Gigabit Ethernet network. Gigabit ethernet network unshielded twisted pair

I did not hasten to shift my home merezha zі shvidkosti 100 Mbit / s to 1 Gbіt / s, which is wonderful for me to finish, I transfer the shards through the network to a large number of files. However, if I'm spending pennies on computer or infrastructure upgrades, I care that I can take advantage of productivity gains in the add-ons and games I run. Lots of koristuvachiv love to comfort yourself with a new video card, central processor and as a gadget. For some reason, the possession of the land does not attach such enthusiasm. It’s true, it’s easy to put the earned pennies into the merezhna infrastructure as a substitute for a black technological gift for the people’s day.

For the most part, the throughput capacity is too high for me, and at one moment I realized that the infrastructure for 100 Mbit / s is no longer available. All my home computers can already integrate 1 Gb / s adapters (on motherboards), so I’ll take the price list of the nearest computer company and see what I need to transfer all the infrastructure to 1 Gb / s.

Hі, home gigabit merezha zovsіm is not so foldable.

I bought that having installed everything obladnannya. I remember that before copying the great file at 100 Mb/s, it took close to repeating the whiling. After upgrading to 1 Gb / s, the same file became copied in 40 seconds. The increase in productivity was pleasing, but still I didn’t take away ten times the gain, as it was possible to estimate the equal bandwidth of 100 Mb / s and 1 Gb / s of the old and new merezh.

What is the reason?

For a gigabit measure, the third part of the charge is to add 1 Gb/s. For example, if you have installed gigabit mesh cards and power cables, and if the hub/switch supports a total of 100 Mb/s, then the whole mesh will work at 100 Mb/s.

Persha Wimoga is a fencing controller. The best, as a leather computer, will be equipped with a gigabit network adapter motherboard). Qiu can be satisfied with the simplest, most of the choices of motherboards and the rest of the world integrate gigabit controllers.

A friend of the better is a merezhna card that can support 1 Gb / s. The pardon has been expanded, that for gigabit networks a cable of category 5e is required, but in fact, the old Cat 5 cable supports 1 Gb/s. Wm, Cat 5e cables can be shortest characteristics That stench will be more optimal solution for gigabit networks, especially as the length of the cables will be decent. Wt_m, Cat 5e cables today are all the same found, remnants of the old Cat 5 standard are already outdated. New Cat 6 road cables may offer even better performance for gigabit networks. We compare the performance of Cat 5e vs. Cat 6 cables three times better than ours.

The third and, unmistakably, the most expensive component of the gigabit network is the hub/switch of 1 Gb/s. Obviously, it’s better to use a switch (possibly, in a pair with a router), an oscillating hub or a hub - not the most intelligent attachment, which simply broadcasts all the data on all available ports, which leads to the appearance of a large number of calls and an increase in the productivity of the network. If you need a high level of productivity, then you can’t do without a gigabit switch, the shards of the vins redirect the network data only to the required port, which effectively increases the speed of the work and the network connected with the hub. The router should ring out at the next switch (from the kіlkom LAN ports), and also allows you to connect your home network to the Internet. The greater number of home coristuvachs will explain the benefits of a router, so a gigabit router is a variant of many advantages.

Entry

Merezhі on the basis of 10/100 Mbit/s Ethernet will be more and more sufficient for vikonannya, whether it be zavdan at small merezha. How about some future? Have you thought about the streams of video that pass through the fence of your booth? Chi vporaetsya with them 10/100 Ethernet?

In the first article, assigned to gigabit Ethernet, we are familiar with it, and it is significant that it is necessary for you. We will also try to find out what you need to create a "ready to gigabyte" measure and we will conduct a short tour of a gigabyte property for small businesses.

What is Gigabit Ethernet?

Gigabit Ethernet is also known as "gigabit over midi" or 1000BaseT. Vіn є zvchaynyy version of Ethernet, scho pratsyuє on shvidkosti up to 1.000 megabits per second, that's ten times faster than 100BaseT.

