Transcript Session4 PowerPoint Slides

Designing Real-World Networks
CSC 363
4 February, 1999
Announcements
• Midterm exam due on Tuesday, 9 Feb at
noon
• Group projects--how are they going? Who’s
doing what?
Some Real World Networks
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Ethernet
Token Ring
FDDI
ATM
ARCnet (we won’t cover this one--not in
use anymore)
Ethernet Characteristics
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Many flavors
CSMA/CD
Mature
Flexible
Ethernet Operation
• Signaling on the wire
• Collision Detection
• Backoff Algorithm
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?
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?
Problem:
• Every once in awhile, your 20-stations 10Base2 network
goes down. You’ve 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 can’t really move his computer, and since 10Base2
requires the cabling to go in and out of the computer, you
can’t 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?
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?
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?
100Mbps Ethernet
• 100VG AnyLAN
• Fast Ethernet
Compare and Contrast
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?
Problem:
• You have a client who wants to migrate to
100Mbps Ethernet but doesn’t have the
budget to replace all the installed category 3
wiring in his building. Which network
architecture do you recommend?
Token Ring
• Interface equipment (MAU, MSAU (IBM),
SMAU
• Cabling
• Patch cables
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.
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
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?
ATM
• Point-to-point switched network
• 53-octet (8 bits *53) cells
• PVCs
• SVCs
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?
LAN Design
• Complexity
• Technology
• Physical Plant
Decision Factors in LAN
Complexity
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Network scale
Distance between computers
What kind of traffic will the network carry
What kind of software will be used
Special Requirements
Budget
Network Designs-simple to
complex
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Peer network
single-server network
Multi-server network
Multi-server high-speed backbone network
Enterprise network
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?
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 email and Marketing’s 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.
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?
Decision Factors in Networking
Technologies
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Appropriate to traffic and software
Appropriate to physical plant
Appropriate to budget
Appropriate to distances and max. nodes
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?
Problem:
• You have been asked to prepare a plan for
the future growth of your organization’s
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?
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?
Decision Factors in Physical
Plant
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Network topology
Cost per location
Distance Limitations
Other Limitations
Bandwidth