Basics Matter Bits, Bytes & Code Multiplexing Compression Protocols & LANs

Figure 1.2 Noise amplified on the analog line, eliminated on digital service.

Bits A bit = the smallest unit of information –On or off signals –Analog bits –Digital bits

Bytes 8 bits –A character Code - bytes in a common format Examples of ASCII code – W – ? – Return

Figure 1.1 One cycle of an analog wave, 1 hertz (Hz).

Broadband Multiple simultaneous streams Examples –Wireline –Wireless Why the growth? –Enterprises –Consumers

Compression  A way to make networks more efficient  Abbreviating text –Common characters  Compressing video  Not sending stationary objects  Matching compression algorithms at each end

Where is Compression used? Internet What is its impact?

Figure 1.3 Multiplexing.

Types of Multiplexing Time division æBased on strict timing æEveryone gets an equal turn Statistical division æFirst come, first served æOr prioritization

Protocols A protocol is a set of rules for communicating between computers. Why are they needed?

Protocol Functions Who goes first? Are you ready? I got your message There are errors This is a high priority message Who is sending?

How do Protocols Differ? HTML & XML VoIP Security protocols Layer 3 vs. Layer 4

LANs Characteristics –Ownership –Limited geography –High speeds –Shared devices Devices on LANs Changes in LANs

Figure 1.4 LAN architecture. Architecture: how devices fit together in a network.

Figure 1.5 Rack-mounted and chassis-based switches.

The Work Environment How has the way your organization conducts business changed in the last five years? Which technologies have enabled these changes? What’s next?

Figure 1.6 Home LAN.

Figure 1.7 Edge and core routers.

Recap äA Bit is ____ –Bits sent as analog signals have the following disadvantages: –Bits sent as digital signals the following advantages: äBytes are: äASCII code is: äMultiplexing makes better use of _____ by _____ äCompression adds efficiencies to networks by ____ ä______ changes the format of what is sent ä______ does not change the format of what is transmitted

Recap Continued 7Protocols are important because they: 7Layers simplify changes because they: &What do we mean by a layer 3 device versus a layer 4 device? 7Characteristics of LANs are: 7Switches perform the following functions: 7Routers are needed to: 7Edge devices are more complex than core devices because they: