Ch.2 – Networking Fundamentals Getting past some basics…

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Ch.2 Networking FundamentalsGetting past some
basics

• CIS 81 and CST 311
• Cabrillo College and CSUMB
• Rick Graziani
• Fall 2005

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Overview

• Remember, we are just beginning to herd the cats.
• Much of this will become clearer LATER!
• The more we learn, the more all of this will come
  into focus!

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What is Networking?

• Networking - the interconnection of workstations,
  peripherals, terminals and other devices.
• Whatis.com In information technology,
  networking is the construction, design, and use
  of network, including the physical (cabling, hub,
  bridge, switch, router, and so forth), the
  selection and use of telecommunication protocol
  and computer software for using and managing the
  network, and the establishment of operation
  policies and procedures related to the network.

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The Evolution of Data networks

• Peer-to-peer Enabling communications between two
  computers, without relying on a computer server
  (client/server).
• LANs (Local Area Networks) Enabling
  communications between groups of computers and
  other devices within an office, company, etc.,
  including servers and printers.
• WANs (Wide Area Networks) Enabling
  communications between individual computers,
  computers on different LANs, etc.

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Network Media Symbols
Becoming obsolete
Usually a LAN connection
The Serial connection symbol usually represents
some sort of WAN connection such as leased line
(T1), ISDN, Frame Relay, ATM, asynchronous
dial-up (modem), etc.
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Symbols for Networking Devices
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Network topologies
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Network topologies

• Network topology defines the structure of the
  network.
• Physical topology Actual layout of the wire or
  media.
• Bus
• Star, Extended Star
• Ring
• Logical topology Defines how the media is
  accessed by the hosts for sending data.
• Broadcast or multi-access
• Token passing

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Bus Topology

• A bus topology uses a single backbone segment
  (length of cable) that all the hosts connect to
  directly.

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Other Bus Topologies
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In the 70s I was usually working on my bus
topology
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Ring Topology

• A ring topology connects one host to the next
  and the last host to the first.
• This creates a physical ring of cable.
• Becoming less common.

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Token Ring

• Ring topologies use a token passing (logical
  topology).
• Token Ring NIC and Hub (or MAU)
• Token Ring networks are becoming obsolete and not
  part of this curriculum.

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Star Topology

• A star topology connects all cables to a central
  point of concentration.
• This point is usually a hub or switch, which will
  be described later in the chapter.

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Extended Star Topology

• An extended star topology uses the star topology
  to be created.
• It links individual stars together by linking the
  hubs/switches.
• This, as you will learn later, will extend the
  length and size of the network.

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Mesh Topology
Circuit and Packet Switched networks could be
full or partial mesh.

• A mesh topology is used when there can be
  absolutely no break in communications, for
  example the control systems of a nuclear power
  plant.
• Each device has its own connections to all other
  hosts.
• This also reflects the design of the Internet,
  which has multiple paths to any one location.
• There are also full mesh and partial mesh
  topologies, both physical and logical, which will
  be discussed in later courses.

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Full Mesh and Switched Telephone Lines
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Network protocols
010010100111000111010011100101001000111101 ...

• Protocol - Set of rules and conventions that
  govern a particular aspect of how devices on a
  network communicate.
• Including format, timing, sequencing, and error
  control in data communication.
• Protocol suites are collections of protocols that
  enable network communication from one host
  through the network to another host.
• Without protocols, the computer cannot make or
  rebuild the stream of incoming bits from another
  computer into the original format.

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Network protocols

• Examples
• Ethernet
• TCP/IP protocol suite
• IP
• TCP
• UDP
• ARP

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Network Technologies

• LANs
• MANs
• WANs

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Local-area networks (LANs)

• Some common LAN technologies are
• Ethernet
• Token Ring
• FDDI

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Wide-area networks (WANs)

• Some common WAN technologies are
• Modems (Asynchronous)
• Integrated Services Digital Network (ISDN)
• Digital Subscriber Line (DSL)
• Frame Relay
• US (T) and Europe (E) T1, E1, T3, E3
• Synchronous Optical Network (SONET)

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Metropolitan-area networks (MANs)

• A MAN is a network that spans a metropolitan area
  such as a city or suburban area.
• A MAN usually consists of two or more LANs in a
  common geographic area.
• For example, a bank with multiple branches may
  utilize a MAN.

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Importance of bandwidth

• Bandwidth - The amount of information that can
  flow through a network connection in a given
  period of time.

