Networking

1
Networking

• WEEK 1-Wednesday
• By
• Norrima Mokhtar

2
Networking and Telecommunications.

• The big picture of networking and
  telecommunications can be broken up according to
  its protocols into the following four areas
• Local Loops
• LANs
• MANs
• WANs

3
Local Loops

• In telephony, the local loop (also referred to as
  a subscriber line) is the physical link or
  circuit, that connects from the point of the
  customer premises to the edge of the carrier, or
  telecommunications service provider, network.

4
(No Transcript)
5
Local Loops

• The Local Loop is often called "the last mile",
  and it refers to the last mile of analog phone
  line that goes from the telephone company's
  central office (CO) to your house. Typical local
  loop protocols are
• Voice lines
• Modem connections
• ISDN (Integrated Services Digital Network)
• ADSL (Asymmetrical Digital Subscriber Line)
• Cable Modems

6
Local Loops

• Cable modems are not part of the local loop but
  do fall into the category of the last mile, or
  how high speed digital communication gets to the
  premises (home).
• It would incredibly expensive to replace the
  existing cabling structure and because this
  cabling was designed for voice communications
  rather than digital, all of these protocols are
  needed to overcome the existing cabling
  limitations in the local loop and provide high
  speed digital data transmission.

7
Local Area Networks (LANS)
8
Local Area Networks (LANS)

• LANs (local area networks) are networks that
  connect computers and resources together in a
  building or buildings that are close together.
• The components used by LANs can be divided into
  cabling standards, hardware, and protocols.

9
Local Area Networks (LANS)

• Examples of cabling standards used on LANs are
• Ethernet cabling standards IEEE 802.3 (10Base5),
  IEEE 802.3a (10Base2),IEEE 802.3i (10BaseT)
• Unshielded Twisted Pair (UTP)
• Shielded Twisted Pair (STP)

10
Ethernet

• Ethernet is a family of frame-based computer
  networking technologies for local area networks
  (LANs).
• The name comes from the physical concept of the
  ether.
• It defines a number of wiring and signaling
  standards for the physical layer, through means
  of network access at the Media Access Control
  (MAC)/Data Link Layer, and a common addressing
  format.
• Ethernet is standardized as IEEE 802.3.
• The combination of the twisted pair versions of
  Ethernet for connecting end systems to the
  network, along with the fiber optic versions for
  site backbones, is the most widespread wired LAN
  technology.
• It has been in use from the 1990s to the present,
  largely replacing competing LAN standards such as
  token ring, FDDI, and ARCNET.
• In recent years, Wi-Fi, the wireless LAN
  standardized by IEEE 802.11, is prevalent in home
  and small office networks and augmenting Ethernet
  in larger installations.

11
Twisted Pair Cabling

• Twisted pair cabling is a form of wiring in which
  two conductors are wound together for the
  purposes of canceling out electromagnetic
  interference (EMI) from external sources,
  electromagnetic radiation from the UTP cable, and
  crosstalk between neighboring pairs.
• Twisting wires decreases interference because the
  loop area between the wires (which determines the
  magnetic coupling into the signal) is reduced.
• In balanced pair operation, the two wires
  typically carry equal and opposite signals
  (differential mode) which are combined by
  addition at the destination.
• The common-mode noise from the two wires (mostly)
  cancel each other in this addition because the
  two wires have similar amounts of EMI that are
  180 degrees out of phase.
• This results in the same effect as subtraction.
  Differential mode also reduces electromagnetic
  radiation from the cable, along with the
  attenuation that it causes.

12
Shielded Twisted Pair (STP)

• Shielded twisted pair is a special kind of copper
  telephone wiring used in some business
  installations. An outer covering or shield is
  added to the ordinary twisted pair telephone
  wires the shield functions as a ground.

13
Unshielded Twisted Pair (UTP)

• The more common kind of wire that is installed to
  your home is unshielded twisted pair.

