Categorizing Networks

1
Categorizing Networks
2
(No Transcript)
3
Categories

• Physical scope
• Method of administration
• Network operating system
• Network protocols
• Topology
• Architecture
• OSI

4
Categorizing Networks by Physical Scope

• Local-area network
• Metropolitan-area network
• Wide-area network

5
Local-area Networks (LAN)

• Limited to a specific geographic area
• 2 computers connected together in a home office
• 500 computers computers connected together in an
  office building

6
Local-area Networks

• Network architecture and cable type can limit the
  number of computers a LAN can contain.
• Large LANs can be divided into workgroups.

7
Metropolitan-area Network (MAN)

• Two or more LANs networked together within a city
  or community.
• Less frequently used term.

8
Wide-area Network (WAN)

• A network spanning a large geographical area.
• The internet.
• Private networks.
• Internet vs. internet.

9
Wide-area Network (WAN)

• Intranet a private network within an enterprise
  using the same protocols as the Internet.
• Extranet an intranet but made accessible to
  customers, employees, vendors and partners.

10
Wide-area Networks (WAN)

• Use of public transports such as telephone lines
  slow transmission speed
• Modem 50 kbps
• T1, cable modem, DSL 1 6 mbps
• Slowest Ethernet LAN 10 mbps

11
Wide-area Network (WAN)

• Routed networks.
• For a message to pass from one segment (LAN) to
  another, the packets must pass through a gateway.
• Gateway a specially configured computer or
  router which sends packets to another LAN.

12
Categorizing Networks by Method of Administration

• Peer-to-peer
• Each computer functions as server and client
• Each computer is administered by its user
• Client/server
• Administration is centralized
• Special network operating system (NOS) is required

13
Method of Administration

• A server is a computer that makes its resources
  available for access by other computers on the
  network.
• Data, software, printers
• A client is a computer that accesses the
  resources of the server computer.
• Clients take Servers give.

14
Method of Administration

• Peer-to-peer
• Each computer functions as server and client
• Each computer is administered by its user
• Share Level Security
• Client/server
• Administration is centralized
• Special network operating system (NOS) is
  required
• User Level Security

15
Method of Administration
The operating systems that we think of as client
or desktop operating systems Windows 95/98, NT
Workstation, and Windows 2000 Pro. can and do
function as servers when you create shares on
them to enable other computers to use their
resources.
16
Method of Administration

• If you had a folder named WestProject that you
  wanted to share over the network, you must assign
  a name to the share.
• WP, Wproj, etc.

17
Method of Administration

• The share named WestProject appears in the browse
  list for the server named Gordian.

18
Method of Administration

• Some network operating systems allow for shared
  resources to be published to the master
  directory.
• Active directory in windows 2000.
• NDS tree in Novell Netware.
• This enables users to locate the shared resources
  without knowing which server hosts the resource.

19
Method of Administration

• Dedicated servers
• File servers
• Print servers
• Application servers
• Logon servers
• Web servers
• Mail servers
• News servers
• Remote access servers
• Terminal servers

• Telephony servers
• Cluster servers
• Proxy servers
• Fax servers
• BOOTP servers
• DHCP servers
• Name resolution servers

20
Method of Administration

• A daemon, in UNIX terminology, is a program that
  runs continuously and handles periodic requests
  for services.

21
Method of Administration

• The term client, again refers to a device
  requesting services from a server such as
• Computer, printer, network device, software
  program
• An e-mail program that runs on your desktop
  computer that sends requests to download new
  messages is often called an e-mail client.

22
Method of Administration

• A workstation generally refers to mean any
  desktop computer running any client operating
  system Windows, Linux, Macintosh, etc.
• A workstation can also refer to a powerful
  computer used to run resource intensive
  application software.

23
Method of Administration

• The term host also can refer to computers on a
  network.
• With TCP/IP based networks, host can include any
  network device that is assigned an IP address.

24
Method of Administration

• A node is a connection point on a network.
• A computer
• A printer
• Network device

25
Characteristics of Peer-to-peer Networks

• 10 computers maximum.
• Inexpensive.
• Windows, Linux, Macintosh.
• Decentralized administration.
• User accounts must be created and maintained on
  each node.

