Designing Real-World Networks

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Designing Real-World Networks

• CSC 363
• 4 February, 1999

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Announcements

• Midterm exam due on Tuesday, 9 Feb at noon
• Group projects--how are they going? Whos doing
  what?

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Some Real World Networks

• Ethernet
• Token Ring
• FDDI
• ATM
• ARCnet (we wont cover this one--not in use
  anymore)

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Ethernet Characteristics

• Many flavors
• CSMA/CD
• Mature
• Flexible

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Ethernet Operation

• Signaling on the wire
• Collision Detection
• Backoff Algorithm

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Problem

• You need to connect, with Ethernet, two buildings
  in the same college campus. The buildings are 980
  miles apart, as the crow files. Which medium will
  you use?

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Problem

• You have four Ethernet stations to attach for a
  small accounting firm on a tight budget. All
  stations are located in the same room. Which
  medium will you use?

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Problem

• Every once in awhile, your 20-stations 10Base2
  network goes down. Youve traced the problem to a
  secretary who occasionally rolls his chair over
  his thinnet cable, breaking the network
  connection momentarily, which causes your NetWare
  file server to drop connections to all the
  clients. You cant really move his computer, and
  since 10Base2 requires the cabling to go in and
  out of the computer, you cant do anything about
  the location of the thinnet cable, either. All
  the network adapters in your LAN are
  10Base2/10BaseT combo adapters. What can you do
  to make certain no single faulty cable can bring
  down your network?

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Problem

• You have a large (400-station) Ethernet network
  to design. Your client wants to use the most
  flexible architecture possible, because they
  intend to upgrade to either faster versions of
  Ethernet or possible ATM in the next five years.
  Which medium will you use? Will you use any other
  types of media in portions of the network?

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Problem

• You need to connect two networks together across
  a busy street. The city will not grant a
  right-of-way to dig or tunnel under the street,
  and municipal ordinances prevent the use of an
  aerial cable. Which medium will you use?

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100Mbps Ethernet

• 100VG AnyLAN
• Fast Ethernet

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Compare and Contrast
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Problem

• You have a client who is installing a new UTP
  network with 50 new, Pentium class PCs. Her
  graphics design company will be using the
  computers to manipulate complex graphical
  advertising materials. Which network architecture
  do you recommend?

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Problem

• You have a client who wants to migrate to 100Mbps
  Ethernet but doesnt have the budget to replace
  all the installed category 3 wiring in his
  building. Which network architecture do you
  recommend?

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Token Ring

• Interface equipment (MAU, MSAU (IBM), SMAU
• Cabling
• Patch cables

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Problem

• Your computer is connected to a 20-node Token
  Ring network. It has not heard from its nearest
  upstream neighbor in seven seconds, the time
  allotted for token passing. Identify and describe
  the process that is activated by your computer.

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FDDI

• Deterministic token passing network
• Multiple frames on the ring at one
  time--full-circle not required before new
  transmissions take place.
• Tokens released when transmit complete

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Problem

• You have set up a FDDI network to include a
  backup server, which performs routing, regularly
  scheduled backups of nodes on the ring. What is
  the FDDI option that enables the backup machine
  to transmit and receive backup data from each
  machine at a regular time, regardless of the
  machine holding the token?

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ATM

• Point-to-point switched network
• 53-octet (8 bits 53) cells
• PVCs
• SVCs

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Problem

• You are designing an experimental ATM backbone
  that will run in parallel with your FDDI backbone
  for one year. You will place traffic on the ATM
  backbone during test cycles and slowly transition
  from the FDDI to ATM backbones in months 10, 110,
  and 12 of the experiment. Should you buy a switch
  with SVC capabilities, PVC capabilities, or both?
  Why?

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LAN Design

• Complexity
• Technology
• Physical Plant

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Decision Factors in LAN Complexity

• Network scale
• Distance between computers
• What kind of traffic will the network carry
• What kind of software will be used
• Special Requirements
• Budget

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Network Designs-simple to complex

• Peer network
• single-server network
• Multi-server network
• Multi-server high-speed backbone network
• Enterprise network

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Problem

• You are in charge of putting together a network
  for a small company. There are only seven
  employees, and each employee needs a computer to
  share e-mail and files with other people in the
  company. Security is not a vital concern, but
  cost is, and all individuals can be depended upon
  to maintain their own computers. Will you install
  a peer network or a single-server network? Why?

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Problem

• Your company has 4 departments-marketing,
  engineering, production, and administration, with
  35, 55, 25, and 10 computers in each division,
  respectively. You have a sever running Windows NT
  that provides file storage for everyone it also
  hosts a SQL database back end for Administration
  and maintains the Internet connection for e-mail
  and Marketings WWW pages. The network is slow
  and getting slower. You have adequate funds for
  modest improvements.
• 1. Explain the advantages of providing each
  department with its own departmental file server.
• 2. Do you need a high-speed backbone between the
  servers? Explain.

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Problem

• You are a networking consultant to a large
  manufacturing corporation that is replacing its
  mainframe computing system with a network of
  specialized servers and PCs. The headquarters
  occupies several large businesses on a campus,
  and there will be over 700 client computers
  connected to the network when installation is
  complete. Huge amounts of information will be
  transferred from department to department (and
  from building to building) as products move
  through the stages of research, development,
  production, and support. How will you tie the
  servers together?

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Decision Factors in Networking Technologies

• Appropriate to traffic and software
• Appropriate to physical plant
• Appropriate to budget
• Appropriate to distances and max. nodes

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Problem

• You have been given the assignment to install a
  network for a small law firm. The computers will
  mostly be used for e-mail, scheduling, word
  processing, and searching for information on
  legal reference CD ROMs. The senior partner in
  the firm has heard about fiber and high-speed
  networking and asks you if a FDDI ring would be
  appropriate for the firm. What is your reply?

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Problem

• You have been asked to prepare a plan for the
  future growth of your organizations network. The
  CIO wants you to consider new technologies that
  will support the bandwidth-intensive applications
  of the future. What technologies will be the
  focus of your report?

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Problem

• You have an installed network of several hundred
  stations and several servers on a 10baseT
  Ethernet network. You would like to increase the
  bandwidth between the servers and the most
  demanding clients but leave the rest of the
  network on 10baseT Ethernet. How will you achieve
  this goal?

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Decision Factors in Physical Plant

• Network topology
• Cost per location
• Distance Limitations
• Other Limitations
• Bandwidth