The basis of gigabit Ethernet is the IEEE standard 802.3z, a kind of hardening in 1998 roci. However, in the red 1999 year, an addition was made to the new one - the standard for gigabit Ethernet over a copper twist pair 1000BaseT. The very standard could introduce gigabit Ethernet from server rooms and backbone channels, ensuring that it was crowded in the same minds as 10/100 Ethernet.

Before the advent of 1000BaseT for gigabit Ethernet, it was necessary to use fiber optic or shielded copper cables, which can hardly be called handy for laying cables. local mesh. These cables (1000BaseSX, 1000BaseLX and 1000BaseCX) and today are victorious in special areas of congestion, so we will not consider them.

The Gigabit Ethernet 802.3z group miraculously ran into its work - it released a universal standard that outweighed the speed of 100BaseT tenfold. 1000BaseT also sum back s 10/100 CAT-5 cable (or I'm looking for a category). To the point, today the standard mesh is designed by itself on the basis of the cable of the fifth category.

What is the wine we need?

In the first literature about gigabit Ethernet, the corporate market has become a standard for the new standard, and most of all, the link to data collections. Small gigabit Ethernet secure ten times the channel, lower 100BaseT, natural congestion standard I will pass the building. Tse zv'yazok mizh servers, switches and backbone hubs. Gigabit Ethernet itself is required, required and costly.

In the world, price reduction per gigabit, the area of ​​1000BaseT occupancy has expanded to computers "advanced coristuvachiv" and working groups, like vicorist "vibrating to the bandwidth of the program."

Oscilki need to transfer data from more small companies, more modest ones, hardly if they ever need a pass for 1000BaseT buildings. Let's take a look at some typical areas of small-sized networks that are estimated to be required by gigabit Ethernet.

Chi we need wine for us, prodovzhennya

• Transferring large files through a measure

  Similar zastosuvannya is typical, especially for small offices, especially in companies that are engaged in graphic design, architecture or other business, tens-hundreds of megabytes are used to process files. You can easily guess that a 100 MB file will be transferred over 100BaseT in less than a few seconds [(100 MB x 8 bit/byte)/100 MB/s]. Indeed, there are a lot of officials to improve the speed of the transfer, so your file will be transferred three times longer. Activities operating system, running programs, the amount of memory on your computers, the speed of the processor and the century. (Vіk system vplivaє shvidkіst tires on the motherboard).

  Another important factor is the portability of the terrestrial possession, and the transition to gigabytes of occupancy allows you to use the potential of the university space and speed up the transfer of great files. It is rich to confirm that the adoption of data rates is higher than 50 Mbit / s on 100BaseT networks - on the right, it is by no means trivial. Gigabit Ethernet can provide a throughput capacity of more than 100 Mb/s.

• Merezhevі pristroi reservation

  You can look at this view as a variant of the great files. Since the network is configured to back up all computers to one file server, gigabit Ethernet will allow you to speed up the process. However, here there is a water stone - an increase in the "pipe" of the bandwidth to the server may not lead to a positive effect, as the server cannot be able to process the input data stream (it also costs to carry and carry backup information).

  To take advantage of high-speed storage, you should equip the server with a great memory and make a backup on the high-speed hard drive, not a line on the CDROM. Like Bachimo, before the transition to gigabit Ethernet, the next step is to prepare.

• Program client-server

  Tsya sphere of zastosuvannya again is more typical for small businesses, less for home businesses. Between a client and a server in similar programs, a great deal of data can be transmitted. Pіdkhіd kolishnіy: you need to analyze the amount of data that is being transferred, in order to find out, so that the program can “catch up” for the increased throughput of the building and that there is enough data for the gigabit Ethernet traffic.

It seems true, we vvazhaemo, that it is unlikely that most of the "budvelniki" home funds know enough to buy a gigabit property. In small businesses, switching to gigabit can help, but we recommend that you first analyze the amount of data that is being transferred. From the current camp, everything made sense. Alas, be shy, as if you are trying to protect the possibility of future modernization. What do you need to work today, so that we can cook before it? At the offensive part of our stats, we can look at the change, as it is necessary to improve with the most expensive, most often and most laborious part of the line. cable.

