Meta tags:

Headings (most frequently used words):

network, technologies, bus, star, links, point, distributed, connected, topology, contents, topologies, nodes, classification, centralization, decentralization, see, also, references, external, wired, wireless, exotic, interfaces, repeaters, and, hubs, bridges, switches, routers, modems, firewalls, to, daisy, chain, ring, mesh, hybrid, linear, extended, fully, partially,

Text of the page (most frequently used words):
the (340), network (179), and (102), #topology (100), are (61), nodes (57), star (46), for (46), node (43), networks (41), that (41), from (39), can (39), connected (38), data (37), edit (36), physical (36), transmission (34), bus (34), two (34), point (32), between (31), all (30), with (29), ring (26), used (26), this (24), central (24), one (23), computer (22), communication (22), topologies (21), ethernet (20), may (19), link (19), links (19), cable (19), mesh (19), wireless (17), media (17), devices (17), which (17), radio (16), repeaters (16), single (15), peripheral (15), layer (15), optical (14), more (14), have (14), each (14), signal (14), tree (13), hybrid (13), logical (13), other (13), hub (13), use (12), retrieved (12), has (12), technologies (12), but (12), not (12), main (12), medium (12), area (12), twisted (12), using (11), line (11), fiber (11), device (11), cabling (11), linear (11), daisy (11), address (11), switches (11), pair (11), internet (10), types (10), information (10), fully (10), common (10), article (10), electrical (9), archived (9), repeater (9), wired (9), technology (9), also (9), number (9), failure (9), chain (9), way (9), distributed (9), over (9), bridges (9), table (8), telecommunication (8), switched (8), telephone (8), communications (8), original (8), power (8), model (8), when (8), only (8), any (8), access (8), endpoints (8), than (8), based (8), hubs (8), wikipedia (7), telecommunications (7), signals (7), switch (7), control (7), connections (7), there (7), multiple (7), some (7), destination (7), graph (7), uses (7), local (7), ports (7), lans (7), page (6), was (6), different (6), digital (6), structure (6), level (6), large (6), systems (6), often (6), their (6), connecting (6), transmit (6), traffic (6), required (6), hierarchical (6), its (6), however (6), does (6), basic (6), since (6), theory (6), associated (6), end (6), both (6), interface (6), been (6), routing (6), into (6), routers (6), wires (6), cables (6), copper (6), toggle (5), commons (5), september (5), category (5), lan (5), division (5), time (5), circuit (5), switching (5), waves (5), free (5), charles (5), history (5), loop (5), create (5), isbn (5), networking (5), machine (5), pdf (5), serial (5), computers (5), see (5), pairs (5), very (5), high (5), where (5), partially (5), next (5), these (5), will (5), intended (5), connection (5), such (5), example (5), via (5), through (5), referred (5), extended (5), firewalls (5), modems (5), mac (5), osi (5), form (5), most (5), ieee (5), nic (5), low (5), protocols (5), bits (5), per (5), second (5), random (5), contents (4), search (4), mobile (4), view (4), additional (4), categories (4), decentralization (4), protocol (4), space (4), packet (4), bandwidth (4), optic (4), law (4), social (4), system (4), application (4), 2016 (4), what (4), design (4), ribbon (4), interfaces (4), complete (4), degree (4), relay (4), paths (4), connect (4), makes (4), until (4), able (4), packets (4), leaf (4), etc (4), including (4), consists (4), known (4), without (4), every (4), called (4), while (4), distance (4), wire (4), cost (4), message (4), transmitters (4), receivers (4), lines (4), include (4), within (4), controller (4), transmitter (4), various (4), light (4), 802 (4), rates (4), defined (4), speed (4), hide (4), move (4), sidebar (4), about (3), privacy (3), non (3), wikimedia (3), inc (3), last (3), wikidata (3), articles (3), wayback (3), short (3), television (3), cellular (3), frequency (3), list (3), coaxial (3), telegraph (3), cases (3), satellite (3), phone (3), video (3), broadcasting (3), world (3), wide (3), web (3), core (3), related (3), spectrum (3), advanced (3), study (3), 2018 (3), advantages (3), disadvantages (3), bridge (3), interplanetary (3), 2014 (3), type (3), electronics (3), security (3), command (3), configuration (3), designed (3), usually (3), expensive (3), redundant (3), directions (3), them (3), fails (3), disadvantage (3), implement (3), series (3), comes (3), layout (3), port (3), then (3), conventional (3), individual (3), thus (3), isolated (3), path (3), receive (3), must (3), delay (3), prevent (3), trip (3), received (3), others (3), receiving (3), many (3), possible (3), standard (3), interconnected (3), another (3), certain (3), make (3), physically (3), simplest (3), need (3), value (3), communicating (3), performance (3), around (3), passes (3), reaches (3), further (3), flow (3), forms (3), down (3), source (3), breaks (3), particular (3), permanent (3), longer (3), channel (3), classification (3), typically (3), forwards (3), router (3), small (3), multi (3), frames (3), remote (3), three (3), usb (3), possibly (3), distances (3), 232 (3), octets (3), exotic (3), enable (3), several (3), satellites (3), microwave (3), earth (3), terrestrial (3), fibers (3), helps (3), widely (3), million (3), circuits (3), modeled (3), changes (3), arrangement (3), transport (3), tools (3), subsection (3), languages (2), code (2), safety (2), contact (2), policy (2), terms (2), 2026 (2), unsourced (2), statements (2), cs1 (2), maint (2), deprecated (2), archival (2), service (2), description (2), portal (2), global (2), locations (2), wan (2), forward (2), pioneers (2), thomas (2), claude (2), alexander (2), robert (2), metcalfe (2), hooke (2), gray (2), lee (2), john (2), revolution (2), undersea (2), streaming (2), telegraphy (2), platform (2), hypercube (2), grid (2), butterfly (2), arrangements (2), backbone (2), external (2), architecture (2), 2009 (2), analysis (2), rfc (2), 2001 (2), oclc (2), 978 (2), science (2), guide (2), basics (2), 2002 (2), 2012 (2), 2008 (2), april (2), define (2), 2000 (2), third (2), 2011 (2), linux (2), user (2), group (2), demand (2), pin (2), scsi (2), pcl (2), 10152 (2), canopen (2), connector (2), ways (2), 485 (2), part (2), db25 (2), algorithms (2), edition (2), sybex (2), topological (2), cite (2), atis (2), 2007 (2), references (2), distribution (2), scale (2), present (2), diagram (2), parallel (2), broadcast (2), direct (2), set (2), provide (2), mostly (2), displaystyle (2), frac (2), full (2), similar (2), least (2), case (2), special (2), kind (2), first (2), forming (2), they (2), amount (2), keep (2), examining (2), identifier (2), memory (2), lookup (2), transmissions (2), learn (2), still (2), section (2), act (2), originating (2), reception (2), active (2), echo (2), round (2), communicate (2), transmitting (2), result (2), cause (2), centralization (2), those (2), custom (2), architectures (2), interconnect (2), meshed (2), unit (2), distinct (2), always (2), exactly (2), affect (2), grows (2), proportional (2), subscribers (2), aggregate (2), server (2), load (2), increases (2), travels (2), sends (2), intermediate (2), retransmit (2), clients (2), before (2), upon (2), fashion (2), chained (2), top (2), along (2), tier (2), together (2), replaced (2), spoke (2), maximum (2), just (2), limitations (2), easiest (2), advantage (2), adding (2), necessarily (2), same (2), because (2), interference (2), normally (2), higher (2), being (2), simultaneously (2), processed (2), cut (2), improve (2), fault (2), tolerance (2), sent (2), computing (2), ones (2), dynamically (2), dropped (2), needed (2), dedicated (2), actions (2), constant (2), produce (2), processing (2), home (2), office (2), showing (2), capable (2), content (2), url (2), filters (2), addresses (2), domain (2), maintains (2), segments (2), work (2), change (2), even (2), propagation (2), meters (2), runs (2), apart (2), significant (2), manufacturers (2), either (2), ability (2), carried (2), permit (2), building (2), controllers (2), limits (2), sight (2), spread (2), collectively (2), voice (2), personal (2), price (2), options (2), business (2), consist (2), ranges (2), unshielded (2), shielded (2), flat (2), surrounded (2), conductive (2), help (2), following (2), standards (2), afdx (2), installation (2), mapping (2), geometric (2), describe (2), components (2), barabási (2), centrality (2), matrix (2), community (2), general (2), appearance (2), upload (2), file (2), read (2), english (2), беларуская (2), log (2), account (2), donate (2), menu (2), add, topic, cookie, statement, statistics, developers, conduct, legal, contacts, disclaimers, text, available, under, apply, site, you, agree, registered, trademark, profit, organization, foundation, creative, attribution, sharealike, license, rendered, parsoid, edited, utc, hidden, 2021, webarchive, template, https, org, index, php, title, network_topology, oldid, 1375724157, outline, regulation, bodies, oceania, europe, asia, antarctica, americas, south, north, africa, usenet, toasternet, tanet, npl, janet, internet2, fidonet, cyclades, bitnet, arpanet, notable, uucp, telex, public, ngn, isdn, equipment, store, concepts, orbital, angular, momentum, polarization, multiplexing, exchange, terminal, molecular, vladimir, zworykin, wheatstone, watson, alfred, vail, camille, tissot, nikola, tesla, sumner, tainter, henry, sutton, almon, brown, strowger, shannon, johann, philipp, reis, tivadar, puskás, stepanovich, popov, radia, perlman, grafton, jun, ichi, nishizawa, samuel, morse, antonio, meucci, guglielmo, marconi, innocenzo, manzetti, roberto, landell, hedy, lamarr, narinder, singh, kapany, kao, dawon, kahng, bob, kahn, gardiner, greene, hubbard, harold, hopkins, erna, schneider, hoover, oliver, heaviside, elisha, forest, reginald, fessenden, philo, farnsworth, edison, amos, dolbear, daniel, davis, donald, davies, yogen, dalal, chappe, vint, cerf, walter, houser, brattain, bourseul, jagadish, chandra, bose, francis, blake, tim, berners, emile, berliner, graham, bell, bardeen, paul, baran, logie, baird, mohamed, atalla, edwin, howard, armstrong, nasir, ahmed, whistled, language, videotelephony, teletype, teleprinter, telautograph, smoke, transistor, mosfet, semiconductor, phryctoria, semaphore, radiotelephone, prepaid, photophone, pager, smartphone, mass, age, hydraulic, heliographs, fax, edholm, drums, online, image, dct, audio, compression, protection, beacon, pstn, fabric, arbitrated, hypertree, fat, clos, tetrahedral, resilient, partial, dimensional, campus, tetrahedron, nvidia, farrel, aian, komolafe, olufemi, yasukawa, seisho, february, 