Network Design Includes

Analyzing network requirements
Selecting a network topology
Selecting equipment
Completing the design

Network Topology

The physical or logical arrangement of computers, cables, and other network resources.
Significantly impacts speed, functionality, and scalability of a network.

Bus Single linear cable segment.
Star Central connection point.
Ring Electrically connects in a loop.

Ethernet Classic Topology.
Called a passive/broadcast methodology.
Only one computer at a time transmits but all computers see all packets.
Only the receiving machine reads the entire message.(In theory.)
Each machine just listens to the wire.
Requires cable termination.

Signal Bounce due to incorrect termination or Cable Breaks.
• Media can no longer propagate the signal
• Effectively, backbone runs to and from each computer.
  

Without correct cable termination, the signal reflects (bounces) back down the cable.
May prevent other computers from accessing the cable.
Exclusive to coaxial cable.

Whenever the backbone cable is broken (wire cut, connector failure, machine unplugged, etc.), all network communications may stop.
Cable problems can be difficult to diagnose.
Unplugging a machine from a bus network may break the bus.

Contention
Adding computers slows the network
Common to Ethernet

Over distance, the signal becomes smaller
Common to all topologies

All computers connect to a hub.
Each device is on its own cable segment.
With the exception of the hub, cable failure affects only a single machine. 
Solves Bus Topologies major vulnerability

Only addressee reads the entire broadcast.
Relative to bus, requires more cable.
Requires another component, a hub.

Computers logically connect directly to the next computer in line, forming a loop.
Signals travel in only one direction.
An active technology where each computer either acts on or regenerates the signal.
Utilizes Token passing

Active technology.
Each device sends or receives.
Provides equitable access for all units.
Deterministic resource sharing method.
Used by Token Ring, FDDI, and ArcNet.

Mesh -- Each network device connects to every other device.<>

Cable failures have no impact. (Fault Tolerant.)<>

Another name for star

Another name for ring topology.
Physically a star, logically a ring.

Evaluate Requirements

Step one : evaluate network requirements.
How many devices?
Which network model?
Peer to peer or server based?
What applications?
Fault tolerance/budget?

Step two , diagram the network.
Where possible, utilize a graphics program. Viso Professional