Chapter 1: Logical and Physical Network Topologies
Chapter Outline
1. On the Test
1.1. Recognize the following logical or physical network topologies given a schematic diagram or
description: star/hierarchical; bus; mesh; ring; wireless.
4.10. Given a troubleshooting scenario involving a network with a particular physical topology (i.e., bus,
star/hierarchical, mesh, ring, and wireless) an including a network diagram, identify the network area
affected and the cause of the problem.
2. Understanding Computer Networking
a. Networking is the process of connecting two or more devices together in order to share resources.
b. Resources can be hardware or software.
c. Hardware: printers, CD-ROMS, modems
d. Software: files, folders, applications
e. Reduced costs
f. Increase productivity
g. Increases usefulness and efficiency of computers
3. Understanding Network Structure
a. Defined by:
i. Size of area that it covers
ii. Type of security being used
b. Two basic types of networks:
i.
Local Area Network (LAN)
ii. Wide Area Network (WAN)
4. Local Area Network
a. Limited to one or more buildings in close proximity
b. Does not use a public carrier
c. Categorized as:
i. Peer-to-peer
ii. Client-server
5. Peer-to-Peer Network
a. Limited in size, no more than 10 nodes
b. All computers are equal members.
c. No centralized security
d. Uses share-level security.
e. Assigns passwords to shares.
f. Easy and inexpensive to implement
6. Client-Server Network
a. One or more servers centrally control security.
b. Servers run a network operating system (NOS).
c. Administrators assign user names and passwords.
d. Uses user-level security.
e. Access to shared resources is granted to a user or group.
1
f. May be any size
7. Wide Area Network (WAN)
a. Unlimited in size and scope
b. WANs are used to connect LANs.
c. WANs use telecommunications lines and one or more routers.
d. Data transfer speeds on WAN are slower than LAN.
e. Largest WAN today is the Internet.
8. Topologies
a. Logical topology
b. Determines media access methods:
i. Collision Sense Multiple Access with Collision Detection
ii. Token passing
c. Physical topology
d. Location and arrangement of nodes
e. How they are interconnected
f. Includes network hardware
g. Most common: star, bus, ring, and wireless
9. Star Topology
a. Most common topology in use today
b. Each node is connected directly to a MAU.
c. Commonly uses twisted pair cable
d. Advantages of a star topology:
i.
Easy to install
ii.
Failure of a single node or cable segment affects only that node.
iii.
Network faults are easier to troubleshoot and repair.
iv.
Components are common and supported by many manufacturers.
e. Disadvantages of a star topology:
i.
The MAU constitutes a potential single point of failure.
ii.
The star requires more wiring than other topologies.
10. Bus Topology
a. Linear topology using several pieces of cable in linear arrangement
b. Uses coaxial cable to add BNC connectors.
c. Must be terminated on each end.
d. Advantages of the bus topology:
i.
Uses less cable and hardware than other topologies.
ii.
Less expensive
iii.
Easier to manage and keep track of wiring
iv.
Simpler to install.
e. Disadvantages of the bus topology:
i.
A single break can bring down a segment or the entire network.
ii.
Adding additional nodes may affect network performance.
I. Can be tough to troubleshoot connection problems
II. Coaxial cable and network adapter cards are more difficult to find.
2
11. Mesh Topology
a. Every node has a connection to every other node
b. Provides a high level of fault tolerance
c. The Internet uses a hybrid mesh
d. Advantages of the mesh topology:
i.
Provides a high level of fault tolerance
ii.
Network problems are generally easy to isolate
e. Disadvantages of the mesh topology:
i.
Complexity makes installation and management difficult
ii.
Redundancy makes it expensive
iii.
Reconfiguration of the network or the addition of another node affects all of the other
nodes
12. Ring Topology
a. A “circle” of cable connects each device to another
b. Data travels around the circle in one direction
c. Uses token passing
d. Advantages of the ring topology:
i.
Requires less wire than a star network
ii.
Each workstation can act as a repeater to regenerate the signal
e. Disadvantages of the ring topology:
i.
Lack of fault tolerance
ii.
Most rings are actually wired as a star
13. Wireless Topology
a. Use either radio frequency (RF) or infrared (IR)
b. Ad hoc mode
c. When devices connect directly to each other
d. Infrastructure or multipoint
e. Nodes connect to an access point that is wired to a network
f. Advantage is mobility
3