2024, scaling, issues, mpls, 5439, bradley, ray, cheltenham, 244, 47869750, 7487, 6147, nelson, thornes, understanding, sosinsky, barrie, indianapolis, wiley, publishing, 359673774, 470, 43131, bible, orosk, com, bicsi, mcgraw, hill, professional, 9780071782968, professionals, 2017, bridging, 1996, january, 2020, webopedia, converters, rs232, annual, international, symposium, blug, bergen, cpip, implementation, laura, acevedo, advantech, ltd, 923, mouser, automation, 303, assignment, 1057, texas, instruments, ten, bulletproof, 12408, jameco, male, female, 25l, awg, 300v, leonardi, mellia, marsan, magazine, wdm, 2019, san, francisco, chiang, mung, yang, michael, 2004, 2013, proc, 42nd, allerton, conference, towards, ities, evolvability, scalability, grant, advances, ethics, igi, xvii, 228, 250, 9781466660595, committee, prqc, alliance, industry, solutions, telecom, glossary, groth, david, toby, skandier, 2005, 7821, 4406, fourth, adjacent, shared, whose, follows, philosophical, assemblage, rhizome, philosophy, simulating, simulation, gradient, schematic, reliability, due, provided, seen, applications, military, multidimensional, instance, toroidal, providing, compensate, limiting, hops, arbitrary, forks, difficult, decentralized, nature, useful, like, messages, reach, alleviate, were, developed, track, identities, during, normal, recording, held, allows, future, forwarded, listening, entire, becomes, rest, viewed, collection, arranged, leaves, regenerators, unlike, functionality, hierarchy, tolerate, own, delayed, plus, generated, means, problems, passive, reduces, probability, applied, traditionally, rebroadcasts, sometimes, linking, isolation, remaining, unaffected, supercomputing, top500, depending, spine, hyperscale, centers, torus, shaped, edges, snowflake, mau, centralized, multistation, combine, resulting, exhibit, topologically, produced, redundancy, expense, complexity, impractical, doesn, quadratically, exponent, assuming, groups, approximated, reed, bottlenecked, weakest, connectivity, workstations, better, closed, direction, repeat, strong, peer, relationship, servers, unable, severs, after, composed, spokes, stacked, differs, although, texts, distinction, extends, extend, allow, greater, would, overcome, considered, simplicity, primary, represents, bottleneck, clusters, workstation, peripherals, resemble, classified, traverses, acts, created, branches, functions, share, reflected, back, causing, unwanted, terminated, terminator, containing, machines, finds, recipient, accepts, match, portion, ignored, less, savings, offset, managing, additionally, dependent, transferred, accessed, connectors, transmitted, trunk, formed, half, eventually, alternatively, reverse, thereby, ensuring, puts, early, days, except, accomplished, partway, bounces, sequence, take, chaining, unimpeded, potential, expressed, telephony, understand, variations, appears, permanently, child, tin, recognizes, eight, circular, controlling, rules, configured, reject, requests, unrecognized, sources, allowing, recognized, vital, role, play, increase, cyber, attacks, firewall, modulator, demodulator, originally, tailored, give, properties, commonly, subscriber, analog, modulated, carrier, included, datagram, conjunction, forwarding, determine, done, said, black, hole, internetworking, typical, adsl, addressing, levels, term, loosely, well, distribute, frame, involved, rather, thought, learns, associate, unknown, targeted, broadcasts, numerous, facilitating, cascading, datagrams, join, slower, largely, directly, come, connects, collision, unified, segmentation, congested, aggregation, smaller, efficient, obsoleted, modern, tiered, across, ends, require, regenerate, affects, proper, function, limit, row, rule, receives, cleans, unnecessary, noise, regenerates, reformed, side, obstruction, cover, degradation, commercial, kilometer, configurations, 100, optics, tens, hundreds, kilometers, retransmitted, electronic, unique, stored, avoid, conflicts, administers, uniqueness, size, six, reserved, identify, assigned, prefixes, uniquely, assign, institute, engineers, responds, addressed, whole, provides, process, accepting, aerial, circuitry, hardware, accessory, card, lot, built, atm, points, microcontroller, programmable, receiver, transceivers, blocks, nics, concerns, beyond, represented, gateways, arinc, 429, gives, slow, sending, amounts, extending, dimensions, humorous, fool, issued, implemented, real, life, 