What is a switch and why do you need such an attachment? Fundamentals of bridges and switches What is a lan switch

The commutator is one of the most important outbuildings that are victorious when local lines. In these articles, we can talk about how switches are used and are based on important characteristics, which is necessary to protect when choosing a switch of a local network.

On the back, we can look at the overall structural scheme, abi to understand how the commutator borrows space from the local enterprise.

The widest one is shown on the little one block diagram small local area. As a rule, such local networks have access switches.

Access switches without intermediary connection to end-of-line networks, giving them access to local resources.

However, the great local networks of commutators have the following functions:

Riven access to the border. As it was assigned more switches and access to give access points to the attachments kіntsevogo koristuvach. At great local networks, the frames of the access switches are not interchanged one by one, but are transmitted through the switches to the distribution.

Riven rozpodіlu. The switches of this level transfer traffic between the access switches, but in case of this they do not interact with the terminal boxes.

System kernel riven. Attachments of this type combine data transmission channels of types of commutators equal to subdividing great territorial local barriers and provide even higher security of switching data flows.

The switches are:

Non-kerned switches. These are the main autonomous extensions in the local area, so as to manage the transfer of data independently and not to be able to dodatkovy nalashtuvannya. Due to the ease of installation and low price, a wide width was created for installation in home minds and small businesses.

Kerovani commutators. Bigger slips and expensive outbuildings. Allow the administrator of the merezhі to independently adjust their tasks.

Kerovany switches can be fixed in one of the following ways:

Through the console port Via WEB interface

Through Telnet Via SNMP protocol

Through SSH

equal switches

All switches can be divided into different models OSI . The commutator may be able to do this with greater possibilities, however, the versatility of yoga will be significant.

Switch 1 equal (layer 1). Before given equal you can add habi, repetitions and other attachments that are physically practiced. The buildings were built on the cob for the development of the Internet and at the given hour in the local area do not win. Otrimavshi signal attachments of this type, just transmit yogo far away, at all ports, Crimean ports

Commutators 2 equals (layaer2). Up to which level one can see non-ceramized that part of the ceramic commutators ( switch ) working on the channel equal model OSI . Switches of another equal work from frames - frames: a stream of data broken into portions. Having taken the frame of the switch equal 2, change the frame to the address of the manager and enter it in your table MAC address, setting this address to the port on which wine the frame was taken. For such an approach, the switches of another equal send data only to the port of the owner, not working with their excess traffic on other ports. Switches of another equal do not know IP address of placement on the third twill line model OSI that practice is less on the canal level.

Switches of another peer support the following widest protocols, such as:

IEEE 802.1 q or VLAN virtual local networks. This protocol allows, within the framework of one physical dimension, to create other logical dimensions.

For example, add-ons are connected to one switch, but they can be found in different VLAN not to chat one to one and transfer data can only be done at your own wide domain (attachments from these VLANs). Between themselves, the computers for the little one can more easily transfer data for an additional outbuilding, which works on the third equal. IP addresses: router.

IEEE 802.1p (Priority tags ). This protocol is present at the protocol IEEE 802.1 q and 3 bit field from 0 to 7. The Danish protocol allows marking and sorting all traffic according to the level of importance and prioritization (maximum priority is 7). Framey with great priority to overcome us in front.

IEEE 802.1d spanning tree protocol (STP).This protocol vibudovuє local merezh in a tree-like structure, schob niknut zakіltsovuvannya merezha and zapobigt storm of the tiring.

It is permissible to install local chimneys at the sight of the ring to increase the resistance to the top of the system. The switch with the highest priority in the merezhі is selected as the root (Root).At the butt of the induced SW3, it is rooted. Not zagliblyuyuchis at algorithms vikonanny protocol, commutators calculate the way from the maximum price and block yoga. For example, in our case, the shortest path from SW3 to SW1 and SW2 will be through the power interface (DP) Fa 0/1 and Fa 0/2. In this case, the price for the promotion for the 100 Mb/s interface will be 19. The Fa 0/1 interface of the switch SW1 of the local network will be blocked by the fact that the price for the route will add up for two transitions between 100 Mb/s interfaces 38+19=19.

Even though the working route will be broken, the commutators will clear the way and unblock the whole port

IEEE 802.1w Rapid spanning tree protocol (RSTP).Enhancements 802.1 standard d , which may be more high stability and less hour of renewal of the line zv'yazku.

