasks
  • Addressing
  • Routing
  • Recovery
  • Message formatting
  • Security and protection
  • Network management

9
Transmission System utilization
  • You want the most bang for the buck
  • Use the same equipment for each department or
    user group
  • Constant battle on this issue for network
    managers between efficiency and effectiveness

10
Utilization throughput vs. response time
  • Throughput
  • the amount of data you can push through in a
    given amount of time
  • Response time
  • the amount of time you have to wait for the
    system to do what you asked it to. Usually
    thought of as How long after I hit the enter key
    do I get a new screen?

11
Interfacing
  • Whatever communication system you choose or use
    must interface with each of the clients or users

12
Signal generation
  • All telecommunications start with electrical
    (electromagnetic) impulses
  • Communication occurs through the transfer of
    electromagnetic impulses
  • These impulses must make it from sender to
    receiver
  • These impulses must be interpretable at the
    receiver

13
Synchronization
  • No sense sending if receiver isnt ready
  • Electromagnetic impulses need to be in the
    correct form at the correct time to be interpreted

14
Exchange management
  • Handled under the topics of
  • Synchronization
  • Flow control

15
Error detection / correction
  • Signals may make it to receiver, and be
    interpretable, but what if they are wrong?
  • Do you care if my 100 deposit gets read by your
    computer as 100,000?
  • Do you care if your order for 20,000 spark plugs
    gets read as 2,000?

16
Flow control
  • Above synchronization is the need to keep the
    receiver from being overwhelmed

17
Addressing / routing
  • Unless you plan to operate in a point-to-point
    environment you need some way of getting these
    electromagnetic impulses to the correct
    destination
  • Different levels of addressing/routing depending
    on whether you are on a LAN, MAN, or WAN

18
Recovery
  • What happens when the telecommunication network
    goes down?
  • Ties in with system utilization
  • The system must either be able to pick up where
    it left off or at least start over from the
    beginning

19
Message formatting
  • The electromagnetic impulses must have the same
    meaning to sender and receiver
  • Signals can be correctly generated, correctly
    synchronized, and without error, but if Im using
    7 bits/byte and you are using 6 bits/byte we
    arent communicating

20
Protection
  • Need to ensure received signal matches the sent
    signal
  • Need to ensure only authorized personnel can use
    the system
  • Would be nice to protect the system against
    viruses

21
System management
  • Someone has to make sure all this happens

22
Network design concern
  • Availability
  • Reliability
  • Maintainability
  • Survivability
  • Performability
  • Testability
  • How easily the above can be verified

23
Network design concern
  • Availability
  • The probability that a piece of equipment (or
    group of equipment) will be available at some
    instance in time (like when you need it)

24
Network design concern
  • Availability
  • Reliability
  • The probability that a piece of equipment (or
    group of equipment) will remain operating for
    some specified period of time, assuming it was
    working at the start

25
Network design concern
  • Availability
  • Reliability
  • Maintainability
  • How easily problems can be diagnosed and repaired

26
Network design concern
  • Availability
  • Reliability
  • Maintainability
  • Survivability
  • The ability of the network to continue performing
    in the face of equipment failures

27
Network design concern
  • Availability
  • Reliability
  • Maintainability
  • Survivability
  • Performability
  • The ability of the network to perform special
    tasks

28
Network design concern
  • Availability
  • Reliability
  • Maintainability
  • Survivability
  • Performability
  • Testability
  • How easily the above can be verified

29
Why do we need networks and architectures?
  • Different software packages
  • Different versions of same packages
  • Different machines
  • Different versions of same vendor machine
  • Different network vendors
  • Different offerings from same vendor

30
Application architectures
  • Application programs do the work for us
  • Easily divided into four parts
  • Storing the data
  • Accessing the data (like SQL)
  • Application logic
  • Presentation logic

31
What are the three architectures?
32
Host-Based
  • Presentation/application/data access logic and
    data storage are all on some super machine
  • Users access the host via inexpensive terminals
    (dumb terminals, or thin clients)
  • Pros/Cons?

33
Client-Based
  • Presentation/application/data access logic are
    all on the client
  • The server just handles the data storage
  • Pros/cons?

34
Client-Server
  • Presentation/application logic are on the client
  • Data access logic and data storage are on the
    server
  • Pros/cons?

35
Figure 2-7
Host Client Client-Server Infrastructure
High Medium
Low Development Low Medium
High Scalability Low Medium High
36
Host based
  • Pros
  • Easy to manage
  • Cons
  • One size doesnt fit all
  • Mainframes require you to all use the same
    applications
  • It took too long to add or modify applications

37
Client based
  • Pros
  • User selected applications
  • More flexibility when choosing applications
  • Cons
  • Very high network loads

38
Some definitions
39
Client
  • A networked information requester
  • Usually a PC or workstation
  • Queries database information from a server

40
Server
  • A computer that holds the information to be
    manipulated by clients
  • Usually a mainframe, minicomputer, or
    high-powered workstation

41
API
  • Application Programming Language
  • Set of functions/programs that allow
    communication between clients/servers

42
Middleware
  • Set of drivers, APIs, and assorted software that
    improves connectivity between clients and servers

43
Middleware
  • Programming interfaces and protocols that fit
    between the applications and the operating
    systems / communications software
  • Allows the different platforms to communicate
  • Much like the network protocols, or the OSI model

44
Middleware
  • Allows different platforms to be accessed
    transparently
  • Same application can access an Oracle, Access,
    Gupta, DB2 database
  • Servers and clients can reside on different types
    of networks
  • Token ring LAN, DECnet ethernet, TCP\IP LAN, etc.