26
Share Level Security

• Used by windows for workgroups 3.11 and windows
  95/98
• A password assigned for each shared resource
• To access resource, a user must provide the
  password for that resource
• Users must remember multiple passwords

27
User Lever Security

• Used by windows NT and windows 2000
• A password is assigned to each user
• Access to a specific resource only if user has
  been assigned permissions
• Users need only remember one password

28
Server-based Networks

• Centralized control
• NOS installed on 1 machine
• Netware, Windows NT, Windows 2000 server
• User accounts maintained on server
• Increased performance throughput
• Additional services provided

29
Server-based Administration

• Simplified
• Shared resources stored on server for easy
  location and backup
• Requires a professional network administrator

30
Server-based Security

• Inherently more secure that peer-2-peer
• Requires user accounts and password
• Access to resources are granted through user
  authentication and permissions
• Network administrator assigns permissions to
  individual users and groups of users

31
Categorizing Networks by NOS

• Windows (NT and 2000)
• Netware
• UNIX
• Networks containing more than one server type are
  called hybrid networks

32
Windows Server-based Networks

• Domains
• Primary domain controller
• Security accounts manager (SAM)
• Downlevel domains
• Active directory
• Copies stored on each domain controller

33
Windows Server-based Networks

• What clients can access Windows NT and 2000
  server resources?
• Windows 2000 pro, Windows 95, Windows 98, Windows
  for Workgroups 3.11, MS-DOS
• Macintosh and Linux clients can access resources

34
Netware Server-based Networks

• Bindery database
• NDS organize objects
• Trees
• Replicas
• Context
• Login security
• File and print services

35
(No Transcript)
36
Netware Server-based Networks

• What clients can access NetWare server resources?
• Windows 2000 pro, Windows 95, Windows 98, Windows
  for Workgroups 3.11, MS-DOS
• Client32 software provides full functionality
• Macintosh and Linux clients can access resources
  with appropriate client software

37
UNIX Server-based Networks

• Powerful NOS developed by Bell Labs in 1969
• Linux development and other open standard
  software are recently becoming popular
• Text based and GUI based Administration tools are
  available
• Access granted by user ID and password
• Groups are collections of users with similar
  access permissions which simplify administration

38
UNIX Server-based Networks

• What clients can access UNIX server resources?
• Dumb terminals, Linux, Windows 2000 pro, Windows
  95, Windows 98, Windows for Workgroups 3.11,
  MS-DOS
• Macintosh clients can access resources with
  appropriate client and server software

39
UNIX Server-based Networks

• HP-UX
• SUN solaris
• AIX
• SCO
• etc

40
Hybrid Networks

• Most medium to large networks are hybrids
• All NOS provide interoperability tools
• Client Services for NetWare
• Gateway Services for NetWare
• Microsoft NetWare client
• File and print services
• Macintosh services
• Systems Network Architecture (SNA)
• SAMBA

41
Categorizing Networks by Protocol

• NetBEUI
• IPX/SPX
• TCP/IP
• Others

42
NetBEUI

• NetBIOS Extended User Interface
• Network Basic Input/Output System
• Provides application programming interface
• Developed by IBM
• Unroutable
• Simple to setup no complicated configuration
• Low resource overhead
• Fast

43
IPX/SPX

• Internet Package Exchange/Sequenced Packet
  Exchange
• Novell proprietary protocol
• Minimal configuration
• Faster performance than TCP/IP
• NWLink, IPX/SPX, MacIPX

44
TCP/IP

• Most popular despite being the most difficult to
  configure and being slow
• Flexible addressing scheme extremely routable
• Almost all OS can use it
• Lots of utility tools available
• The protocol of the Internet

45
Others - AppleTalk

• A set of protocols developed by Apple for
  networking Macintosh machines
• LocalTalk
• Slow (230.4 kbps) supports only 32 devices
• EtherTalk
• Used to connect to Ethernet networks
• TokenTalk
• Used to connect to Token Ring networks
• AppleTalk networks use AppleTalk Address
  Resolution Protocol (AARP) to map AppleTalk
  addresses to Ethernet and Token Ring physical
  Media Access Control (MAC) addresses

46
Others - OSI

• Open Systems Interconnection
• Intended to replace TCP/IP
• Developed by the International Organization for
  Standardization (ISO) isos
• Improved set of protocols for less confusion and
  easier standardization of networking products

47
Categorizing Networks by Topology
48
Categorizing Networks by Topology

• Linear Bus
• Ring
• Star
• Mesh
• Hybrid

49
Linear Bus Networks
50
Linear Bus Networks

• Computers in a bus network are connected in a
  line from one to the next
• A bus network requires termination at each end to
  prevent signal bounce
• Usually use thick or thin coax cable and the
  Ethernet 10base2 or 10base5 architure