IEEE 802.1s Multiple spanning tree protocol.The rest of the version, like a vrakhovu all the shortcomings of the protocols STP and RSTP.

IEEE 802.3ad Link aggregation for parallel link.This protocol allows to unite porti groups. The total dryness of this port of aggregation is formed from the sum of the dryness of the skin port in it.The maximum speed is set by the IEEE 802.3ad standard and is 8 Gb/s.

Switchers 3 equals (layer3). These attachments are also called multiswitches so that they stink at their own commutators, which work on another level and routers, which work with IP packages to the third equal.Level 3 switches cover all functions and standards of level 2 switches. Third devices can handle IP addresses. The switch 3 equals to support the installation of various devices: l 2 tp, pptp, pppoe, vpn etc.

Commutators 4 rubles (Layer 4) . Attachment level L4 models, which work on the transport level OSI . Ensure the reliability of transmission. Qi switches can on the basis of the information from the headers in the packets to understand the belonging of the traffic life supplements and make a decision about redirecting such traffic to the substantiation of this information. The name of such outbuildings did not stand up, and sometimes they are called intelligent switches or L4 switches.

Main characteristics of commutators

Number of ports. In the given hour, switchers are installed with a number of ports from 5 to 48. Depending on this parameter, a number of outbuildings can be deposited, so you can connect to a switch.

For example, with a small local network of 15 computers, we need a switch with 16 ports: 15 to connect the end of the extension and one to install that router connection to access the Internet.

Data transmission speed. Tse shvidk_st, de pratsyuє leather port of the switch. Sound the speed as follows: 10/100/1000 Mb/s. The speed of the work and the port is determined by the process of auto service with the end of the building. For kerosene switches, this parameter can be adjusted manually.

For example: Client attachment of a PC with a 1 Gb/s mesh board connected to the switch port with a 10/100 Mb/s operating speed c . As a result of the automobile service, the house will be built to achieve the maximum possible speed of 100 Mb/s.

Auto service to the port mizh Full - duplex and half - duplex. Full-duplex: the transfer of data is immediately zdіysnyuєtsya at two straight lines. half-duplex the transfer of data is carried out sequentially in one, then in the other directly sequentially.

Internal throughput capacity switching matrix. This parameter shows, with some kind of wild code, the switch can process data from the other ports.

For example: a local network has a commutator for some 5 ports, which works on the speed of 10/100 Mbit/s. AT technical characteristics parameter switching matrix is ​​more expensive 1 Gbit/ c . This means that the skin port is in mode. Full-duplex you can use 200 Mbit/ c (100 Mb/s up and 100 Mb/s up). It is possible that the switch matrix parameter is less than the specified one. This means that at the time of peak demand, porters cannot work out of the declared speed of 100 Mb/s.

Auto fit MDI/MDI-X cable type. This function allows you to designate in two ways the bula is wrapped in a twisted pair of EIA/TIA-568A or EIA/TIA-568B. When installing local lines of the largest width, the EIA / TIA-568B scheme was installed.

Stacking - Tse uniting a number of commutators into one single logical attachment. Different types of switch makers use their own technologies for stacking, for example c isco vicorist stacking technology Stack Wise from bus between switches 32 Gb/s and Stack Wise Plus from bus between switches 64 Gb/s.

For example, this technology is relevant for large local networks, it is necessary to connect more than 48 ports on the basis of one building.

Fixing for 19” rack. In home minds and small local fencing, the switches are often installed on even surfaces or fastened to the wall, the presence of the so-called “wuh” is necessary in large local fencing and is actively located in server closets.

MAC Table Dimensionaddress. The commutator (switch) is attached, which works on 2 equal models. OSI . On the hub view, which simply redirects the frame from all ports to the port of the port, the switch starts: remember MAC I will add a porter to the address, bringing it in, I will write down the port number and hour of life to the table. With this table, the switch redirects the frame not to all ports, but only to the master port. As in the local area, the number of outbuildings significantly increases the number of reordering tables, the commutator starts to overwrite the old entries in the tables and writes new ones, which significantly reduces the speed of the commutator's operation.

jumbo frame . This function allows the switch to work with a larger packet size, lower is designated by the Ethernet standard. After receiving the skin pack, one hour is spent on yoga. If you win a larger packet size using Jumbo Frame technology, you can save for an hour the processing of a packet in mergers, de-bouncing the speed of data transfer to 1 Gb / s and more. For less speed, I won't win the great

Switching modes.In order to understand the principle of robotic switching modes, let's take a look at the structure of the frame that is transmitted on the channel line between the borders and by the switch at the local border:

As can be seen from the little one:

• The start of the preamble signals the start of the transfer to the frame,
• Potim MAC recognition addresses ( DA) and MAC addresses of the source ( SA)
• Third level identifier: IPv 4 or IPv 6 win
payload)
• І nasamkinets control sum FCS: 4 byte CRC value, which is used to detect transmission pardons. Calculated by the party that rules and is placed in the FCS field. The receiving party calculates given value independent and similar to the otrimanim meanings.