14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
UTP
18
LANS Connectors

• RJ45
• RJ11
• Hermaphroditic connectors
• RS-232
• BNC

19
LANs connectors
20
(No Transcript)
21
RJ11

• RJ11 is a physical interface often used for
  terminating telephone wires. It is probably the
  most familiar of the registered jacks, being used
  for single line POTS(Plain old telephone service)
  telephone jacks in most homes and offices in
  North America and many other countries.

22
RJ11
23

• The RJ45 network connector and the RJ11 look
  superficially alike, but the RJ11 has only four
  leads (or contacts) whereas the RJ45 has eight.
• In computer systems, the RJ11 is used primarily
  for connecting to modems.
• There are many different adapters for RJ11
  connectors, because telephone ports vary widely
  from country to country.

24
RJ11
25
Hermaphroditic Connector for fiber optic cables
26
RS232

• In telecommunications, RS-232 (Recommended
  Standard 232) is a standard for serial binary
  data signals connecting between a DTE (Data
  terminal equipment) and a DCE (Data
  Circuit-terminating Equipment).
• It is commonly used in computer serial ports. A
  similar ITU-T standard is V.24.

27
RS232

• Serial, full-duplex communication port with
  maximal 115200kb/s transfer rate.
• Used to connect external modems, mice and various
  specialized electronic devices like PLCs or
  meters.

28
(No Transcript)
29
(No Transcript)
30
LANs protocols
31
(No Transcript)
32
(No Transcript)
33
(No Transcript)
34
(No Transcript)
35
(No Transcript)
36
(No Transcript)
37
(No Transcript)
38
(No Transcript)
39
(No Transcript)
40
MANs

• Metropolitan Area Networks (MANs) are networks
  that connect LANs together within a city.

41
MANs

• A Metropolitan Area Network is a system of LANs
  connected throughout a city or metropolitan area.
  
• MANs have the requirement of using
  telecommunication media such as voice channels or
  data channels.
• Branch offices are connected to head offices
  through MANs.
• Examples of organizations that use MANs are
  universities and colleges, grocery chains, and
  banks.

42
MANs

• It may be a single network such as a cable
  television network, or it may be a means of
  connecting a number of LANs into a larger network
  so that resources may be shared LAN-to-LAN as
  well as device-to-device.
• A MAN may be wholly owned and operated by a
  private company, or it may be a service provided
  by a public company, such as a local telephone
  company.
• Many telephone companies provide a popular MAN
  service called Switched Multi-megabit Data
  Services (SMDS).

43
Examples of MAN protocols are

• RS232, V35
• X.25 (56kbps), PADs
• Frame Relay (up to 45 Mbps), FRADs
• Asynchronous Transfer Mode (ATM)
• ISDN (Integrated Services Digital Network) PRI
  and BRI
• Dedicated T1 lines (1.544 Mbps) and Fractional
  T1
• T3 (45 Mbps) and OC3 lines (155 Mbps)
• ADSL (Asymmetrical Digital Subscriber Line) up
  to 8 Mbps
• XDSL (many different types of Digital Subscriber
  Lines)

44
Metropolitan-Area Network Services
                                              
                                  
45
(No Transcript)
46
WANs

• Wide Area Networks (WANs) connect LANs together
  between cities.
• The main difference between a MAN and a WAN is
  that the WAN uses Long Distance Carriers.
  Otherwise the same protocols and equipment are
  used as a MAN.

47
(No Transcript)
48
WANs

• In contrast to LANs (which depend on their own
  hardware for transmission), WANs may utilize
  public, leased, or private communication devices,
  usually in combinations, and can therefore span
  an unlimited number of miles.
• A WAN that is wholly owned and used by a single
  company is often referred to as an enterprise
  network.

