1. 1 Networks: A group of two or more computer systems linked together. There are many types of computer networks, including: local-area networks (LANs) : The computers are geographically close together (that is in the same building). (# relevant for Ecolog-Net) wide-area networks (WANs) : The computers are farther apart and are connected by telephone lines or radio waves. campus-area networks (CANs): The computers are within a limited geographic area, such as a campus or military base. metropolitan-area networks (MANs): A data network designed for a town or city. home-area networks (HANs): A network contained within a user's home that connects a person's digital devices.

2. 2 Network topology Topology/structure AdvantagesDisadvantages Bus structure-easy to install -simply expandable -short cable lengths -net expansion limits -by cable interrupt the net precipitates -complicated access methods Ring structure-large net expansion-complex error tracing -high wiring expenditure -when disturbances net failure Star structure-simple cross-linking -simple extension -high reliability -high wiring expenditure -net failure in case of failure or overloading of the hubs (# relevant for Ecolog-Net)

3. 3 LAN – local area network Simple network: A simple network consists of at least two computers, which are connected by a direct connection (crossover cable) or with a Hub or Switch.

4. 4 LAN – local area network Hub: A common connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets. Switch: In networks, a device that filters and forwards packets between LAN segments.

5. 5 LAN – local area network Network with Internet entrance and print server Router: A device that forwards data packets along networks. A router is connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP’s network (Internet Service Provider). Routers are located at gateways, the places where two or more networks connect.

6. 6 LAN – local area network Radio network - Wireless LAN - WLAN Instead of cable-based connections; A simple Wireless LAN is a local network with an ACCESS POINT for WLAN adapter (network interface cards with antenna), which is attached to the computer or inserted.

7. 7 LAN – local area network Access point: AP Short for Access Point, a hardware device or a computer's software that acts as a communication hub for users of a wireless device to connect to a wired LAN. APs are important for providing heightened wireless security and for extending the physical range of service a wireless user has access to. Network interface card: Often abbreviated as NIC, an expansion board you insert into a computer so the computer can be connected to a network. Most NICs are designed for a particular type of network, protocol, and media, although some can serve multiple networks.