Now let's look at the switching modes:

Store-and-forward. This switching mode takes the frame from the buffer over and overrides the field FCS , as it is located on the very end of the frame, and as the control sum of the field does not run, the entire frame is displayed. As a result, the amount of time spent on vanishing at the border is reduced, so that it is possible to send a frame with a pardon, and to change the hour of the packet transfer. Given technology present in road commutators.

cut through. Simple technology. AT to this particular type frames can be processed more quickly, so that they do not need to buffer more. For analysis, data is taken into the buffer from the beginning of the frame up to the recognition MAC address (DA) inclusive. The switch reads the MAC address and redirects to the destination. Not enough given technologies and those that the commutator overpowers at times as dwarf, less than 512 bit intervals, and slower packets, increasing the burden on the local network.

Support for PoE technology

Pover over ethernet technology allows you to power an external device over that cable. Decision allows you to spend pennies on additional installation of line living.

There are also PoE standards:

PoE 802.3af supports power up to 15.4W

PoE 802.3at supports power up to 30W

Passive PoE

PoE 802.3 af/at may have intelligent control circuits for power supply to attachments: the first lower power supply to the attachments PoE dzherelo standard af/at vyroblya uzgodzhennia with it, so that it can be protected from the attachment. Passiv PoE is significantly cheaper than the first two standards mesh cable without any weather.

Characteristics of standards

The PoE 802.3af standard is supported by most inexpensive IP video cameras, IP telephones and access points.

The PoE 802.3at standard is present in the expensive models of IP cameras, video warning, it cannot be invested in 15.4 watts. I have an IP video camera, so I have a PoE (switch) to comply with this standard.

Extension slots. The switches can have additional expansion slots. The most expandable are SFP modules (Small Form-factor Pluggable). Modular, compact receivers that are designed to transmit data to a telecommunication medium.

SFP modules are inserted at the right port of the SFP router, switch, multiplexer or media converter. Want to install SFP Ethernet modules, usuallyfiber optic modules are used to connect to the main channel when transmitting data on large distances, inaccessible to the Ethernet standard. SFP modules are selected depending on the security of data transmission. The most wide-ranging are dual-fiber SFP modules, which use one fiber to receive, otherwise transmit data. However, WDM technology makes it possible to transmit data on different devices over a single optical cable.

SFP modules are:

• The SX-850 nm is wired with a multi-modal optical cable for a distance of up to 550m.
• LX - 1310 nm works with both types of optical cable (SM and MM) for distances up to 10 km.
• BX - 1310/1550 nm works with both types of optical cable (SM and MM) for distances up to 10 km.
• XD - 1550 nm wiping with single-mode cable up to 40 km, ZX up to 80 km, EZ or EZX up to 120 km and DWDM

The SFP standard itself transmits data transmission with a speed of 1Gb/s or with a speed of 100 Mb/s. For more data transfers, SFP+ modules have been expanded:

• SFP+ data transmission with 10 Gb/s speed
• XFP data transfer with 10 Gb/s speed
• QSFP+ data transmission with 40 Gb/s
• CFP data transfer with 100 Gb/s speed

However, at higher speeds, signal processing is carried out high frequencies. Tse will require more heat and, apparently, large dimensions. Therefore, Vlasne, the SFP form factor was saved from SFP + modules.

Visnovok

A lot of chitachiv singsongly clung to non-ceramic switches and budgetary ceramic switches of a different level in small local areas. However, the selection of commutators to encourage greater and technically foldable local lines is better given to professionals.

Bezpechna Kuban for an hour of installation of local networks of vicorist switches and offensive brands:

Professional solution:

Cisco

Qtech

Budget solution

D-Link

Tp Link

Tenda

Bezpechna Kuban vykonuє installation, commissioning and maintenance of local lines in Krasnodar and Pivdnі Russia.