• Available at http//www.thinkgeek.com

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Analogies
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Measurement

• In digital systems, the basic unit of bandwidth
  is bits per second (bps).
• Bandwidth is the measure of how much information,
  or bits, can flow from one place to another in a
  given amount of time, or seconds.
• Later The size of a bit!

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Limitations

• Bandwidth varies depending upon
• Type of media
• Type of technology and protocol (LAN, WAN,
  wireless, etc.)
• The physics of the media account for some of the
  difference.

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Throughput

• Throughput - The amount of data transferred from
  one place to another or processed in a specified
  amount of time. (wikopedia.com)
• Often far less than the maximum possible digital
  bandwidth of the medium that is being used.
  Internetworking devices
• The following are some of the factors that
  determine throughput
• Type of data being transferred
• Network topology
• Number of users on the network
• User computer
• Server computer
• Power conditions

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Digital versus Analog

• Digital Signals
• A signal whose state consists of discrete
  elements such as high or low, on or off
• Analog Signals
• A signal which is analogous to sound waves
• telephone lines are designed to carry analog
  signals

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Digital and Analog Bandwidth

• Bandwidth The width or carrying capacity of a
  communications circuit.
• Digital bandwidth the number of bits per second
  (bps) the circuit can carry
• used in digital communications
• measure in bps
• Analog bandwidth the range of frequencies the
  circuit can carry
• used in analog communications such as voice
  (telephones)
• measured in Hertz (Hz), cycles per second
• voice-grade telephone lines have a 3,100 Hz
  bandwidth

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Sound Waves
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ISO and the OSI Model

• The International Organization for
  Standardization (ISO) released the OSI reference
  model in 1984, was the descriptive scheme they
  created.
• ISO. A network of national standards institutes
  from 140 countries working in partnership with
  international organizations, governments,
  industry, business and consumer representatives.
  A bridge between public and private sectors.
  www.iso.ch

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ISO and the OSI Model

• According to ISO, "ISO" is not an abbreviation.
  It is a word, derived from the Greek isos,
  meaning "equal", which is the root for the prefix
  "iso-" that occurs in a host of terms, such as
  "isometric" (of equal measure or dimensions) and
  "isonomy" (equality of laws, or of people before
  the law).
• The name ISO is used around the world to denote
  the organization, thus avoiding the assortment of
  abbreviations that would result from the
  translation of "International Organization for
  Standardization" into the different national
  languages of members.
• Whatever the country, the short form of the
  organization's name is always ISO.
  www.whatis.com

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OSI Model

• It breaks network communication into smaller,
  more manageable parts.
• It standardizes network components to allow
  multiple vendor development and support.
• It allows different types of network hardware and
  software to communicate with each other.
• It prevents changes in one layer from affecting
  other layers.
• It divides network communication into smaller
  parts to make learning it easier to understand.

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OSI Model

• OSI (Open Systems Interface) was released as a
  suite of protocols to be used as the Internet
  standard.
• However, TCP/IP became the de facto standard.
• The OSI reference model is the primary model for
  network communications.
• Although there are other models in existence,
  most network vendors, today, relate their
  products to the OSI reference model, especially
  when they want to educate users on the use of
  their products.

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OSI Model
The use of this model can be confusing and will
become clearer later!

• The OSI reference model allows you to
• view the network functions that occur at each
  layer
• a framework that you can use to understand how
  information travels throughout a network.
• understand, visualize, and troubleshoot the
  sending and receiving data on a network
• visualize how information, or data packets,
  travels from application programs, through a
  network medium (e.g. wires, etc.), to another
  application program that is located in another
  computer on a network, even if the sender and
  receiver have different types of network media
• Note The Application Layer of the OSI model
  refers to networking applications, and not user
  applications.

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OSI layers
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OSI layers
Usually not referred to.
Usually not referred to.
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OSI Layer 1 Physical Layer

• The physical layer defines the electrical,
  mechanical, procedural, and functional
  specifications for activating, maintaining, and
  deactivating the physical link between end
  systems.
• Signals, network media (cables, wireless, ),
  layer 1 devices
• Layer 1 devices include
• Repeaters
• Hubs

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OSI Layer 1 Physical Layer

• Determines how are the bits to be transferred
  over the physical medium.

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Repeaters

• Signals can only travel so far through media
  before they weaken, and become garbled.
• This weakening of signals is called attenuation.
• Attenuation increases when
• Media distances are lengthened
• Nodes are added to the media

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The Repeater

• Repeaters are Layer 1 internetwork devices used
  to combat attenuation.
• Repeaters take in weakened signals, clean them
  up, regenerate them, and send them on their way
  along the network.

