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. A repeater is an electronic device that receives a network signal , cleans it of unnecessary noise and regenerates it.
Sustaining a Global Social Network: a quasi‐experimental study
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. 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. 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. 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.
A router uses its routing table to determine where to forward packets. A destination in a routing table can include a "null" interface, also known as the "black hole" interface because data can go into it, however, no further processing is done for said data, i.
Collaborating for Social Impact
Modems MOdulator-DEModulator are used to connect network nodes via wire not originally designed for digital network traffic, or for wireless. To do this one or more carrier signals are modulated by the digital signal to produce an analog signal that can be tailored to give the required properties for transmission. Modems are commonly used for telephone lines, using a digital subscriber line technology. A firewall is a network device for controlling network security and access rules.
Firewalls are typically configured to reject access requests from unrecognized sources while allowing actions from recognized ones. The vital role firewalls play in network security grows in parallel with the constant increase in cyber attacks. A communication protocol is a set of rules for exchanging information over a network. In a protocol stack also see the OSI model , each protocol leverages the services of the protocol layer below it, until the lowest layer controls the hardware which sends information across the media. The use of protocol layering is today ubiquitous across the field of computer networking.
This stack is used between the wireless router and the home user's personal computer when the user is surfing the web. Communication protocols have various characteristics. They may be connection-oriented or connectionless , they may use circuit mode or packet switching , and they may use hierarchical addressing or flat addressing.
The complete IEEE protocol suite provides a diverse set of networking capabilities. The protocols have a flat addressing scheme. They operate mostly at levels 1 and 2 of the OSI model. IEEE It is standardized by IEEE It offers connection-less as well as connection-oriented services over an inherently unreliable network traversed by data-gram transmission at the Internet protocol IP level. At its core, the protocol suite defines the addressing, identification, and routing specifications for Internet Protocol Version 4 IPv4 and for IPv6, the next generation of the protocol with a much enlarged addressing capability.
They were originally designed to transport circuit mode communications from a variety of different sources, primarily to support real-time, uncompressed, circuit-switched voice encoded in PCM Pulse-Code Modulation format. It uses asynchronous time-division multiplexing and encodes data into small, fixed-sized cells. This differs from other protocols such as the Internet Protocol Suite or Ethernet that use variable sized packets or frames.
ATM has similarity with both circuit and packet switched networking.
This makes it a good choice for a network that must handle both traditional high-throughput data traffic, and real-time, low-latency content such as voice and video. ATM uses a connection-oriented model in which a virtual circuit must be established between two endpoints before the actual data exchange begins. While the role of ATM is diminishing in favor of next-generation networks , it still plays a role in the last mile , which is the connection between an Internet service provider and the home user. A network can be characterized by its physical capacity or its organizational purpose.
Use of the network, including user authorization and access rights, differ accordingly. A nanoscale communication network has key components implemented at the nanoscale including message carriers and leverages physical principles that differ from macroscale communication mechanisms. Nanoscale communication extends communication to very small sensors and actuators such as those found in biological systems and also tends to operate in environments that would be too harsh for classical communication. A personal area network PAN is a computer network used for communication among computer and different information technological devices close to one person.
Some examples of devices that are used in a PAN are personal computers, printers, fax machines, telephones, PDAs, scanners, and even video game consoles. A PAN may include wired and wireless devices. The reach of a PAN typically extends to 10 meters. A local area network LAN is a network that connects computers and devices in a limited geographical area such as a home, school, office building, or closely positioned group of buildings. Each computer or device on the network is a node. Wired LANs are most likely based on Ethernet technology. The defining characteristics of a LAN, in contrast to a wide area network WAN , include higher data transfer rates , limited geographic range, and lack of reliance on leased lines to provide connectivity.
A home area network HAN is a residential LAN used for communication between digital devices typically deployed in the home, usually a small number of personal computers and accessories, such as printers and mobile computing devices.
Patti Anklam | Net Work
An important function is the sharing of Internet access, often a broadband service through a cable TV or digital subscriber line DSL provider. A storage area network SAN is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to make storage devices, such as disk arrays, tape libraries, and optical jukeboxes, accessible to servers so that the devices appear like locally attached devices to the operating system.
A SAN typically has its own network of storage devices that are generally not accessible through the local area network by other devices.
- Food is central to cultural vitality!
- RF and Microwave Passive and Active Technologies.
- The Cloud DBA-Oracle : Managing Oracle Database in the Cloud;
- Home Front!
The cost and complexity of SANs dropped in the early s to levels allowing wider adoption across both enterprise and small to medium-sized business environments. The networking equipment switches, routers and transmission media optical fiber, copper plant, Cat5 cabling, etc.
For example, a university campus network is likely to link a variety of campus buildings to connect academic colleges or departments, the library, and student residence halls. A backbone network is part of a computer network infrastructure that provides a path for the exchange of information between different LANs or sub-networks.
A backbone can tie together diverse networks within the same building, across different buildings, or over a wide area. For example, a large company might implement a backbone network to connect departments that are located around the world. The equipment that ties together the departmental networks constitutes the network backbone.