51
Communications on a BUS Network

• When a computer sends a message, it proceeds to
  each computer on the network
• The NIC examines the headers to determine whether
  the message is addressed to that computer
• If it is not, the message is discarded

52
Advantages of Bus Networks

• Simple and easy to set up
• Relatively inexpensive (less cable)
• Suitable for small, temporary networks (gaming)

53
Disadvantages of Bus Networks

• Passive topology
• Attenuation
• May require repeaters
• A break in the cable

54
Ring Networks
55
Ring Networks

• A bus network where the last computer in the
  chain is connected back to the first computer
• Each computer is connected to two others
• Signal travels in a circle
• A physical ring network uses coax cable
• A logical ring network uses STP cable and
  complies with IEEE 802.5 specifications

56
Communications on a Ring Network

• Communications happen in one direction
• Each computer receives the signal from its
  upstream neighbor and sends it to its downstream
  neighbor.
• Active topology because each computer regenerates
  the signal before passing it on
• Token Ring architecture is generally a logical
  ring. Using a special hub a multistation access
  unit (MSAU)

57
Advantages of a Ring Network

• Easy to troubleshoot
• Simple to set up
• Requires less cable that a star network

58
Disadvantages of a Ring Network

• If the ring is broken, all network communications
  halt
• Adding computers to the ring can be problematic
• The ring must be broken to add the new workstation

59
Star Networks
60
Star Networks

• The most popular LAN topology
• Each computer is connecter to a central hub
• Hubs can be active passive or intelligent
• Passive a connection point, no electricity
• Active boosts the signal before passing along
• Intelligent contains processing chip with
  diagnostic tools
• UTP cabling and Ethernet 10BaseT or 100BaseT
  architecture

61
Communications on a Star Network

• Signal from the sending computers NIC to the hub,
  boosted, and sent back on all ports
• All computers receive the message
• All computers except the one whos NIC address
  matches the message header discard the message

62
Advantages of a Star Network

• Very fault tolerant
• Very flexible
• Easy to add workstations
• Easy to reconfigure the topology
• Easy to troubleshoot

63
Disadvantages of a Star Network

• Cost
• Lots more cable is required
• Hub

64
Mesh Networks

• Every computer on the network has a direct
  connection to every other computer
• Advantages
• The most fault tolerant
• An alternate path exists between two computers
• Disadvantages
• Very, very expensive cable, NICs

65
Hybrid Networks
66
Hybrid Networks

• A network where elements of the previous network
  types are used
• Several hubs can be connected in a bus topology
• Each hub however uses a star topology to connect
  several computers to the network

67
(No Transcript)
68
Categorizing Networks by Architecture

• Includes a set of specifications that take into
  account its
• Physical and logical topologies
• The type a cable used
• Distance limitations
• Media access methods
• Packet size and headers
• Other factors

69
Categorizing Networks by Architecture

• Ethernet
• Token Ring
• AppleTalk
• ARCnet

70
Ethernet Architecture

• Xerox, Digital, Intel (1960s)
• IEEE 802.3 specifications
• Bus or star
• Media access CSMA/CD carrier sense multiple
  access collision detection
• 10 Mbps, 100 Mbps (Fast Ethernet), 1 Gbps

71
Subcategories of Ethernet Networks

• 10Base5
• 10Base2
• 10BaseT
• 100BaseT
• 1000BaseT
• 100BaseVG-AnyLAN
• 10BaseFL
• 100BaseFL

72
10Base2 Ethernet Networks

• Uses thinner (approx. ¼-inch in diameter), less
  expensive, and more flexible cable. Maximum
  segment length is 185 meters.
• These thinnet networks are physically structured
  as a linear bus.
• Easier to set up and work with than thicknet.
  Twist-and-push connectors (called BNC connector)
  are used to connect the cable to a T-connector on
  the network card.
• The transceiver is built into the network card.
• The coaxial cable for a 10Base2 network is 50-ohm
  RG-58A/U or RG-58C/U

73
10BaseT Ethernet Networks

• This is a very popular specification for LANs of
  all sizes.
• It can run on Cat 3 cable, which is already
  installed in many buildings for telephone
  communications.
• New 10BaseT networks are usually set up using Cat
  5 or Cat 5e cable so that it is easy to upgrade
  to 100 Mbps later

74
100BaseT Ethernet Networks

• Refers to Ethernet networks running at 100 Mbps
  over Cat 5 or Cat 5e cable.
• Many NICs and hubs are made to support both 10-
  and 100-Mbps transmission speeds which make it
  easy to upgrade incrementally.
• With proper hardware networks can be segmented so
  one part runs at 10-Mbps while the other part
  runs at 100-Mbps.