49
Criteria for Classification of Computer Network

• The following are the characteristics used to
  classify different types of computer networks
• Topology
• Topology is nothing but the geometric management
  of positioning computer systems to involve them
  in the form of a network. For example, Star
  topology, Bus topology, etc.
• Protocol
• The protocols are nothing but the set of rules
  and signals that are used for communication in
  the network. For example, 'Ethernet' is one of
  the most popular protocols for LANs.
• Architecture
• Networks can usually be classified in the
  following two types -
• Peer-to-peer architecture.
• Client-Server architecture.

50
NETWORK TOPOLOGIES

• The term topology refers to the way a network is
  laid out, either physically or logically.
• Two or more devices connect to a link two or
  more links form a topology.
• The topology of a network is the geometric
  representation of the relationship of all the
  links and linking devices (usually called nodes)
  to each other.
• There are five basic topologies possible mesh,
  star, tree, bus, and ring.

51
Multipoint Line Configuration
52
Categories of Topologies
53
NETWORK TOPOLOGIES

• These five labels describe how the devices in a
  network are interconnected rather than their
  physical arrangement.
• For example, having a star topology does not mean
  that all of the computers in the network must be
  placed physically around a hub in a star shape.
• A consideration when choosing a topology is the
  relative status of the devices be linked. Two
  relationships are possible peer-to-peer, where
  the devices share the link equally, and
  primary-secondary, where one device controls
  traffic and the others must transmit through it.
• Ring and mesh topologies are more convenient for
  peer-to-peer transmission, while star and tree
  are more convenient for primary-secondary, bus
  topology is equally convenient for either.

54
Mesh

• In a mesh topology, every device has a dedicated
  point-to-point link to every other device.
• The term dedicated means that the link carries
  traffic only between the two devices it connects.
  
• A fully connected mesh network therefore has n(n
  - l)/2 physical channels to link n devices.
• To accommodate that many links, every device on
  the network must have 7 input/output (I/O) ports.

55
(No Transcript)
56
Star

• In a star topology, each device has a dedicated
  point-to-point link only to a central controller,
  usually called a hub.
• The devices are not directly linked to each
  other.
• Unlike a mesh topology, a star topology does not
  allow direct traffic between devices.
• The controller acts as an exchange. If one device
  wants to send data to another, it sends the data
  to the controller, which then relays the data to
  the other connected device.

57
(No Transcript)
58
Tree

• A tree topology is a variation of a star. As in a
  star, nodes in a tree are linked to a central hub
  that controls the traffic to the network.
• However, not every device plugs directly into the
  central hub.
• The majority of devices connect to a secondary
  hub that in turn is connected to the central hub.
• The central hub in the tree is an active hub. An
  active hub contains a repeater, which is a
  hardware device that regenerates the received bit
  patterns before sending them out.
• Repeating strengthens trans- missions and
  increases the distance a signal can travel.

59
(No Transcript)
60
Bus

• The preceding examples all describe
  point-to-point configurations. A bus topology, on
  the other hand, is multipoint. One long cable
  acts as a backbone to link all the devices in the
  network.
• Nodes are connected to the bus cable by drop
  lines and taps. A drop line is a connection
  running between the device and the main cable. A
  tap is a connector that either splices into the
  main cable or punctures the sheathing of a cable
  to create a contact with the metallic core.
• As a signal travels along the backbone, some of
  its energy is transformed into heat. Therefore,
  it becomes weaker and weaker the farther it has
  to travel.
• For this reason there is a limit on the number of
  taps a bus can support and on the distance
  between those taps.

61
(No Transcript)
62
Ring

• In a ring topology, each device has a dedicated
  point-to-point line configuration only with the
  two devices on either side of it.
• A signal is passed along the ring in one
  direction, from device to device, until it
  reaches its destination. Each device in the ring
  incorporates a repeater.
• When a device receives a signal intended for
  another device, its repeater regenerates the bits
  and passes them along.

63
(No Transcript)
64
Tutorial

• Give four main protocols in Networking.
• What is Local Loop?
• What is LANs?
• What is MANs?
• What is WANs?
• Gives and explain types of network topology?