Gigabit Ethernet cable

As we have already guessed at the entrance, one of the key ones could be the 1000BaseT standard and the cable category 5 (CAT 5) or more. Tobto Gigabit Ethernet can apply to the basic cable structure of the 5th category. Wait a minute, such a possibility is already lucrative. As a rule, all current strands are wired with a cable of the fifth category, as your strand was not installed in 1996 or earlier (the standard was approved in 1995). However, here іsnuє sprat of underwater stones.

• You need to bet

  Yak can be seen from tsієї statti, 1000BaseT cable to all pairs of cable category 5 (or more) for the connection of 250 Mbit / s channels. (Also, another coding scheme will be installed - p'yatir_vneva amplitude-pulse modulation - to get stuck in the boundaries frequency range 100 MHz (CAT5). As a result, we can win for gigabit Ethernet the basic CAT 5 cable structure.

  Oskіlki 10/100BaseT win only two bets CAT 5 іz chotirioh, deyakі people did not connect the bid bet for an hour laying their treasury. The bets were made, for example, for telephone or Ethernet (POE). Fortunately, gigabit cards and commutators may have enough intelligence to comply with the 100BaseT standard, so all bets will be unavailable. That's why your merging, in any case, is practical with gigabit switches and merged cards, but you don't take a high security for paid pennies.

• Don't wink with cheap roses

  Another problem of self-made merzheviks is the filthy obscenity of cheap wall sockets. The stench leads to inconsistencies in the impedance, the results are blamed on the cost of return, and after them, the change in throughput capacity. Obviously, you can try to find out the reason “on the forehead”, but all the same, it’s better for you to get a mesh tester, which can reveal the cost of spending that crossover. Abo just put up with the low speed.

• Exchange according to the dozhina and topology

  1000BaseT is the maximum length of the segment, like 10/100BaseT. Thus, the maximum diameter of the fence is 200 meters (from one computer to another through one switch). As for the topology of 1000BaseT, then the same rules apply, that for 100BaseT, for the sake of admissibility, there is only one repetition per segment of the link (or, to be more precise, for one “duplex collation domain”). But gigabit ethernet shards don't support full duplex transmission, you can forget about the rest of it. Zagalom, as your network miraculously felt like 100BaseT, you are not guilty of problems when switching to gigabit.

Cable for gigabit Ethernet, prodovzhennya

For laying new tethers, the most beautiful vicorist cable CAT 5e. I want CAT 5 and CAT 5e offensive to skip the frequency of 100 MHz, CAT5e cable is provided additional parameters important for short transmission of high frequency signals.

Have a look at the following Belden documents for more information on CAT 5e cable specifications (English):

If you want a modern CAT 5 cable that will work wonderfully with 1000BaseT, it's better for you to choose CAT 5e if you want to guarantee a high bandwidth building. However, you may want to consider the versatility of a CAT 5 and CAT 5e cable and use your wallet.

The only thing you need to know about - recommendations for buying CAT 6 cable for gigabit Ethernet. CAT 6 letters updated to TIA-568 standard in red 2002і він pass frequencies up to 200 MHz. The sellers singsongly entice you to buy the most valuable category yourself, but you will need it, only if you plan to indulge merezhu 10 Gb/s Ethernet over medium wires, which is hardly real at the same time. What about CAT 7 cable? Forget about new!

If you have a good sum, then it’s better to spend on specialist-merezhnik, what a Volodya Sufficient proof of laying gigabit lines. Fahivets can competently lay cables or twist your іsnuyuchu merezha work with gigabit Ethernet. When installing a CAT 6 cable, we recommend that you turn for help to professionals, shards of this cable will wrap the radius of the bend and special roses.

Gigabit owned

Singing world food "gigabit chi nі" could be the subject of a super-cookie rіk chi kіlka rokіv that. As a matter of fact, the purchase of SOHO, moving from 10 to 10/100 Mbit / s, is already being marveled at a glance. Newer computers are equipped with 10/100 Ethernet ports, and routers now use 10/100 switches rather than 10BaseT hubs. However, such a change did not last long, but the favor of home merzheviks could not help. The stench is satisfied with the obvious possessions.

For the price, change us for a fee to corporate coristuvacha, as they buy today in mass amounts less than 10/100 of the possession, which allows you to lower it to a new price. As only a few chiropractors of a calm possession have shown that they can beat 10BaseT chips in 10/100 variants more expensive, They didn’t think about it for a long time.