75
1000BaseT Ethernet Networks

• Gigabit Ethernet Networks
• This standard was established by IEEE in 1996,
  802.3z.
• The IEEE 802.3ab standard sets specifications for
  the operation, testing, and usage requirements
  for Gigabit Ethernet for distances of up to 100
  m, using four pairs of Cat 5 copper cabling.
• This includes most of the cabling already
  installed in buildings for 10BaseT and 100BaseT
  networks.
• The cost of necessary NICs and hubs are several
  times higher than that of 100-Mbps components.

76
100BaseVG-AnyLAN Ethernet Networks

• This Hewlett Packard developed technology is
  fast, reliable networking architecture that uses
  a special type of hub that functions as an
  intelligent central controller.
• The hub receives the incoming data packet and
  directs it only to the port with the matching
  destination address providing inherent network
  data security.
• These networks are placed into the Ethernet
  category, but they use a different media access
  method, called demand priority, that is defined
  in IEEE specification 802.12.

77
10BaseFL and 100BaseFL Networks

• FL in this specification stands for fiber link
  and these network use baseband signaling over
  fiber optic cable.
• Fiber-optic cabling uses pulse of light instead
  of electrical signals to represent the 0s and 1s
  of binary communication used by computers.
• A big advantage is its resistance to interference
  and attenuation.
• A cable segment under FL specifications can be
  2000 meters in length, which is 4 times that of
  10Base5, over 10 times that of 10Base2, and 20
  times the limit for 10BaseT.

78
Token Ring Networks

• This architecture was developed by IBM in the
  1980s.
• Here, a signal called a token is passed around
  the circle and a computer cannot broadcast until
  the token gets around to it. This means that,
  unlike Ethernet networks, Token Ring networks do
  not experience data collisions. A data collision
  occurs when two computers send at the same time.
• Although logically a ring, Token Ring networks
  are physically laid out as star topologies.
  Defined by IEEE 802.5
• IBM cable types primarily STP. Token Ring cards
  and other components are generally more expensive
  but are highly reliable.
• Older Token Ring components supported only 4-Mbps
  transmissions, but newer implementations can
  transfer data at 16 Mbps.

79
AppleTalk Networks

• Protocol suite to network Macintosh computers.
• AppleShare is a suite of application layer
  protocols that provide file and print sharing.
  AppleShare components which are built into the OS
  include
• AppleShare file server Enables users to access
  the computers resources
• AppleShare print server Provides for sharing of
  printers
• AppleShare PC is a service that runs on DOS
  computers to enable them to access files on an
  AppleShare file server or print to a shared
  AppleShare print server.
• AppleTalk networks can be divided into groups
  called zones, and serve a purpose similar to
  dividing a large network into workgroups.

80
ARCnet Networks

• Attached Resource Computer Network
• Old architecture that uses a token-passing access
  method, but implements the network topology as a
  bus or star instead of as a ring.
• The token is passed in numerical order according
  to the node address, which is an 8-digit binary
  number set on the ARCnet NIC using DIP switches
  or jumpers.
• ARCnet can use coax, UTP, or even fiber-optic
  cable, but it is most commonly associated with
  RG-62/U 90-ohm coax cable.
• ARCnet networks are slow compared to most LAN
  technologies 2.5 Mbps for standard ARCnet,
  although a newer standard called ARCnet Plus
  improves on this considerably, with a top speed
  of 20 Mpbs.

81
Open Systems Interconnect

• OSI
• 1947
• 140 country members
• International Organization for Standardization
  (ISO)
• Greek isos meaning equal
• DoD -gt August 1990
• Protocol suite intended to replace TCP/IP
• http//www.iso.ch/iso/en/ISOOnline.frontpage

82
OSI

• Application - user Programs
• Presentation - data interpretation
• Session - control of sessions between hosts
• Transport - transmission control
• Network - flow control, routing
• Data Link - maintain and release data
• Physical - physical media definition

83
Layer 7 - The Application Layer

• Programs which use services of the network reside
  in this layer. These programs are the ultimate
  consumer of network services of the lower layers.
  The transmission of messages used by these
  programs is the entire goal of the lower
  protocols.