1149, request, comments, avian, carriers, attempts, transporting, visible, invisible, positioning, limited, defines, flavor, open, wave, divide, region, covered, geographic, areas, antenna, calls, pcs, deflected, atmosphere, stationed, above, equator, orbiting, relaying, 236, 786, geostationary, orbit, resembling, dishes, microwaves, gigahertz, range, stations, spaced, approximately, factor, distinguishing, premium, purchasing, printers, financial, benefit, making, decision, purchase, hard, products, review, restrictions, selections, necessary, employee, needs, override, considerations, glass, carries, pulses, represent, metal, loss, immunity, carry, wavelengths, greatly, rate, trillions, long, carrying, continents, map, submarine, ordinary, insulated, utilized, reduce, billion, utp, stp, ratings, scenarios, electromagnetic, induction, crosstalk, citation, untwisted, effective, especially, metallic, enclosures, rolled, braid, foil, lower, deployed, should, length, constraints, gpib, 422, emc, board, particularly, integrated, spi, printed, boards, traces, existing, gigabit, wiring, itu, buildings, sites, aluminum, insulating, flexible, material, dielectric, itself, insulation, conductors, maintain, characteristic, impedance, 200, 500, orders, roughly, slowest, fastest, adopted, networked, transmits, infrared, family, literature, layers, homepna, contrast, regard, interconnection, cascaded, dual, previously, aircraft, closely, methods, virtual, avionics, duplex, token, mediums, refers, determined, capabilities, desired, exist, examples, found, given, graphically, results, shape, variety, conversely, determines, comparison, vehicles, primarily, sensors, actuators, invariably, depicted, logically, wherein, placement, location, illustrates, how, flows, interconnections, differ, yet, identical, concern, elements, industrial, fieldbusses, scientists, software, topics, lists, sir, epidemic, agent, boolean, dynamics, lfr, benchmark, soft, entropy, blockmodeling, stochastic, block, hyperbolic, hgn, rgg, exponential, ergm, watts, strogatz, fitness, bianconi, albert, erdős, rényi, models, efficiency, modularity, assortativity, clustering, motif, metrics, weighted, labeled, hyper, directed, bipartite, incidence, adjacency, vertex, neighborhood, edge, cycle, component, clique, features, graphs, chip, dependency, spatial, semantic, interdependent, artificial, neural, biological, scientific, collaboration, informational, influence, effect, balance, preferential, attachment, transitivity, homophily, closure, reciprocity, optimization, capital, drawing, controllability, evolution, percolation, contagion, complex, notion, base, encyclopedia, item, projects, printable, version, download, print, export, legacy, parser, get, shortened, here, talk, tiếng, việt, oʻzbekcha, ўзбекча, українська, türkçe, தமிழ், српски, srpski, shqip, slovenčina, simple, සිංහල, русский, română, português, polski, ਪੰਜਾਬੀ, norsk, bokmål, nederlands, मराठी, македонски, latviešu, lombard, 한국어, қазақша, ქართული, 日本語, italiano, bahasa, indonesia, interlingua, magyar, hrvatski, हिन्दी, עברית, گیلکی, galego, gaeilge, français, suomi, فارسی, euskara, español, esperanto, ελληνικά, deutsch, čeština, català, bosanski, brezhoneg, বাংলা, български, тарашкевіца, asturianu, العربية, pages, recent, contribute, current, events, navigation, jump,

Text of the page (random words):
e original twisted pair ethernet using repeater hubs was a logical bus topology carried on a physical star topology token ring is a logical ring topology but is wired as a physical star from the media access unit physically avionics full duplex switched ethernet afdx can be a cascaded star topology of multiple dual redundant ethernet switches however the afdx virtual links are modeled as time switched single transmitter bus connections thus following the safety model of a single transmitter bus topology previously used in aircraft logical topologies are often closely associated with media access control methods and protocols some networks are able to dynamically change their logical topology through configuration changes to their routers and switches links edit further information data transmission the transmission media often referred to in the literature as the physical media used to link devices to form a computer network include electrical cables ethernet homepna power line communication g hn optical fiber fiber optic communication and radio waves wireless networking in the osi model these are defined at layers 1 and 2 the physical layer and the data link layer a widely adopted family of transmission media used in local area network lan technology is collectively known as ethernet the media and protocol standards that enable communication between networked devices over ethernet are defined by ieee 802 3 ethernet transmits data over both copper and fiber cables wireless lan standards e g those defined by ieee 802 11 use radio waves or others use infrared signals as a transmission medium power line communication uses a building s power cabling to transmit data wired technologies edit fiber optic cables are