Food and drink to encourage local networks to be presented to koristuvachs-nefahіvtsy more collapsible through the great terminological dictionary. Khabi and switches are painted in the folded hands, which guess telephone exchange and the creation of a local home network becomes a drive for bringing to fahіvtsіv. Actually, it’s not such a terrible switch, as it’s called: the attachments are elementary nodes of the mesh, which allow for minimal functionality, which does not impair the knowledge of how the operation is installed and is fully accessible to the skin.

Appointment

Hub- Merezhey concentrator, the purpose of connecting computers to a single local network with additional connection of Ethernet cables.

Switch(switch - jumper) - fencing switch assignments for local networking of a number of computers via an Ethernet interface.

Porivnyannia

As a matter of fact, the difference between a hub and a switch is tied to the type of outbuildings: a hub and a switch. Irrespective of one task - the organization of a local network for the help of Ethernet - I will go to the top in a different way. The hub is the simplest rozgaluzhuvachem, which ensures direct communication between the customers of the city. The switch is a sensible attachment that distributes packages of data between clients in advance of the request.

The hub, holding a signal from one node, transmits it to all connected attachments, and then receives it again as a destination: the computer is to blame for recognizing the packet itself. Zvichayno, vidpovіd transferring the same scheme. The signal torkaetsya all segments in the line, until you know which one to accept. Tsya furnishing reduces the throughput of the building of the merezhі (and the security of the exchange of data is clear). The switch, otrimuyuchi data package from the computer, sends it to itself for your address, as the bula was set by the manager, allowing for the least amount of traffic. Merezha, organized for the help of the switch, is important for safety: traffic exchange is carried out without intermediary between two clients, the other one cannot process the signal, there are no appointments. At the front of the hub, the switch secures the high throughput of the building of the created barrier.

Hub Logitec LAN-SW/PS

Switch Vimaga correct alignment client-computer's map: IP addresses and the mask of the dmérée façade match one to one (the dmérée mask specifies part of the IP address as the address of the measure, and the other part as the address of the client). The hub does not help, to that, which works on the physical OSI mesh model, broadcasting the signal. The switch works on the channel channel, allowing the exchange of data packets. Another feature of the hub is the ability to ensure the speed of transmission of data, focusing on the best displays.

Visnovki site

1. A hub is a hub, a switch is a switch.
2. The hub is the simplest, the switch is more "intellectual".
3. The hub transmits a signal to all the clients of the merezhі, the switch - only to the addressee.
4. Productivity of a measure organized through a switch, vishcha.
5. The switch ensures the highest level of safe transmission.
6. The hub is based on the physically tethered OSI model, the switch is on the channel.
7. Switch to ensure correct alignment mesh cards customers.

03/18/1997 Dmitro Ganzha

The commutators occupy the central space of the modern local networks. TYPES OF SWITCHES HUB RISC AND ASIC PACKET PROCESSING ARCHITECTURE OF HIGH-CLASS SWITCHES modern technologies.

The commutators occupy the central space of the modern local networks.

Switching is one of the most popular modern technologies. Switches connect bridges and routers to the periphery of local networks, depriving them of the role of organizing communication through the global network. Such popularity of commutators is slandered in pershu tim, that they allow for micro-segmentation rahunok to increase the productivity of the meshes in porous meshes that are divided, with the same nominal throughput building. Krim podіlu merezhі on drіbnі segments, commutators give the possibility to organize plug-ins in a logical array and easily regroup them, if necessary; otherwise, apparently, they allow you to create virtual measures.

What is a commutator? Згідно з визначенням IDC, "комутатор - це пристрій, конструктивно виконаний у вигляді концентратора і діє як високошвидкісний багатопортовий міст; вбудований механізм комутації дозволяє здійснювати сегментування локальної мережі та виділяти смугу пропускання кінцевим станціям в мережі" (див. статтю М. Кульгіна "Побудувати мережу plant a tree..." at the lute room LAN). However, the appointment is carried out by us in front of the commutators of personnel.

TYPES OF COMMUTATION

Under the commutation, sound out the minds of different technologies - configuration commutation, commutation of personnel, commutation of middle and middle ones, and transformation between personnel and middle ones.

