NET 101

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NET 101

• CISCO Semester 1
• Chapter 2 Networking Fundamentals
• Karl Wick - SUNY Ulster

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Network Terminology
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Network Terminology

• Network An interconnected system of objects
• Bandwidth The amount of data that can be sent
  along a path in a given amount of time
• LAN Local Area Network
• MAN Municipal Area Network
• WAN Wide Area network

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Digital Bandwidth

• How much information can flow from one place to
  another in a given time
• Bits per second
• kilo, mega or giga bits per second
• More Bandwidth Better Performance

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Bandwidth

• Is limited by hardware and physics
• Has a cost. (Sometimes Substantial)
• Is critical to good performance
• Demand is growing
• Pipe Analogy

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Throughput

• Throughput lt Bandwidth
• Highway Analogy

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Typical LAN Throughput

• Category 5 Twisted Pair Cable
• 10Mbps
• 100Mbps
• 1000Mbps
• Optical Fiber 1000Mbps
• Coaxial Cable 10Mbps

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Typical WAN Throughput

• ISDN 128kbps
• DSL Variable 128kbps to 6.1Mbps
• Frame Relay Variable 128k to 44.7Mbps
• T1 1.544 Mbps E1 2.048 Mbps
• T3 44.7 Mbps E3 34.4Mbps
• OC3 155.25 Mbps
• OC48 2.488 Gbps

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Throughput

• Try to answer the following question, using the
  formula Throughput FileSize /Bandwidth.
• Be sure to convert units of measurement as
  necessary.
• Would it take less time to send the contents of a
  floppy disk full of data (1.44 MB) over an ISDN
  line, or to send the contents of a ten GB hard
  drive full of data over an OC-48 line?

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Solution to Exercise

• 1440 kbytes / 128k bytes per second 11.25
  seconds for the file.
• 10,000,000 kbytes / 2,488,000 kbytes per second
  4.02 seconds

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Models
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The Seven Layer OSI Model

• 7 Application
• 6 Presentation
• 5 Session
• 4 Transport
• 3 Network
• 2 Data Link
• 1 Physical

• Reduces Complexity
• Standardizes Interfaces
• Facilitates Modularity
• Ensures Interoperability
• Accelerates Evolution
• Simplifies Learning

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The Seven Layer OSI Model

• 7 Application
• 6 Presentation
• 5 Session
• 4 Transport Data Transport Rules
• 3 Network Logical Addresses
• 2 Data Link Fixed Addresses
• 1 Physical Wires and Hardware

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Network Devices
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Host Devices

• PC
• MAC
• Printer
• Server

The symbols are NOT standard throughout the
industry. Most are easy to figure out.
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Host Devices

• Devices that connect directly to a network
  segment are referred to as hosts.
• These hosts include computers, both clients and
  servers, printers, scanners, and many other user
  devices.
• These devices provide the users with connection
  to the network.
• The users share, create, and obtain information
  across the network.

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NICs

• NICs adapt the host device to the network medium.
  
• NICs are considered Layer 2 devices
• This address is used to control data
  communication for the host on the network.

Each individual NIC throughout the world carries
a unique code, called a Media Access Control
(MAC) address.
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Media

• The basic functions of media are to carry a flow
  of information, in the form of bits and bytes,
  through a LAN.
• Coaxial cable, optical fiber, and even free space
  can carry network signals, however, the principal
  medium we will study is called Category 5
  unshielded twisted-pair cable (CAT 5 UTP).

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Media

• Patch cables, patch panels, and other
  interconnection components are considered passive
  Layer 1 components because they simply provide
  some sort of conducting path.
• Passive components do not require a power source.

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Repeaters

• The purpose of a repeater is regenerate and
  retime network signals at the bit level to allow
  them to travel a longer distance on the media.

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Repeaters

• Repeaters are single-port "in" and single-port
  "out" devices.
• Repeaters are classified as Layer 1 devices, in
  the OSI model, because they act only on the bit
  level and look at no other information.
• They are active devices because they require
  power to work.

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The 5-4-3 Rule

• This rule states that you can connect five
  network segments end-to-end using four repeaters
  but only three segments can have hosts
  (computers) on them.

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Hubs

• A hub is a repeater with multiple ports.
• Any input signal gets sent to all output ports.
• Allow concentration of signals at a central point

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Bridges

• A bridge is a layer 2 device designed to connect
  two LAN segments.
• The purpose of a bridge is to filter traffic on a
  LAN, to keep local traffic local, yet allow
  connectivity to other parts (segments) of the LAN
  for traffic that has been directed there.

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Bridges

• The bridge keeps track of which MAC addresses are
  on each side of the bridge and makes its
  forwarding decisions based on this MAC address
  list.

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Switches
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Switches

• A Switch is a device like a bridge with many
  ports.
• In fact a switch is called a multi-port bridge,
  just like a hub is called a multi-port repeater.
• They are used to segment networks into smaller
  parts as well as to provide connectivity.
• The difference between the hub and switch is that
  switches make decisions based on MAC addresses
  and hubs don't make decisions at all.

