Network Fundamentals

Network Topologies

· Ring – IBM - Token Ring

· Star – Mainframe approach

· Bus – Ethernet – 1973 Xerox Parc

Each moves packets of information from machine to machine. The difference is in linkages and control of message movements.

Carrier-sense multiple access with collision detection – CSMA / CD

Transmission Protocols

• Agreed principles for line access, collision avoidance, receipt verification, error identification, etc.

• OSI Layers

– Physical – RS 232

– Data link – data frame creations

– Network – routing messages around network

– Transport – network-independent packet creation

– Session – User connection on Network

– Presentation – translate message to application

– Application – user services like security

Moving from Network to Network - Routers

• Packet switching v circuit switching – breaking messages into packets
• Configuration tables
• Stay local – or leave the LAN? Subnet masks
• Domain name servers and the “dotted quad”
• Moving down the internet – direction and service quality

Basics of the Internet

• ARPANet and the four college network
• Military applications and topological choices
• TCP/IP protocols