The home switching configuration is the same as the port switching, and a specific port on the smart hub module is assigned to up to one of the internal Ethernet segments (or token ring). Tse recognition zdiisnyuetsya in the distant rank for help program management merezhey when connected or moved koristuvachiv and resources at the merezha. On the basis of other switching technologies, this method does not increase the productivity of local networks.

Frame switching or switching in a local network using standard Ethernet frame formats (or Token Ring). The skin frame is processed by the nearest commutator and transmitted further through the mesh without interruption. As a result, the merging transforms like a bi into a collection of parallel high-profile straight channels. Those, how the commutation of personnel in the middle of the commutator, is easier to look at below on the butt of the concentrator, which are commutated.

Intermediate switching is done in ATM. Vykoristannya small average fixed life gives the opportunity to create inexpensive high-speed switching structures on the hardware level. І staff commutators, and mid-range commutators can support a small number of independent working groups independently from their physical connection (div. division "Pobudova virtual networks").

Interchange between frames and in the middle allows, for example, stations with an Ethernet board to interact without intermediary with ATM devices. Tsya tekhnologiya zastosovuetsya pіd hаmіlії ї ї ї ї ї ї rezhі.

At this school, we are in front of the staff commutation.

SWITCHING HUB

The first switching hub, called EtherSwictch, was presented by Kalpana. This concentrator allowed to reduce the competition among the merchants for the speed of the number of knots in the logical segment for the help of micro-segmentation technology. In fact, the number of stations in one segment was shortened to two: the station that initiated the request, the station that confirmed the request. No other station will not process information that is transmitted between them. Packets are transmitted across the bridge, but without the power of the bridge zatrimki.

At commutations Ethernet networks a skin member of the group with a few coristuvachs can be guaranteed an hourly bandwidth of 10 Mbit/s. To understand how such a concentrator works, the most helpful analogy from the great old telephone switchboard, for which participants in the dialogue are coaxial cable. If the subscriber calls on the "permanent" 07 and asks for a call with such a number, the operator first checks for everything, which line is available; if so, then vin z'ednuvat uchasnikiv without intermediary for the help of the cable cable. Nobody else (behind the vinnyatka of the special services, zrozumіlo) was not able to rozmov a little bit. After completion of the move, the operator opened the cable to both ports and check for the next week.

Switching hubs is similar (div. Figure 1): they transfer packets from the input port to the output port through the switching matrix. If a packet is sent to an input port, the switch reads its MAC address (that is, the address of another equal), and it is redirected to the port that matches that address. As a port of employment, then the package is sent to the black. In fact, it is a buffer on the input port, de packets are checked, if the required port is called. Prote buffering methods are being challenged.

Little one 1.
Switching hubs function similarly to many telephone switches: they plug the inlet port directly with the outgoing through the switching matrix.

PACKAGE PROCESSING METHODS

In case of cross-connection (also called switching on the fly and switching without intermediate buffering), the switcher reads only the address of the packet to reach. The package is transferred far and wide, depending on the availability of the new pardon. This allows you to significantly speed up the processing of the packet, the shards are read only a little bit of the first bytes. It is the fault of the receiving party that it is the fault of the defective packets and requesting their retransmission. However, modern cable systems are needed, so the need for re-transmission in bags is minimal. Tim is not smaller, there is no insurance against pardons at the time of a broken cable, malfunctions to pay chi shift code from the right electromagnetic dzherel.

When switching with intermediate buffering, the switcher, while accepting a packet, does not transmit further until it has read the rest, otherwise it has not read all the necessary information. Vіn is no longer assigned to the owner's address, but also to check the checksum, i.e. you can find defective packets. Tse allows you to isolate how to generate a pardon segment. In this rank, the commutation with intermediate buffering is deafening to superiority, and not to swiftness.

Krim two perekahovanyh vishche, deyakі commutator vikoristovuyut hybrid method. In savvy minds, the stink of zdіysnyuyut skrіznu commutation, but at the same time, stalking for a few pardons at the sight of rechecking the control sums. If a number of pardons reach a predetermined threshold value, the stink will switch to the switching mode from intermediate buffering. When the number of pardons is reduced to an acceptable level, the stench turns into a direct switching mode. This type of switching is called threshold or adaptive switching.

RISC and ASIC

Most switches from intermediate buffering are implemented on the basis of standard RISC processors. One of the advantages of such an approach is that it is notably cheap compared to switches with ASIC integrated circuits, proteins are no different than those of different specialty add-ons. Switching in such extensions is carried out for additional software, so the functionality can be changed for additional modernization of the installed firmware. It’s not enough for those who stink more for switches based on ASIC.