In this way, yesterday's architecture based on 10BaseT concentrators invariably moved to today's 10/100 switching networks. Such a transition is known to me from 10/100 to 10/100/1000 Mb/s. І wanting to the turning point, I lost more rіk chi two, transition already swayed and the prices are steadily continuing the fall down.

All you need is to buy a small gigabit card and a gigabit switch. Let's take a look at a few reports.

• Merezhev cards

  Firm 32-bit PCI 10/100/1000BaseT mesh cards such as Intel PRO1000 MT, Netgear GA302T and SMC SMC9552TX cost $40 to $70 on the Internet. Products from other echelons are cheaper by about $5. If you want a gigabit mesh card about two and a half times more expensive than an average 10/100 cards, it’s unlikely that your hamanets will remember whether it’s retail, as you can’t buy them in wholesale lots.

  You can find some cards that support not only a 32-bit PCI bus, but also a 64-bit one, but cost the stench more expensively. Whatever you think, then CardBus adapters for your laptops. For some reason, virobniks are aware that laptops do not need gigabit storage.

• Commutators

  And the price axis 10/100/1000 switches will make you think ten times about the transition to gigabit Ethernet. The good news is that today gigabit commutators have already appeared, which can be cheaper for their cherished brothers for the corporate market.

  You can buy a simple 10/100/1000 10/100/1000 Netgear GS104 switch for less than $225. If you want to use your choice on smaller companies like TRENDnet TEG-S40TXE, change the price to $150. Few chotirioh ports - be kind. The eight-port version of the Netgear GS108 will set you back around $450, while the TRENDnet TEG-S80TXD is around $280.

  It's a shame that a five-port 10/100 switch today costs less than $20, the price per gigabit seems to be high. But guess what: recently, you could buy less than $100+ wired gigabit switches per port. Prices go straight for the right one!

Chi happen to change computers?

Let's see a small secret of gigabit Ethernet: under Win98 or 98SE you, better for everything, do not take away any advantage over gigabit speed. And if you want to help edit the registry, you can try to improve the throughput of the building, but all the same you don’t take away the real increase in productivity equal to the exact 10/100 possessions.

The problem lies in the TCP / IP Win98 stack, which is not the case for the expansion of high-level networks. The stack is blamed for problems navit from vikoristannyam 100BaseT Merezhi, what else can you say about a gigabyte call! Let’s turn to the other side of the food, but for now, you can’t look at it anymore Win2000і WinXP for robots with gigabit Ethernet.

The rest of the proposition is already n_yak not maybe on the grounds that only Windows 2000 and XP support gigabit cards. We simply did not overestimate the productivity under other operating systems, so please, be kind, respectful!

If you think about it, if you happen to find a good old computer and buy a new one for a gigabit Ethernet station, then our answer is “maybe”. Judging by our practical knowledge, one hertz of “current” processors is equal to one bit per second of bandwidth. One of the virobniks of a gigabit land-based possession has waited with us: be it a car clock frequency 700 MHz otherwise, it is not possible to win the bandwidth of a gigabit Ethernet building in the world. Also, to get the old gigabit Ethernet computers out of the correct operating system is all the same, a dead poultice. You better drink swidkosti 100-500 Mbps

Immediately go a lot of rozmos about those who have already massively switched to gigabit shvidkost when connected kіntsevyh koristuvachіv local merezh, as well as the food about the truthfulness and progressivity of the solution “fiber to the working place”, “fiber to the booth” is again broken down. At the link with this article, which will describe the standards not only on the mid-range, but first, on the GigE fiber-optic interface, it will be a whole day and its own.

Gigabit Ethernet architecture

Figure 1 shows the structure of the Gigabit Ethernet peers. Yak i in the standard fast ethernet, Gigabit Ethernet does not use a universal signal coding scheme, which would be ideal for all physical interfaces - so, on the one hand, for the 1000Base-LX / SX / CX standards, 8B / 10B coding is used, and on the other side, for the 1000Base-T there is a special extension of the TX/T2 line code. The function of coding depends on the level of coding of the PCS, located below the middle to the GMII interface.

