Transcript CSC 363: Local Area Networks

CSC 363: Local Area Networks
DePaul University
Winter Quarter 1999
LoriLee M. Sadler
Intro to Course
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How to contact me
Office Hours
Course Components
Schedule
Small Group Project
• 4 Cases from which to choose
• Final product
• Group registration on the web
The LAN Lab
• Access hours
• ID required
• What’s up there
Why do we network computers?
Basic Terms
• Clients
• Peers
• Servers
Problem:
• You’re installing a small network for a
collections agency. There will be only five
stations on the network. Cost is an issue,
and the company would prefer not to
dedicate an individual’s time to maintaining
a network. However, the agency is also
concerned about keeping its data safe, and
the users are not sophisticated users.
Network Types
• Server-based
• Peer to Peer
• Hybrid
Server-Based Networks
• Also called client-server networks
• Servers
– responsible for security and administration
• single login required for network resources
– network services (e.g., printing, file storage)
• Clients
– typically less powerful than servers
– need client software to access network services
Domains
• Unique to server-based networks
• =>collections of networks and services that
share security trust information
• Domain controllers handle security and
permissions
• PDC=>
• BDC=>
Server-based Networks
pros & cons
• Advantages
– central security &
admin
– Optimized dedicated
servers
– Single-password
security
– Scales to large # of
users
• Disadvantages
– Dedicated servers are
more expensive than
plain old computers
– Expensive NOS and
clients
– Requires dedicated
sysadmin
Peer Networks
• Also called peer-to-peer networks
• No servers--every machine is a client and a
server
• Users control access and security to each
networked resource
Workgroups
• Typically grouped by users rather than by
services or resources
• Password access to individual networked
resources
• Peer machines not optimized for resource
sharing
Peer Networks
Pros and Cons
• Advantages
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Cheap
Easy to set up
No sysadmin
Users control access &
“Security”
– No reliance on other
computers
• Disadvantages
– All advantages are also
disadvantages
– Inefficient use of peer
equipment
– Intrusive, easy to break
security
– Bad idea for large
networks
Peer Security vs. Server Security
• Peer Security
– One user or all users-no user-level security
– Each shared resource
must have its own
password
– Lots of passwords
means more points for
hacking
• Server Security
– Centrally managed
security
– Security controlled by
groups of users and
appropriate resources
Hybrid Networks
• Combines aspects of peer-to-peer and server
networks
• All the advantages of server-based networks
and most of peer-to-peer
• Some of the disadvantages of server-based
networks
Would a Peer Network be good
for the Collections Agency?
Would a Server-based Network
be good for the Collections
Agency?
Server types
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File Servers
Print Servers
Application Servers
Message Servers
Database Servers
Server Software
• Called Network Operating System (NOS)
– Windows NT
– Novell Netware
• Requires matching clients
Server Hardware
• Typically more powerful than a client
• NT requires a minimum of:
– Pentium processor
– 16MB of RAM
• Reality Check
– Pentium II
– 64-256MB RAM
– Large hard drive
Client Hardware
• 486 or better
• 4MB of RAM or better
Problem: You are considering
networking topologies for a
network for a telemarketing firm.
• When would a ring network be appropriate?
• When would a star network be appropriate?
• When would a bus network be appropriate?
Network Topologies
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Bus
Ring
Star
Mesh
Bus Networks
Ring Networks
Star Networks
Mesh Networks
together with high-performance
long-distance links, and servers
within the building must be
linked together with a high-speed
backbone. Hundreds of clients
computers in each building must
be inked together inexpensively.
What media will you use?
Network Media
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Copper
Glass
Air
Radio
Copper Properties:
Glass Properties:
Air Properties:
Radio Properties:
Network protocols:
• Hardware protocols
• Hardware-software protocols
• Software protocols
Decision Tree for NetworksNetwork Type
Decision Tree for Servers
Decision Tree for Topologies
Decision Tree for Media