Switches with ASIC integrated circuits are designed for specialized applications: all of their functionality is "hardwired" in the security hardware. This approach has a shortcoming: if modernization is necessary, the vibration picker will rework the scheme. ASIC sound zdіysnyuyut skrіznu commutation. The ASIC switching matrix creates a physical path between the incoming and outgoing ports, as shown in .

ARCHITECTURE OF SWITCHES IN THE SENIOR CLASS

High-end switches have, as a rule, a modular structure, and stinks can be used both for packet switching and for middle-class switching. Modules of such a commutator zdіysnyuyut commutation between merezhami different types, Including Ethernet, Fast Ethernet, Token Ring, FDDI and ATM. Whereas the main switching mechanism of such attachments is the ATM switching structure. Let's take a look at the architecture of such attachments on the Centillion 100 butt of the Bay Networks company.

Switching is carried out for the help of the advancing three hardware components (div. baby 2):

(1x1)

Figure 2.
In high-end switchers, switching occurs more and more often high speed and ease of migration to ATM.

The skin switch module can port I/O, buffer memory and the CellManager ASIC. In addition, the skin module for local media may have a RISC processor for switching frames between local ports and picking / picking packets for converting frames and midpoints one to one. All modules can independently establish switching between their ports, so only traffic assigned to other modules is transmitted through the connection panel.

The skin module supports its own address table, and the head processor combines them into one global table, so why can an okremium module be able to measure as a whole. For example, if the Ethernet module accepts a packet, it determines to whom the packet is addressed. As the addresses are changed from the local address table, the RISC processor will switch the packet between the local ports. If the addressee is on another module, then the picker / picker will convert the package to the box. The CellManager specifies a destination mask to identify the module(s) and port(s) that are to be assigned to the core target. Skin module, pay mask bit of any destination mass task, copy the middle to the local memory and transfer data to the output port to the specified port mask bit.

ENCOURAGING VIRTUAL MERGE

Crime for increasing productivity, commutators allow you to create virtual networks. One of the methods of creating a virtual network is to create a wide-range domain behind an additional logical port in the middle of the physical infrastructure of the communication extension (it can also be a smart hub - a configuration switch, so a switcher - a switch). For example, unpaired ports of an eight-port outbuilding are assigned to one virtual line, and guys - to another. As a result, the station in one virtual area appears isolated from the stations to the other. The disadvantage of such a method of organizing a virtual fence is that all stations connected to one and the same port are guilty of lying up to one virtual fence.

Another way to create a virtual network is based on the MAC addresses of connected devices. With this method of organizing a virtual network, for example, you can connect your portable computer to a port of the switch, and you will automatically assign the value of the first wire to your other virtual network based on the MAC address. This method also allows shortlisters, connected to one port of the switch, to lie up to different virtual borders. Report about virtual arrays of divs. article by A. Avduevskiy "Such real virtual measures" in the birch LAN issue for this region.

SWITCHING OF THE THIRD RIVNYA

For all their successes, the commutators suffer one stout shortfall: the stench is not able to protect the measure from avalanches of wide packets, but only to the point of unproductive entanglement of the measure and an increase in the hour of the day. Routers can control and filter non-required wide traffic, but stinks can be an order of magnitude better. So, according to the documentation of Case Technologies, the typical productivity of the router is 10,000 packets per second, but the price is not equal to that of the switch - 600,000 packets per second.

As a result, a lot of virobniks began to be introduced into the switcher and the routing functions. If the robot of the commutator did not succeed, there are different methods: for example, switching of another level, and switching of the third level are implemented without intermediary hardware security(In ASIC integrated circuits). Different companies call this technology in different ways, but one meta: the routing switch is guilty of violating the functions of the third level for the same security, which is the function of another level. An important factor is the price of such an addition to the port: it is also due to the low cost, like that of the commutators (div. article by Nick Lipps in the next issue of the LAN magazine).

WISNOVOK

Switches are both structurally and functionally different; in one small article it is impossible to miss all aspects of it. In the coming years, the ATM switcher is reported to be visible.

Dmitro Ganzha is a senior editor at LAN. You can contact him at: [email protected].