45
Client / Server
  • Clients
  • PCs with user friendly interface
  • Servers
  • Computers
  • Network
  • LAN or WAN
  • Middleware

46
Why the sudden interest?
  • Started at the workgroup/department level
  • Mainframe based applications hindered departments
    from responding quickly to changes in the
    business environment
  • High speed LANs provided the means for clients
    (workgroups) to access servers

47
Why the sudden interest?
  • Workgroups started in the late 1980s, early
    1990s
  • Network speeds have been increasing
  • Desktop computing power has dramatically increased

48
Market Forces Driving Client/Server
  • Downsizing
  • Upsizing
  • Rightsizing
  • Im not sure if Im downsizing, upsizing,
    rightsizing, or capsizing

49
Downsizing
  • The downward migration of business applications
    from mainframes to PCs or workstations
  • Todays workstations are as powerful as last
    decades mainframes

50
Upsizing
  • The bottom-up trend of networking all the
    standalone PCs and workstations at the department
    or work group level
  • Early LANs were implemented to share hardware
    (printers, scanners, etc.)
  • Now LANs are being implemented to share data and
    applications in addition to hardware

51
Rightsizing
  • Moving applications to the most appropriate
    server platform
  • Servers from different vendors can co-exist
  • The network is the system
  • Get the data from the system no longer refers to
    a single mainframe. As a matter of fact, we
    probably dont know where the server physically
    resides!

52
Features
  • Shared resources
  • Customized applications
  • Single point for updates
  • Empowered end-users
  • Open systems
  • Easy to expand systems

53
Challenges
  • No single platform - maintenance headaches
  • Lack of support tools for all the different
    platforms
  • Retraining for all the different platforms will
    probably be required for service staff

54
How does it work?
  • Simply a distributed environment
  • Client sends a request to a server
  • For an application
  • For data
  • Server sends a response
  • Data is transferred

55
Client/server binding
  • Nonpersistent binding
  • Logical connection established between
    client/server
  • Dropped as soon as data is returned to the client
  • Persistent binding
  • Logical connection established between
    client/server
  • Maintained even when data is returned

56
Dont mainframes do the same?
  • Clients are not dumb terminals
  • Application can reside at the client in
    client/server environment
  • Client interface is always the same with
    client/server
  • Improved productivity, and improved ease-of-use

57
How does the WWW work?
  • 2-tier architecture

58
The Internet
  • Just a huge collection of connected host
    computers
  • Your PC is NOT a host computer
  • Elan is the UCCS host computer
  • And your UNIX account resides on Elan

59
Internet host computers vs. PCs
  • Internet hosts
  • Route Internet traffic
  • Hold Web pages
  • Are called servers in this role
  • PCs
  • Access the Internet
  • Are called clients in this role

60
Minimum requirements for the Internet
  • Host computers
  • Clients
  • You and I
  • Software to tell our computers to search
  • Called browsers
  • Some way to access the host computers, or hook up
    to the internet
  • Called ISPs (Internet Service Providers)

61
Question
  • Who provides all those Internet host computers?
  • Are the Internet host computers PCs, mainframes,
    supercomputers, or something else?

62
How does traffic flow over the Internet?
63
Internet infrastructure
  • Major backbone networks
  • Similar to our Interstate highway systems
  • Regional networks
  • Similar to major roads in each city (Powers)
  • Local networks
  • Similar to your neighborhood roads
  • This is where you get on with your ISP

64
Internet traffic flow
  • Messages are broken into packets
  • Packets are directed by routers
  • All machines must understand TCP/IP
  • Protocol, or language spoken on the Internet
  • All machines are identified by an IP address

65
Internet naming conventions
  • http//www.yahoo.com/movies/T2.htm

protocol
internet host computers name
folder on the machine
document you are looking for
66
Question
  • Where is the IP address in that last slide?

67
Connecting to the Internet
  • Youll need access to an Internet Host computer
    (called ISPs)
  • You can use your existing phone line and a modem
  • You can get a higher speed phone line (DSL)
  • You can use your cable TV link (cable modem)

68
How do I find stuff?
  • Search engines
  • Yahoo!, Google, Excite
  • Search by categories
  • Search using keywords
  • Boolean operators help narrow down keyword
    searches

69
How does e-mail work?
  • Sits on top of the internet
  • POP 3 (Post Office Protocol)
  • Protocol that holds your email on a particular
    server until you are ready for it
  • But then puts it on whatever client you are using
  • IMAP4
  • Protocol that holds your email on a particular
    server even after youve read it

70
Email systems
  • POP
  • Email stored on Internet host, downloaded to your
    client when you open email
  • IMAP
  • Similar to POP, but you can keep your email on
    the Internet host
  • Web based
  • Email is stored on the Internet host

71
Email etiquette
  • Terse messages, not lengthy ones
  • Use Bcc when sending to distribution lists
  • Acknowledge emails
  • Be careful with what you write email does not
    convey body language
  • Scan attachments for viruses prior to sending

72
Additional applications
73
Communications architecture
  • A set of modules that help facilitate the
    transfer of information

74
SAPs
  • Each computer on the network needs a unique
    address
  • How is this address assigned?
  • Each application on an individual computer needs
    a unique address
  • This application address is called a SAP

75
What is a PDU?
  • The application layer produces data
  • Each layer of the communication architecture
    wraps the data with header information
  • The end result (the data header) is called a
    PDU
  • There are transport layer PDUs, network layer
    PDUs, etc.

76
OSI Model
Peer to Peer
Application
Messaging
Named Pipes
API
Presentation
Session
NetBIOS
Sockets
TLI
APPC
Transport
TCP IP
SPX IPX
LU 6.2 APPN
NetBEUI
Network
IEEE 802.2
LLC
IEEE 802.5
IEEE 802.3
SDLC
ISDN
MAC
Fiber Optic
Coax
Twisted Pair
Physical
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