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Repeaters Extend Distances
100 M
NODE A
NODE B

• By using repeaters, the distance over which a
  network can operate is extended.
• Example 10Base-T (a wiring standard) is allowed
  to run 100 meters. One repeater can double this
  distance to 200 meters!

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Repeater Layer 1 Device
Signal come in signal go out. (after I amplify
it)

• Repeaters are Layer 1 devices.
• They do NOT look at Layer 2, Data Link (MAC,
  Ethernet) addresses or Layer 3, IP Addresses.

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Hub

• Hub is nothing but a multiport repeater.
• Hubs are Layer 1 devices.
• Data that comes in one port is sent out all other
  ports, except for the port it came in on.
• Hubs are sometimes called
• Ethernet concentrators
• Multiport repeaters
• In Token Ring nets, Multi-station Access Units
  (MAU or MSAU)

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Hub Layer 1 Device

• Hubs are Layer 1 devices.
• They do NOT look at Layer 2, Data Link (MAC,
  Ethernet) addresses or Layer 3, IP Addresses.

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Repeaters

• In the old days, repeaters were typically used
  to extend the size or length of a bus-topology
  network.
• Repeaters take a signal in on one end and
  regenerate that signal out the other end.
• In most networks (LANs), repeaters have been
  replaced by hubs, which have been mostly replaced
  by switches.
• MORE LATER!

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Hubs

• Hubs allow computers and other network devices to
  communicate with each other, and use a star
  topology.
• Like a repeater, a hub regenerates the signal.
• Hubs have the same disadvantage as a repeater,
  anything it receives on one port, it FLOODS out
  all other ports.
• Wherever possible, hubs should be replace by
  switches.
• More LATER!

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OSI Layer 2 Data Link Layer

• The data link layer provides reliable transit of
  data across a physical link. In so doing, the
  data link layer is concerned with physical (as
  opposed to logical) addressing, network topology,
  network access, error notification, ordered
  delivery of frames, and flow control.
• Frames and Layer 2 protocols
• Layer 2 devices include
• Switches
• Bridges

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Switches

• Switches are the core devices in todays modern
  LANs.
• Switches are Layer 2 devices, like bridges.
• Switches keep tables of MAC addresses.
• Switches keep track of and examine Layer 2, Data
  Link addresses (MAC addresses) more later.
• Switches learn about devices on each port and
  decide whether or not it needs to forward the
  traffic Flood or Filter.

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Switches
Etherfast 5-port 10/100 switch with one free
nic47.99  Click here for lease options! (Data
Warehouse)

• Switches filter or flood. more later
• Switches can have a number of different layer 2
  features and may cost anywhere from 50 to over
  100,000
• What is a layer 3 switch? Later, but it is
  nothing more than a switch with a router.

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Switches

• Switches will be discussed
• More this semester
• More in CIS 83.
• More in course Multilayered Switched Networks
• LAN design, media types, VLANs, VLAN Trunking
  Protocol, ISL, 802.1Q, Spanning Tree (802.1d),
  Inter-VLAN routing, Multilayer Switching, Flow
  Masks, HSRP, VACLs, Multicasting, and IGMP.

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Switches
Switch

• Switches look a lot like hubs, but internally are
  much different.
• Switches can learn where devices are on the
  network, so they do not have flood information
  (frames), but can FILTER them so the information
  only goes out the port towards the destination
  device.
• Switches also uses a star topology.

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Bridges

• A bridge is a two port switch.
• In the early days there were other types of
  bridges such as translation bridges that joined
  two different types of networks such as Ethernet
  and Token Ring.

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Network Interface Card (NIC)
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Network Interface Card (NIC)

• Network Interface Card (NIC)
• www.whatis.com A network interface card (NIC) is
  a computer circuit board or card that is
  installed in a computer so that it can be
  connected to a network. Personal computers and
  workstations on a local area network (LAN)
  typically contain a network interface card
  specifically designed for the LAN transmission
  technology, such as Ethernet or token ring.
  Network interface cards provide a dedicated,
  full-time connection to a network. Most home and
  portable computers connect to the Internet
  through as-needed dial-up connection. The modem
  provides the connection interface to the Internet
  service provider.
• Data Link, Layer 2 Device

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Network Interface Card (NIC)
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Network Interface Card (NIC)

• Network Interface Card (NIC)
• Layer 2, Data Link Layer, device
• Connects the device (computer) to the LAN
• Responsible for the local Layer 2 address (later)
• Common Layer 2 NICs
• Ethernet
• Token Ring
• Common Bandwidth
• 10 Mbps, 10/100 Mbps, 10/100/1000 Mbps

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Network Interface Card (NIC)

• Routers with Ethernet and Token Ring Interfaces
  also have NICs.