Switches in the local area

How to choose a commutator with the necessary variability? Functionality current models even better. You can use the simplest non-certifying switch, as well as a richly functional kerating switch, which is similar to a full-fledged router. As an example of the rest, you can bring Mikrotik CRS125-24G-1S-2HND-IN from the new Cloud Router Switch line. Obviously, the price of such models will be richly rich.

Therefore, when choosing a switch, it is necessary for you to be appointed, as for the functions and parameters of the current switches, you will need, and for which you do not need to overpay. Ale on the cob - trochs of theory.

See the switches

However, even before the kerosene switches were introduced into the non-ceramic ones, including a wider set of functions, then at the same time, the difference may be less for the feasibility and impossibility remote care add on. In another way - to add additional functionality to the simplest model, often increasing their versatility.

Therefore, at once more informative classification of commutators for peers.

equal switches

In order to choose a commutator that is optimally suited to our needs, it is necessary to know its value. This parameter is set on the basis of what the OSI (data transfer) model is based on.

• Attached first equal, what to win physical the transfer of data that is already practically known from the market. If something else is remembered, habi is an example of a physical equal, if information is transmitted by a strong stream.
• Riven 2. Until the new one, practically all non-wired commutators are seen. Vikoristovuetsya so called canal Merezheva model. Attaches add information to other packages (frames, frames), revise them and send them to a specific device-controller. The basis of the distribution of information in switches of another level is MAC-addresses. From them, the switch stores the addressing table, remembering which port the MAC address is given. IP addresses don't stink.

• Riven 3. By selecting such a switch, you will remove the attachments that work with IP addresses. And also to improve the impersonal possibilities of work with danim: the transformation of logical addresses to physical ones, mezhezhі protocols IPv4, IPv6, IPX etc., pptp login, pppoe, vpn and others. On the third merezhe On the level of transmission of data, practically all routers work and most of the commutators are "stuck in".

• Riven 4. Merezheva OSI model, as it is called here transport. Please note that not all routers are available for additional models. Rozpodіl traffic vіdbuvaєtsya on іntelektualnomu pіvnі - prіy vmіє pratsyuvati z dodatki that on pіdstavі titlіvіv poksіv z dannymi їkh sprіbnoyu їх їх prіbnoyu address. In addition, the transport level protocols, such as TCP, guarantee the reliability of packet delivery, saving the sequence of their transmissions and optimizing traffic.

Select switch - read characteristics

How to select a commutator for parameters and functions? Let's look at what is on the verge of deyakim s designations, which are often mentioned, in the characteristics. The basic parameters can be seen:

Number of ports. The number varies from 5 to 48. When choosing a commutator, it is better to transfer the stock of a further extension of the line.

Basic data transmission speed. Most of the time we know 10/100/1000 Mbit/s - security, as I will add a leather port. That is, the Vibranium switch can operate with a speed of 10 Mb/s, 100 Mb/s or 1000 Mb/s. To add a lot of models, which are equipped with gigabit and 10/100 Mb/s ports. Most current switches are based on the IEEE 802.3 Nway standard, automatically adjusting the port speed.

Throughput and internal throughput. The first value, which is also called the switching matrix, is the maximum amount of traffic that can pass through the switch in one hour. Calculation is even simpler: port x port x port x 2 (duplex). For example, an 8-port gigabit switch can have a bandwidth of 16 Gb/s.
The internal throughput of the building is indicated by a picker and it is necessary only to match it with the forward value. As stated, the internal throughput of the building is less than the maximum - it will be bad for you to cope with great adventures, play and hang.

Automatic MDI/MDI-X assignment. Tse avtovyznachennya that podtrimka of both standards, for which the bula is compressed, the pair is twisted, without the need for manual control of the circuit.

Extension slots. Possibility of connecting additional interfaces, for example, optical ones.

Table expansion MAC address. For the choice of the commutator, it is important to advance the necessary expansion of the table, but also to improve the possible expansion of the table. Even though the records on the tables are not fixed, the switcher records new ones on top of the old ones, and therefore the transmission of data is halted.

Form factor. The commutators are available in two different types of housing: floor/wall variant of placement and for rack. Accepted in the rest of the day standard size outbuildings -19 inches. A special ear for fastening at the rack can be removed.

We choose a switcher from the functions we need for work with traffic

Flow control ( flow control, IEEE 802.3x protocol). Transferring the service to the reception-management of data between the annexes, which are managed, and the switchboard in case of high demands, in order to avoid the cost of packets. The function is supported by a skin switch.

jumbo frame- Larger packages. Zastosovuetsya for 1 Gbit / s and more, which allows you to speed up the transfer of data for a change in the number of packets and an hour for their processing. Function є mayzhe at the skin switch.