Rice. 1. Structure equal to the Gigabit Ethernet standard, GII interface and Gigabit Ethernet transceiver

GMII interface. The middle independent interface GMII (Gigabit Media Independent Interface) ensures interoperability between MAC and physical levels. GMII interface for extended MII interface and can support speed 10, 100 and 1000 Mb/s. Vіn may be okremі 8 bіtnі priymаch i tranvach, і can pіdtrimuvati yak nіvіvduplexy, і duplex modes. Of course, the GMII interface carried one signal, which ensured synchronization (clock signal), and two signals became the line - the first one (at the ON station) indicates the presence of the carrier, and the other (at the ON station) to talk about the presence of collisions - and still a few others signal channels and food. The transverse module, which maintains the physical level and secures one of the physical media of the downstream interfaces, can be connected for example to a Gigabit Ethernet switch for an additional GMII interface.

Implementation of the physical coding of the PCS. When connected to 1000Base-X group interfaces, the PCS drive is powered by a 8B10B block overworld coding, aligned with the ANSI X3T11 Fiber Channel standard. Similar to the reviewed FDDI standard, only on the basis of a collapsible code table of skin 8 input bits, recognized for transmission to remote higher education institutions, are converted into 10 bit symbols (code groups). Krym tsgogo at the end of the last stream there are special control 10 bit symbols. The butt of the control characters can be symbols, changing the extension of the carrier (updating the Gigabit Ethernet frame to the minimum size of 512 bytes). When connected to a 1000Base-T interface, the PCS drive uses special coding, for safe transmission of UTP Cat.5 pairs over torsion up to 100 meters - TX / T2 line code, expanded by Level One Communications.

Two signals will become a line - a signal of the presence of a carrier and a signal of the presence of a collision - are generated by a sim alert.

Pіdrіvnі PMA and PMD. Physical Gigabit Ethernet fiber interfaces, including traditional twisted pair of category 5, as well as multi-mode and single-mode fiber. The PMA redirection converts the parallel flow of symbols from the PCS to the last flow, and also reverses the reversal (deparallelization) of the input sequential flow of the PMD. Drive PMD determines optical/electrical characteristics physical signals for different mediums. In general, there are 4 different types of physical interfaces of the medium, which are in the specification of the standard 802.3z (1000Base-X) and 802.3ab (1000Base-T), (Fig. 2).

Rice. 2. Physical interfaces to the Gigabit Ethernet standard

1000Base-X interface

The 1000Base-X interface is grounded to the Fiber Channel physical layer standards. Fiber Channel is a technology for interoperability between workstations, supercomputers, storage facilities and peripheral nodes. Fiber Channel can be 4-tier architecture. The bottom two layers FC-0 (Interface and Media) and FC-1 (Encode/Decode) are ported to Gigabit Ethernet. The legacy of Fiber Channel is a vaunted technology, such a transfer has greatly reduced the time for the development of the original Gigabit Ethernet standard.

The 8B/10B block code is similar to the 4B/5B code adopted by the FDDI standard. However, the 4B / 5B code is dropped from Fiber Channel, because this code does not provide a balance for fast strum. The balance can potentially be brought to the heating of laser diodes, which can lie in the transmitted data, the fragments of the transmitters can transmit more battles "1" (viprominuvannya є), lower "0" (viprominuvannya no), which can be the cause of additional pardons when high clothes transmission.

1000Base-X is subdivided into three physical interfaces, the main characteristics of which are listed below:

The 1000Base-SX interface defines the laser with an allowable delay in the range of 770-860 nm, the intensity of the transmission in the range of -10 to 0 dBm, with an ON / OFF (signal / signal) ratio of not less than 9 dB. Receiver sensitivity -17 dBm; 0 dBm pickup value;

The 1000Base-LX interface defines the laser with an allowable delay in the range of 1270-1355 nm, the intensity of the transmission in the range of -13.5 to -3 dBm, ON / OFF (signal / silent signal) not less than 9 dB. Receiver sensitivity -19 dBm, receiver intensity -3 dBm;

1000Base-CX screened twisted-pair (STP "twinax") on short spans.