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OSI Layer 3 Network Layer

• The network layer provides connectivity and path
  selection between two host systems that may be
  located on geographically separated networks.
• IP Addressing, routing and Layer 3 protocols
• Layer 3 devices include
• Routers

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The Router

• The purpose of a router is to examine incoming
  packets, choose the best path for them through
  the network, and then switch them to the proper
  outgoing port.
• Routers work at Layer 3, the Network Layer.
• Routers examine Layer 3 addresses IP (legacy
  technologies IPX, Appletalk, etc.)

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Router

• Routers can also connect different Layer 2
  technologies, such as Ethernet, Token-ring, and
  different serial technologies such as ISDN, PPP,
  etc.
• However, because of their ability to route
  packets based on Layer 3 information, routers
  have become the backbone of the Internet, running
  the IP protocol.

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Router
IMP (Interface Message Processor)
Juniper Router

• A router connects different networks or subnets.
• A router connects
• LAN to LANs
• LANs to WANs
• WANs to WANs

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Router

• Much more on routing
• CIS 82 Routing theory, routing protocols, router
  configuration
• CIS 83 EIGRP, Single Area OSPF, classful and
  classless routing protocols
• CIS 185 Advanced Routing, multi-area OSPF,
  EIGRP, IS-IS, BGP, VLSM, CIDR, route
  redistribution, summarization and optimization.

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Router

• A router is used to separate or segment one
  network from another network.
• This will make more sense LATER!

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Devices and their layers
Transceiver

• Hosts and servers operate at Layers 2-7 they
  perform the encapsulation process.
• Routers Layers 1 through 3, make decisions at
  layer 3
• Switches and NICs Layers 1 and 2, make decisions
  at layer 2
• Hubs and transceivers Layer 1, no decisions to
  make

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Ethernet and TCP/IP

• Ethernet TCP/IP are the most pervasive LAN
  protocols, and are often used together.

TCP/IP
Ethernet
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(No Transcript)
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Peer-to-peer communications

• In order for data to travel from the source to
  the destination, each layer of the OSI model at
  the source must communicate with its peer layer
  at the destination.
• This form of communication is referred to as
  peer-to-peer.
• During this process, the protocols of each layer
  exchange information, called protocol data units
  (PDUs).
• Each layer of communication on the source
  computer communicates with a layer-specific PDU,
  and with its peer layer on the destination
  computer as illustrated in Figure

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TCP/IP model

• TCP/IP was developed as an open standard.
• This meant that anyone was free to use TCP/IP.
• This helped speed up the development of TCP/IP as
  a standard.
• Although some of the layers in the TCP/IP model
  have the same name as layers in the OSI model,
  the layers of the two models do not correspond
  exactly.

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TCP/IP model

• Some of the common protocols specified by the
  TCP/IP reference model layers. Some of the most
  commonly used application layer protocols include
  the following
• File Transfer Protocol (FTP)
• Hypertext Transfer Protocol (HTTP)
• Simple Mail Transfer Protocol (SMTP)
• Domain Name System (DNS)
• Trivial File Transfer Protocol (TFTP)
• The common transport layer
• protocols include
• Transport Control Protocol (TCP)
• User Datagram Protocol (UDP)
• The primary protocol of the
• Internet layer is
• Internet Protocol (IP)

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OSI and TCP/IP
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Detailed encapsulation process

• All communications on a network originate at a
  source, and are sent to a destination.
• The information sent on a network is referred to
  as data or data packets.
• If one computer (host A) wants to send data to
  another computer (host B), the data must first be
  packaged through a process called encapsulation.

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Detailed encapsulation process

• Networks must perform the following five
  conversion steps in order to encapsulate data
• Build the data.
• Package the data for end-to-end transport.
• Add the network IP address to the header.
• Add the data link layer header and trailer.
• Convert to bits for transmission.

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Data Encapsulation Example
Application Header data
Application Layer
Layer 4 Transport Layer
Layer 3 Network Layer
Layer 2 Network Layer
010010100100100100111010010001101000
Layer 1 Physical Layer
Let us focus on the Layer 2, Data Link, Ethernet
Frame for now.
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This will make much more sense later!
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Ch.2 Networking FundamentalsGetting past some
basics

• CIS 81 and CST 311
• Cabrillo College and CSUMB
• Rick Graziani
• Fall 2005