84
Layer 7 - The Application Layer

• Examples of Application Layer programs are
• Telnet.
• File Transfer Protocol FTP.
• SMTP
• Network Filing System NFS (Sun).
• SNMP (Simple Network Management Protocol)
• AppleShare (Apple).
• Netx (Novell).
• DOOM! (iD Software) -).

85
Layer 6 - The Presentation Layer

• This layer is involved in formatting data for the
  purpose of display or printing. Data encryption,
  protocol, data compression and character set
  translation such as ASCII lt--gt EBCDIC are also
  performed by protocols at this layer.

86
Layer 6 - The Presentation Layer

• Examples of Presentation Layer protocols
• HTTP
• Telnet
• AppleTalk Filing Protocol AFP
• E-mail gateway
• Gateway Services for Netware
• Systems Network Architecture gateway

87
Layer 5 - The Session Layer

• This layer establishes connections or
  'conversations' between processes over the
  network.
• Examples of Session Layer protocols
• TCP
• Named Pipes
• NetBIOS
• Apple protocols ASP, ADSP, ZIP, PAP

88
Layer 4 - The Transport Layer

• This layer provides methods of flow control,
  ordering of received data, and acknowledgement of
  correctly received data.
• Ports and Sockets

89
Layer 4 - The Transport Layer

• Some examples of Transport Layer protocols are
• TCP
• User Datagram Protocol UDP
• Netbios/NetBEUI
• Sequenced Packet Exchange SPX (Novell)
• VINES Interprocess Communication Protocol VIPC
• DNS Name Resolution

90
Layer 3 - The Network Layer

• This layer provides to the upper layers a means
  of transmitting "datagrams" over the network to a
  specified host. This datagram service provides no
  confirmation of safe delivery of the information.
  The transmissions are "connectionless" meaning
  that there is no "continuing conversation" set up
  between the two hosts. One datagram may have
  nothing to do with the next one, and indeed, may
  arrive out of order if they are related.
• This layer is also responsible for assigning
  addresses to the hosts and routing packets
  between interconnected networks.

91
Layer 3 - The Network Layer

• Examples of network layer protocols are
• IP - the Internet Protocol
• IPX - a Novell Protocol
• DDP - Datagram Delivery Protocol - an Apple
  Protocol
• Devices
• Routers
• Layer 3 switches

92
Layer 2 - The Data-Link Layer

• This layer is also known as the Media Access
  Layer (MAC) since its function is to provide
  access to the physical media to the upper layers.
  It also is responsible for the detection of
  physical errors, and notification of such errors,
  and establishing and terminating logical links.

93
Layer 2 - The Data-Link Layer

• Two sub layers
• Media Access Control (MAC)
• physical addressing issues
• Logical Link Control (LLC)
• Logical topology

94
Layer 2 - The Data-Link Layer

• Examples of implementations are
• IEEE 802.2 (LLC)
• IEEE 802.3
• IEEE 802.5 (token ring)
• PPP LCP (point to point protocol for serial
  links)
• Devices
• Bridges
• Layer 2 switches

95
Layer 1 - The Physical Layer

• This layer defines the physical media upon which
  the host is communicating through the network.
  The physical medium can be coaxial cable, FDDI
  (fiber), RS232, or even RF.
• This layer defines the specifics of implementing
  a particular transmission medium. It defines the
  type of cable, frequency, terminations, etc. One
  may see the advantage of dividing network
  functionality into layers. The Physical layer
  could be changed to some new technology as it is
  developed without affecting the operation of
  upper layers, provided the inter-layer interfaces
  are implemented properly.

96
Layer 1 - The Physical Layer

• Analog versus digital signaling
• Baseband versus broadband technology
• Asynchronous versus synchronous transmission
• Multiplexing
• Does not add header information to packet
• NIC
• Network architecture
• Media type
• Bus architecture

97
Layer 1 - The Physical Layer

• Some examples of Physical Layer implementations
• Ethernet
• 10Base2
• 10BaseT
• 100baseT
• Token Ring
• Arcnet
• FDDI
• wireless (e.g. FM)

98
Web Sites For More Info

• http//www.netc.org/network_guide
• http//cs.nmhu.edu/osimodel
• http//www.freesoft.org/CIE/Topics
• http//www.gocertify.com/quizzes/osi
• http//lovecraft.die.udec.cl/OS/UNIX/unix-hints-an
  d-hacks/19270033.htm
• http//www.pe.net/rlewis/Resources/james.html
• http//www.randywanker.com/OSI
• http//www.itp-journals.com/OSI_7_layer_model_page
  1.htm

99
(No Transcript)
100
(No Transcript)