Full-duplex and Half-duplex modes. Practically all modern lamps support auto-completion between full duplex and full duplex (transfer of data only in one bik, transfer of data in both directions at once), so as to avoid problems with the merezhі.

Traffic prioritization (IEEE 802.1p standard)- add to the list of important packets (for example, VoIP) and overpower them. Selecting a commutator for a network, for some part of the traffic, we add audio or video, varto transfer respect for this function

Pidtrimka VLAN(standard IEEE 802.1q). VLAN is a handy zasіb for separating okremih businessmen: internal lines of business and the lines of out-of-pocket service for clients, and other companies too.

To ensure safety in the middle of the treadmill, to control or re-verify the productivity of the treadmill property, you can turn around (duplicate traffic). For example, all the necessary information is sent to one port for re-verification of the records by the first PZ.

Port forwarding. This function may be needed for opening a server with access to the Internet, or for online igor.

Zakhist in the form of "loops" - STP and LBD functions. Particularly important is the hour of choosing non-ceramic switches. They have a noose that has become established - the Kіltsev dіlyanka merezhі, the reason for the rich glitches and hanging is practically impossible. LoopBack Detection will automatically block the port where the loop was made. The STP protocol (IEEE 802.1d) and this more perfect fit - IEEE 802.1w, IEEE 802.1s - are three times better, optimizing the tree-like structure. On the back at the structure of the transfer of the reserve, the calcification of the needles. For zamovchuvannyam stench included, and the switch starts єx only then, if you want to open the call to the same main line.

Channel Aggregation (IEEE 802.3ad). Increase the throughput of the channel, increasing the number of physical ports into one logical one. The maximum capacity of the building for the standard is 8 Gb/s.

Stacking. A leather maker of vicorist waters of scaling, and at the same time, this function signifies a virtual combination of several commutators into one logical addition. Meta stacking - otrimati Great number portіv, which is possible when using a physical switch.

Switch functions for monitoring and fault diagnosis

A lot of commutators indicate the inadequacy of the cable connection, ring when the outbuilding is turned on, as well as the type of inaccuracy - shaving lived, briefly flickering thinly. For example, D-Link has special indicators on the case:

Virus traffic protection (Safeguard Engine). The technique allows to increase the stability of work and protection central processor Vіd navantazhen "smіtєvim" by traffic of virus programs.

Functions of electric power

Energy saving.How to choose a commutator, which will save you electricity? Get your respecte on the presence of energy saving functions. Actuators, for example D-Link, release commutators from power regulation. For example, a smart switch to monitor connections to a new extension, and even though at the moment none of them work, the port is switched to "sleep mode".

Power over Ethernet (PoE, IEEE 802.af standard). A switchboard with different technologies can be connected to a new extension for pair torsion.

Waking up a lightning guard. The function is also needed, however, remember that the commutators are also connected to the ground, otherwise they will not work.

For the construction of local and home merezhi, you will need special outbuildings. You know a few things about them. I will try to explain it in a simpler way, in order to understand the skin.

Appointment .

Hub (Hub), switch (switch) and router (router) are designed to create a network between computers. It was clear after the creation of a measure of functionality.

Vіdminnіst .

What is a hub (hub)

Hub - tse repeater. Everything that is up to the new one is connected - it will be repeated. One is given to the hub and everything is tied to that.
For example, you connected 5 computers via the Hub. In order to send data from the fifth computer to the first, the data will be sent through all computers in the array. This is similar to a parallel phone - access to your data can be taken by any computer, and you are the same. For the rahunok of which, the vanity is also increased. It seems that the more computers are connected, the better it will be more vanity on the measure. The axis of this in our hour is less and less let out habіv and less and less they are koristuyutsya. Nezabar zovsіm zniknut.

What is a switch?

What is a router?

The router can be twisted as well as: PC -> router -> Internet, and in combination with other attachments: PC -> switch / hub -> router -> Internet.

Another advantage of the router is yoga easy installation. Most of all, you will need less than the minimum knowledge to connect, set up a network and access the Internet.

Otzhe. Pіdіb'yu small pіdbags.

All the annexes are necessary for the construction of the fence. The hub and the switch do not wind up one kind of one. Router - the most necessary better solution for the creation of a fence.