used to transmit light from one computer network node to another the orders of the following wired technologies are roughly from slowest to fastest transmission speed coaxial cable is widely used for cable television systems office buildings and other work sites for local area networks the cables consist of copper or aluminum wire surrounded by an insulating layer typically a flexible material with a high dielectric constant which itself is surrounded by a conductive layer the insulation between the conductors helps maintain the characteristic impedance of the cable which can help improve its performance transmission speed ranges from 200 million bits per second to more than 500 million bits per second itu t g hn technology uses existing home wiring coaxial cable phone lines and power lines to create a high speed up to 1 gigabit s local area network signal traces on printed circuit boards are common for board level serial communication particularly between certain types of integrated circuits a common example being spi ribbon cable untwisted and possibly unshielded has been a cost effective medium for serial protocols especially within metallic enclosures or rolled within copper braid or foil over short distances or at lower data rates several serial network protocols can be deployed without shielded or twisted pair cabling that is with flat or ribbon cable or a hybrid flat and twisted ribbon cable should emc length and bandwidth constraints permit rs 232 8 rs 422 rs 485 9 can 10 gpib scsi 11 etc twisted pair wire is the most widely used medium for all telecommunication citation needed twisted pair cabling consists of copper wires that are twisted into pairs ordinary telephone wires consist of two insulated copper wires twisted into pairs computer network cabling wired ethernet as defined by ieee 802 3 consists of 4 pairs of copper cabling that can be utilized for both voice and data transmission the use of two wires twisted together helps to reduce crosstalk and electromagnetic induction the transmission speed ranges from 2 million bits per second to 10 billion bits per second twisted pair cabling comes in two forms unshielded twisted pair utp and shielded twisted pair stp each form comes in several category ratings designed for use in various scenarios 2007 map showing submarine optical fiber telecommunication cables around the world an optical fiber is a glass fiber it carries pulses of light that represent data some advantages of optical fibers over metal wires are very low transmission loss and immunity from electrical interference optical fibers can simultaneously carry multiple wavelengths of light which greatly increases the rate at which data can be sent and helps enable data rates of up to trillions of bits per second optic fibers can be used for long runs of cable carrying very high data rates and are used for undersea communications cables to interconnect continents price is a main factor distinguishing wired and wireless technology options in a business wireless options command a price premium that can make purchasing wired computers printers and other devices a financial benefit before making the decision to purchase hard wired technology products a review of the restrictions and limitations of the selections is necessary business and employee needs may override any cost considerations 12 wireless technologies edit personal computers are very often connected to networks using wireless links main article wireless network terrestrial microwave terrestrial microwave communication uses earth based transmitters and receivers resembling satellite dishes terrestrial microwaves are in the low gigahertz range which limits all communications to line of sight relay stations are spaced approximately 50 km 30 mi apart communications satellites satellites communicate via microwave radio waves which are not deflected by the earth s atmosphere the satellites are stationed in space typically in geostationary orbit 35 786 km 22 236 mi above the equator 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 radio and spread spectrum technologies wireless local area networks use a high frequency radio technology similar to digital cellular and a low frequency radio technology wireless lans use spread spectrum technology to enable communication between multiple devices in a limited area ieee 802 11 defines a common flavor of open standard wireless radio wave technologies known collectively as wi fi 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 ip over avian carriers was a humorous april fool s request for comments issued as rfc 1149 it was implemented in real life in 2001 13 extending the internet to interplanetary dimensions via radio waves the interplanetary internet 14 both cases have a large round trip delay time which gives slow two way communication but does not prevent sending large amounts of information nodes edit main article node networking network nodes are the points of connection of the transmission medium to transmitters and receivers of the electrical optical or radio signals