Networking - 1.1 - The intermediary devices and their roles

Examples:

• Network Access Devices (Hubs, switches, and wireless access points)
• Internetworking Devices (routers)
• Communication Servers and Modems
• Security Devices (firewalls)

Network Media

Communication across a network is carried on a medium
The signal encoding is different for each media type.

• Metallic wires, the data is encoded into electrical impulses
• Fiber optic cables - pulses of light, within either infrared or visible light ranges.
  Wireless transmission, electromagnetic waves
  Criteria for choosing a network media are:
• The distance the media can successfully carry a signal.
• The environment in which the media is to be installed.
• The amount of data and the minimum required speed.
• The cost of the media and installation

Services and Processes

Processes running on the intermediary network devices perform these functions:

• Regenerate and retransmit data signals
• Maintain information about what pathways exist through the network and internetwork
• Notify other devices of errors and communication failures
• Direct data along alternate pathways when there is a link failure
• Classify and direct messages according to QoS priorities
• Permit or deny the flow of data, based on security settings

Networking Representations

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