For finalization, Table 1 lists the main characteristics of optical transceiver modules that are manufactured by Hewlett Packard for standard 1000Base-SX (model HFBR-5305 = 850 nm) and 1000Base-LX (model HFCT-5305 = 13) interfaces.

Table 1. Technical characteristics of Gigabit Ethernet optical receiver-transmitters

Standards for 1000Base-X standards, which are supported, are indicated in Table 2.

Table 2. Technical characteristics of Gigabit Ethernet optical receiver-transmitters

When coding 8B/10B, the bit rate of the optical line becomes 1250 bit/s. Tse means that the bandwidth of the cable can be allowed to pass 625 MHz. Table 3 2 shows that this criterion for rows 2-6 is victorious. Through great speed Gigabit Ethernet transmissions, but we will respect the next long segments. The popularity of single-mode fiber is insane. In this case, the characteristics of optical devices can be significantly greater. For example, the NBase company produces switches with Gigabit Ethernet ports, which can provide a distance of up to 40 km over single-mode fiber without relays (they use Vuzkospectral DFB lasers, which work on up to 1550 nm).

special features of the batomode fiber

The world has a majestic kіlkіst corporate funds on the basis of a multimodal fiber-optic cable, with fibers 62.5/125 and 50/125. Therefore, it is natural that at the stage of molding the Gigabit Ethernet standard, the task of adapting this technology for vikoristannya in the basic rich-modal cable systems. In the course of the investigation of the specifications of 1000Base-SX and 1000Base-LX, one more anomaly was detected, due to the variation of laser transmissions with a multimodal fiber.

Bagatomodov fiber was designed for sleeping victoria with light-emitting diodes (viprominence spectrum 30-50 ns). Incoherent vibrance of such light-emitting diodes is consumed by the fiber over the entire area of ​​the light-bearing core. As a result, impersonal mode groups are generated in the fiber. The signal that is being developed is well suited to the description of my intermodal dispersion. The efficiency of using such light diodes as transmitters in the Gigabit Ethernet standard is low, due to high frequency modulation - the speed of the bit stream in the optical line is 1250 Mbaud, and the speed of one pulse is 0.8 ns. The maximum speed, the number of light diodes for transmitting a signal of a multimodal fiber, becomes 622.08 Mbps (STM-4, with the enhancement of the overworld code 8B / 10B, the bit rate in the optical line is 777.6 Mbps). Therefore, Gigabit Ethernet has become the first standard that regulates the use of laser optical transmissions in combination with multimodal fiber. The area of ​​​​introduction of viprominuvannya at the fiber from the laser is significantly smaller, lower the size of the core of the high-mode fiber. Tsey fact by itself does not yet lead to a problem. At the same time, at technological process Variation of standard commercial high-mode fibers is allowed to reveal some non-critical defects in the traditional vicarious fiber (clearance at the margins of the permissible), the most significant near the axis of the core of the fiber. Although such a rich-mode fiber is more than satisfied with the standard, coherently light from the laser, introduced in the center of such a fiber, passing through the areas of inhomogeneity of the fracture indicator, then splitting on a small number of modes, then spreading along the fiber with different optical paths different swedishness. This phenomenon appears to be a differential modal dimming DMD. As a result, phase noise between modes appears, which leads to negligible interference on the receiving side and a significant increase in the number of pardons (Fig. 3a). Respect, that the effect is manifested only with a one-hour run of low reasons: less fiber in the distance, less laser transmitter in the distance (reasonably satisfied with the standard) and less distance introduction of the fiber. On the physical side, the effect of DMD is due to the fact that the energy from the coherent core is distributed in the middle of a small number of modes, even as the incoherent core causes the large number of modes to be step by step. The investigations show that the effect is stronger for different ranges of long-range lasers (with a transparency of 1300 nm).

Fig.3. Broadening of coherent vibration in multimode fiber: a) showing the effect of differential modal noise (DMD) with axial introduction of vibration; b) Non-axis introduction of coherent vibration in the bagatomode fiber.

