Terrestrial microwaves are in the low gigahertz range, which limits all communications to line-of-sight. These Earth-orbiting systems are capable of receiving and relaying voice, data, and TV signals. Cellular and PCS systems use several radio communications technologies. The systems divide the region covered into multiple geographic areas.
Terrestrial microwaves are in the low gigahertz range, which limits all communications to line-of-sight. These Earth-orbiting systems are capable of receiving and relaying voice, data, and TV signals.
Cellular and PCS systems use several radio communications technologies. The systems divide the region covered into multiple geographic areas.
Each area has a low-power transmitter or radio relay antenna device to relay calls from one area to the next area. Wireless LANs use spread spectrum technology to enable communication between multiple devices in a limited area.
Free-space optical communication uses visible or invisible light for communications. In most cases, line-of-sight propagation is used, which limits the physical positioning of communicating devices.
Exotic technologies[ edit ] There have been various attempts at transporting data over exotic media: It was implemented in real life in Node networking Apart from any physical transmission media there may be, networks comprise additional basic system building blocks, such as network interface controllers NICsrepeatershubsbridgesswitchesroutersmodemsand firewalls.
Any particular piece of equipment will frequently contain multiple building blocks and perform multiple functions. Network interfaces[ edit ] An ATM network interface in the form of an accessory card.
A lot of network interfaces are built-in. A network interface controller NIC is computer hardware that provides a computer with the ability to access the transmission media, and has the ability to process low-level network information.
For example, the NIC may have a connector for accepting a cable, or an aerial for wireless transmission and reception, and the associated circuitry. In Ethernet networks, each network interface controller has a unique Media Access Control MAC address—usually stored in the controller's permanent memory.
The size of an Ethernet MAC address is six octets. The three most significant octets are reserved to identify NIC manufacturers.
These manufacturers, using only their assigned prefixes, uniquely assign the three least-significant octets of every Ethernet interface they produce. Repeaters and hubs[ edit ] A repeater is an electronic device that receives a network signalcleans it of unnecessary noise and regenerates it.
The signal is retransmitted at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cable that runs longer than meters.
With fiber optics, repeaters can be tens or even hundreds of kilometers apart.
A repeater with multiple ports is known as an Ethernet hub. Repeaters work on the physical layer of the OSI model.
Repeaters require a small amount of time to regenerate the signal. This can cause a propagation delay that affects network performance and may affect proper function.
As a result, many network architectures limit the number of repeaters that can be used in a row, e. Hubs and repeaters in LANs have been mostly obsoleted by modern switches. Bridges[ edit ] A network bridge connects and filters traffic between two network segments at the data link layer layer 2 of the OSI model to form a single network.
This breaks the network's collision domain but maintains a unified broadcast domain. Network segmentation breaks down a large, congested network into an aggregation of smaller, more efficient networks.
Bridges come in three basic types: Directly connect LANs Remote bridges: Remote bridges, where the connecting link is slower than the end networks, largely have been replaced with routers. Switches[ edit ] A network switch is a device that forwards and filters OSI layer 2 datagrams frames between ports based on the destination MAC address in each frame.
It can be thought of as a multi-port bridge. If an unknown destination is targeted, the switch broadcasts to all ports but the source. Switches normally have numerous ports, facilitating a star topology for devices, and cascading additional switches.
Routers[ edit ] A typical home or small office router showing the ADSL telephone line and Ethernet network cable connections A router is an internetworking device that forwards packets between networks by processing the routing information included in the packet or datagram Internet protocol information from layer 3.
The routing information is often processed in conjunction with the routing table or forwarding table.Cisco ASA DMZ Configuration Example Design Principle. The network diagram below describes common network requirements in a corporate environment.
Network Solutions, Inc. Page 6 of 15 2. The building is a new construction and the interior has not been built out leaving great latitude as to the design of the network. Note: If you are not sure about EIGRP, please read my EIGRP tutorial..
Question 1. Explanation. When a router has no EIGRP feasible successor and the successor route to that destination network is in active status (the successor route is down, for example) a route recomputation occurs. Create network maps of your entire network, both local and remote, in just minutes and easily export a network diagram to a graphic image, Microsoft Visio, as well as an XML scheme.
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This local area network (LAN. A PSTN network topology is the switching network topology of a telephone network connected to the public switched telephone network (PSTN)..
In the United States and Canada, the Bell System network topology was the switching system hierarchy implemented and operated from the late s to the s for the purpose of integrating the diverse array of local telephone companies and telephone.