carried in the medium nodes may be associated with a computer but certain types may have only a microcontroller at a node or possibly no programmable device at all in the simplest of serial arrangements one rs 232 transmitter can be connected by a pair of wires to one receiver forming two nodes on one link or a point to point topology some protocols permit a single node to only either transmit or receive e g arinc 429 other protocols have nodes that can both transmit and receive into a single channel e g can can have many transceivers connected to a single bus while the conventional system building blocks of a computer network include network interface controllers nics repeaters hubs bridges switches routers modems gateways and firewalls most address network concerns beyond the physical network topology and may be represented as single nodes on a particular physical network topology 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 the nic responds to traffic addressed to a network address for either the nic or the computer as a whole in ethernet networks each network interface controller has a unique media access control mac address usually stored in the controller s permanent memory to avoid address conflicts between network devices the institute of electrical and electronics engineers ieee maintains and administers mac address uniqueness 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 signal cleans it of unnecessary noise and regenerates it the signal may be reformed or retransmitted at a higher power level to the other side of an obstruction possibly using a different transmission medium so that the signal can cover longer distances without degradation commercial repeaters have extended rs 232 segments from 15 meters to over a kilometer 15 in most twisted pair ethernet configurations repeaters are required for cable that runs longer than 100 meters with fiber optics repeaters can be tens or even hundreds of kilometers apart repeaters work within the physical layer of the osi model that is there is no end to end change in the physical protocol across the repeater or repeater pair even if a different physical layer may be used between the ends of the repeater or repeater pair 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 g the ethernet 5 4 3 rule a repeater with multiple ports is known as hub an ethernet hub in ethernet networks a usb hub in usb networks usb networks use hubs to form tiered star topologies ethernet 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 local bridges directly connect lans remote bridges can be used to create a wide area network wan link between lans remote bridges where the connecting link is slower than the end networks have largely been replaced with routers wireless bridges can be used to join lans or connect remote devices to lans 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 16 a switch is distinct from a hub in that it only forwards the frames to the physical ports involved in the communication rather than all ports connected it can be thought of as a multi port bridge 17 it learns to associate physical ports to mac addresses by examining the source addresses of received frames 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 multi layer switches are capable of routing based on layer 3 addressing or additional logical levels the term switch is often used loosely to include devices such as routers and bridges as well as devices that may distribute traffic based on load or based on application content e g a web url identifier 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 a router uses its routing table to determine where to forward packets a destination in a routing table can include a black hole because data can go into it however no further processing is done for said data i e the packets are dropped modems edit 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 firewalls edit 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 classification edit the study of network topology recognizes eight basic topologies point to point bus star ring or circular mesh tree hybrid or daisy chain 18 point to point edit main article point to point telecommunications the simplest topology with a dedicated link between two endpoints easiest to understand of the variations of point to point topology is a point to point communication channel that appears to the user to be permanently associated with the two endpoints a child s tin can telephone is one example of a physical dedicated channel using circuit switching or packet switching technologies a point to point circuit can be set up dynamically and dropped when no longer needed switched point to point topologies are the basic model of conventional telephony the value of a permanent point to point network is unimpeded communications between the two endpoints the value of an on demand point to point connection is proportional to the number of potential pairs of subscribers and has been expressed as metcalfe s law daisy chain edit daisy chaining is accomplished by connectin...