An anomaly was assigned in the highest trend, which can lead to a change in the maximum length of the segment on the basis of a multimodal FOC. Oskіlki standard is responsible for ensuring a 100-hundred-hundred-thousand-thousandth robot guarantee, the maximum length of a segment may be regulated based on the possibility of manifesting the DMD effect.

1000Base-LX interface. In order to save more power and unique non-transmission of behavior to the Gigabit Ethernet channel through an anomaly, it is recommended to introduce a boost in the non-central part of the core of the high-mode fiber. Viaprominyuvannya through the aperture razbizhnosti vstigaє evenly rozpodіlititsya throughout the core of the fiber, strongly easing showing the effect, although the maximum length of the segment and after that is covered with fouling (Table 2). Specially designed transitional single-mode optical cables MCP (mode conditioning patch-cords), in which one of the cables (and the one that is planned to be accompanied by a multimode fiber) may have a small displacement in the axis of the core of the fiber. An optical cord, which can be one z'єdnuvach - Duplex SC with a sealed core, and the other one - a great Duplex SC, can be called like this: MCP Duplex SC - Duplex SC. It seems that such a cord is not suitable for traditional devices, for example, Fast Ethernet, through a large amount of money spent on a stick with MCP Duplex SC. Transitional MCP can be combined on the basis of single-mode and multi-mode fibers and a spacer element between fibers in the middle. Only a single-mode end of the line is connected to the laser transmission. As far as priymach, then a standard bagatomodovy successful cord can be connected to the new one. The switching of the transitional MCP cords allows the introduction of a rich mode fiber through an area offset by 10-15 µm from the axis (Fig. 3b). In this way, the possibility of using 1000Base-LX interface ports and single-mode fiber optic cables is saved;

1000Base-SX interface. Since the 1000Base-SX standardization interface is only for whiskers with a multi-modal fiber, a shift in the area of ​​​​introduction of vibration in the central axis of the fiber can be implemented in the middle of the extension itself, and they themselves take the need for a whisker of the optical cord.

1000Base-T interface

1000Base-T - the same standard Gigabit Ethernet interface for transmission over non-shielded torsion pairs of category 5 and more on distances up to 100 meters. For transmission, all pairs of pairs of a mid-wire cable are required, the speed of transmission over one pair is 250 Mbit / s. It is transmitted that the standard is secure duplex transmission, moreover, given the skin parity will be transmitted at the same time in two directions - dual duplex. 1000Base-T. It was difficult to technically implement duplex transmission of 1 Gb/s over UTP cat.5 torsion pairs, significantly lower than that of the 100Base-TX standard. Injection of near and far transitional transitions into three su- per twisted pairs per qiu pair in a choti-pair cable leads to the distribution of a special scrambled transitional transmission, and an intelligent node to recognize and recognize the signal at the receiver. Dekіlka methods of coding on the back were considered as candidates for validation in the 1000Base-T standard, among them: 5-level pulse-amplitude coding PAM-5; Quadrature amplitude modulation QAM-25, and below is a brief summary of the idea of ​​PAM-5, residually hardened as a standard.

Why 5-equal coding? Wider chotirirіvneve coding is done in pairs. The most common 4 different combinations - 00, 01, 10, 11. The transmitter can set the skin pair of bits to set its own voltage level of the transmitted signal, which will change the frequency of modulation of the choirir signal by 2 times, 125 MHz instead of 250 MHz), (Fig. 4) frequency of viprominuvannya. The fifth riven of contributions to the creation of the transcendental code. After that, it becomes possible to correct pardons at receptions. Tse gives an additional reserve of 6 dB for the signal-to-noise ratio.

Fig.4. Scheme of 4-layer coding PAM-4

rіven MAC

The MAC equivalent to the Gigabit Ethernet standard uses the same CSMA/CD transmission protocol as the ancestors of Ethernet and Fast Ethernet. The main exchanges for the maximum length of a segment (or a colloidal domain) are determined by this protocol.

The IEEE 802.3 Ethernet standard has a minimum frame size of 64 bytes. The very value of the minimum frame size determines the maximum distance between stations (collision domain diameter). The hour that the station transmits such a frame is the hour for the channel - 512 BT or 51.2 μs. The maximum length of the Ethernet link depends on the ability to resolve collisions, and the hour itself, for which signal to reach the remote node and turn back RDT cannot override 512 BT (without preamble adjustment).