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Switches

• Because of the decisions that switches make, they
  make a LAN much more efficient.
• They do this by "switching" data only out the
  port to which the proper host is connected. In
  contrast, a hub will send the data out all of its
  ports so that all of the hosts have to see and
  process (accept or reject) all of the data on the
  LAN.

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Routers

• Inter-network data flow.
• Best path determination
• Switching to proper port
• Translation
• Regeneration
• Security

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Routers

• Routers make decisions based on groups of network
  addresses (Classes) as opposed to the individual
  MAC addresses like bridges and switches do.
• Routers can also connect different media
  technologies, such as Ethernet, Token-ring, and
  FDDI.
• Routers have become the backbone of the
  Internet, running the IP protocol.
• The purpose of a router is to examine incoming
  packets (layer 3 data), choose the best path for
  them through the network, and then switch them to
  the best outgoing port.

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Clouds

• The purpose of the cloud is to represent a large
  group of details that are not pertinent to a
  situation, or description, at a given time.

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Network Topology

• The structure of the Network
• Physical and Logical

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Topology

• There are two parts to the topology definition
• The physical topology, which is the actual layout
  of the wire (media), and
• The logical topology, which defines how the
  media is accessed by the hosts.

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Physical Topologies
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Logical Topology

• The logical topology of a network is how the
  hosts communicate across the medium.
• The two most common types of logical topologies
  are Broadcast and Token-passing.

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Broadcast Topology

• Broadcast topology simply means that each host
  sends its data to all other hosts on the network
  medium.
• There is no order the stations follow to use the
  network, it is first come, first serve.
• Controlled Chaos!
• This is the way that Ethernet works and you will
  learn much more about this later in the semester.

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Token Passing Topology

• Token-passing controls network access by passing
  an electronic token sequentially to each host.
• When a host receives the token, only that host
  can send data on the network.
• If the host has no data to send, it passes the
  token to the next host and the process repeats
  itself.

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Network Protocols

• Rules of the Road

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Protocols

• How the physical network is built
• How computers connect to the network
• How the data is formatted for transmission
• How that data is sent
• How to deal with errors

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The LAN
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The LAN
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The WAN
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WAN Technologies

• Dial-up Modems
• Integrated Services Digital Network (ISDN)
• Digital Subscriber Line (DSL)
• Frame Relay
• US (T) and Europe (E) Carrier Series T1, E1,
  T3, E3
• Synchronous Optical Network (SONET)
• Cable Modem

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The MAN
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The SAN

• A SAN is a dedicated, high-performance network
  used to move data between servers and storage
  resources.
• Because it is a separate, dedicated network, it
  avoids any traffic conflict between clients and
  servers.

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The SAN

• Storage Area Network
• Performance SANs enable concurrent access of
  disk or tape arrays by two or more servers at
  high speeds, enhanced system performance.
• Availability data can be mirrored using a SAN up
  to 10 kilometers (km) or 6.2 miles away.
• Scalability

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VPN
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The VPN

• A VPN is a private network that is constructed
  within a public network infrastructure such as
  the global Internet.
• Using VPN, a telecommuter can access the network
  of the company headquarters through the Internet
  by building a secure tunnel between the
  telecommuters PC and a VPN router in the
  headquarters.

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The VPN

• A VPN is a service that offers secure, reliable
  connectivity over a shared public network
  infrastructure such as the Internet.
• VPNs maintain the same security and management
  policies as a private network.
• They are the most cost-effective method of
  establishing a point-to-point connection between
  remote users and an enterprise customer's
  network.

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Intranet / Extranet
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Layered Models

• OSI Model released in 1981 by the ISO
• (Not to be confused with the IOS)

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The Seven Layer OSI Model

• 7 Application
• 6 Presentation
• 5 Session
• 4 Transport
• 3 Network
• 2 Data Link
• 1 Physical

• Reduces Complexity
• Standardizes Interfaces
• Facilitates Modularity
• Ensures Interoperability
• Accelerates Evolution
• Simplifies Learning

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Layers in an Abstract Model

• What is flowing?
• In What forms does it exist?
• What rules govern the flow?
• Where does the flow occur?

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Peer to Peer Networking and PDUs
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The OSI Model

• See 2.3.4 Drag and Drop Exercise

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OSI model vs TCP/IP Model

• Application
• Presentation
• Session
• Transport
• Network
• Data Link
• Physical

• Application
• Transport
• Internet
• Network Access

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Some TCP/IP Protocols
Application
Transport
Internet
Network Access
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Data Encapsulation
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Layers and Hardware

• Layer 1-7 Workstations
• Layer 3 Router
• IP (Logical Addresses)
• Layer 2 Bridge, Switch
• Hardware (MAC) Addresses
• Layer 1 Media, Repeater, Hub, Transceiver

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Summary

• Bandwidth
• LAN, MAN, WAN, SAN can you eat Green Eggs and
  Ham?
• Models
• Protocol Data Units / Encapsulation
• VPN
• Terminology and Symbology