NETWORKS THEORY AND PRACTICAL DISCUSSION JOHN KOVACEVICH INFORMATION SERVICES DEPARTMENT TEXAS A&M GALVESTON CAMPUS

TELECOMMUNICATIONS & CHANNELS Synchronous communications: Receiver gets message instantaneously Asynchronous communications: Receiver gets message after some delay Simplex channel: Transmits data in only one direction Half-duplex channel: Transmits data in either direction, but not simultaneously Full-duplex channel: Permits data transmission in both directions at the same time

BASIC TELECOMMUNICATIONS CHANNEL CHARACTERISTICS

TELECOMMUNICATIONS SOFTWARE Network operating system (NOS): Systems software that controls the computer systems and devices on a network Network management software: Protects software from being copied, modified, or downloaded illegally Locates telecommunications errors and potential network problems

VIRTUAL PRIVATE NETWORK (VPN) Private network that uses a public network (usually the Internet) to connect multiple remote locations Provides network connectivity over a potentially long physical distance Supports secure, encrypted connections between a company’s private network and remote users

HUB AND SPOKE NETWORK

WHY IS COPPER LIMITED TO100 METERS AND FIBER IS KILOMETERS? It must be 100m or less in length to be certified. It is possible a longer cable will work - but it is not guaranteed. Shorter Cat 5 cables may also not work if there is a lot of EMI. Signal attenuation appears to be the limiting factor - too much signal loss and you can't guarantee 100 megabits per second.EMI For long distances (1000m to km) use a laser optimized fiber optic cable (OM2, OM3, OM4) and transmit signals by VCSEL (Vertical-cavity surface-emitting laser). Smaller distances can use LEDs to transmit the signal and don’t require the more expensive Laser Optimized cable.

ROUTING TABLE FOR LAB A ROUTER

VLANS – VIRTUAL LOCAL AREA NETWORKS VLAN is a logical grouping of network users and resources connected to administratively defined ports on a switch. A VLAN is treated like its own subnet or broadcast domain. Flat networks, every broadcast packet transmitted is seen by every device on the network regardless of whether the device needs to receive that data or not.

SPANNING TREE PROTOCOL (STP) Ensures a loop free topology Network design for spare (Redundant) links for automatic paths. Invented by Radia Perlman in the 1985 BPDU Bridge Protocol Data Units Blocking, Listening, Learning, Forwarding, Disabled

SHIP CONTROL SYSTEM

BACHMANN NETWORK REDUNDANCY

Redundancy networking on Ethernet basis, full support of TCP/IP-based parallel communication Networking topology freely selectable: star, line, ring and combinations Easy configuration in development environment, integrated diagnostics (status, quality) Programming interface, libraries and system variables for easy creation of applications Network switchover in the same cycle

GLOBAL POSITIONING SYSTEM APPLICATIONS Global navigation satellite system that uses two dozen satellites roughly 11,000 miles above the earth GPS receivers: Have become as small as a cell phone and are relatively inexpensive Are commonly found in automobiles, boats, planes, laptop computers, and cell phones GPS tracking technology: Has become the standard by which fleet managers monitor the movement of their cars