When switching from Ethernet to Fast Ethernet, the speed of transmission is increased, and the hour of broadcasting a frame is 64 bytes, and it will be shortened - it is more expensive 512 BT or 5.12 µs (Fast Ethernet 1 BT = 0.01 µs). In order to be able to show all the collisions until the end of the transfer to the frame, as before, it is necessary to satisfy one mind:

Fast Ethernet lacked the same minimum frame size as Ethernet. This saved the confusion, but it led to a significant change in the diameter of the colloidal domain.

I know, however, through the advancement, the Gigabit Ethernet standard is guilty of introducing the minimum and maximum frame sizes, as adopted in Ethernet and Fast Ethernet. Ale, the speed of the transfer increases, depending on the hour of the transfer of the package of a similar time. For the sake of saving a lot of minimal time for the frame, it would have led to a change in the diameter of the frame, which did not exceed the bi-20 meters, which is a little short. To that, with the expansion of the Gigabit Ethernet standard, it was necessary to increase the channel's hour. For Gigabit Ethernet, it is necessary to set 4096 BT and for 8 times I switch the hour to the Ethernet channel and Fast Ethernet. Ale, in order to improve the complexity with Ethernet and Fast Ethernet standards, the minimum size of the frame was not increased, but an additional field was added to the frame, which took away the name "extension of the nose."

extension nose (carrier extension)

Symbols in the additional field do not carry service information, but they start the channel and increase the number of hours. As a result, the collision will be registered by all stations with a larger diameter of the collision domain.

If the station wants to transmit a short (less than 512 bytes) frame, the same field is added before transmission - extension of the carrier, which adds the frame to 512 bytes. The field of the control sum is calculated more than the original frame and is expanded by the fields of expansion. When a frame is received, the expansion field is displayed. Therefore, LLC navit does not know about the presence of the extension field. If the frame is expanded, or if it is transferred 512 bytes, the extension field is carried daily. In Fig. 5, the indications are the format of the Gigabit Ethernet frame for the hour of the change in the expansion of the nose.

Fig.5. Gigabit Ethernet frame from extension field.

Packet Bursting

Expanding the nose is the most natural solution, as it allowed to save the money with the Fast Ethernet standard, and this is the diameter of the colloidal domain. Ale, it called to a zayvoї vitrati smugi passing. Up to 448 bytes (512-64) can be idle during short frame transmission. At the stage of development of the Gigabit Ethernet standard, NBase Communications has introduced a proposal for the modernization of the standard. Tsya modernization, package revantage is named, allowing more effective victorious expansion. If the station/switch has a few small frames to edit, then the first frame is supplemented with a field of extension up to 512 bytes, and edited. Other frames are managed after a minimum inter-frame interval of 96 bits, with one important fault - the inter-frame interval is filled with extension symbols, (Fig. 6a). In this way, the middle is not locked between the parcels of short original shots, and be it any other attachment to the line, it cannot be wedged into the transmission. Таке пристроювання кадрів може відбуватися до тих пір, поки повна кількість переданих байт не перевищить 1518. Пакетна перевантаженість зменшувати ймовірність утворення колізій, оскільки перевантажений кадр може випробувати колізію тільки на етапі передачі першого свого оригінального кадру, включаючи розширення носія, що, безумовно, збільшує продуктивність measures, especially when great adventures(Fig.6-b).

Fig.6. Packet revantage: a) transfer of frames; b) transmission line behavior.

According to the materials of the company "Telecom Transport"

Virishit, chi is necessary to perfect your merezh.

• You, as well as members of your family, regularly capture large files, broadcast media on the Internet, or watch other tasks, as they greatly rob your media, for example, a server with file hosting, or online games, we were more than satisfied with the upgrade to Gigabit Ethernet.
• It is necessary for the middle and great enterprises, so that a lot of coristuvachiv would be brought together through the line and could increase their productivity at once.
• Private individuals, like vikoristovuyut the Internet one by one for non-resource-rich fencing plants, like e-mail, mittevi podomlennya Or web surfing may not benefit from reduced network access to Gigabit Ethernet.