Networking Concepts

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A network is two or more computer systems that are linked by a transmission medium and share one or more protocols that enable them to exchange data.

• consists of nodes and links
  • nodes are devices that send, receive, and forward data
    • 2 kinds of nodes:
      • intermediary nodes perform a forwarding function
      • end system nodes are those that send and receive data traffic
        • aka hosts
  • links are the communications pathways between them

Client-Server vs. Peer-to-Peer Networks

• End system nodes are classified as either clients or servers:
  • server makes network applications and resources available to other hosts
  • client consumes the services provided by servers

Client-Server Network

In a client-server network:

• some nodes act mostly as clients
• servers are more powerful computers
• application services and resources are centrally provisioned, managed, and secured

Peer-to-Peer Network

• each host acts as both client and server
• decentralized model
  • provision, management, and security is done individually
• small peer-to-peer network is referred to as a workgroup

Appliances, Applications, and Functions

• Networks have appliances, applications, and functions
  • appliance
    • is a computer with an operating system and software designed to perform a particular network role
    • E.g. switches, routers, wireless access points, firewalls, IPS, IDS, load balancers, proxies, etc.
    • can be deployed as physical hardware or as virtual appliance
  • application
    • nodes and links of networking are deployed to run services
    • services are shared applications that allow the network to do useful work
      • e.g., sharing files, email
  • function
    • networks can be configured to perform different functions
    • E.g., the security properties of a VPN allow devices to join a local network from across the internet