Fast Ethernet technology. Fast Ethernet technology, special features, physical level, rules to change the types of frames that are selected in the LOM Token Ring
Testing laboratory "ComputerPress" carried out testing of applications for 10/100 Mbit/s interfacing cards to the Fast Ethernet standard for the PCI bus in workstations. We chose the widest cards in the given hour with a bandwidth of 10/100 Mb/s, shards, first, stinks can win in Ethernet, Fast Ethernet and other networks, and, in another way, promising Gigabit Ethernet technology (capacity building up to 1000 Mbit / s) is still zastosovuetsya most of all for the connection of hard servers to the network core of the network. Superimportantly important are those, which are passively owned by the fence (cables, sockets, thinly) are victorious in the fence. Well, as for the Ethernet network, a cable for torsion pairs of category 3 is sufficient, but for Fast Ethernet, category 5 is required. Rozsіyuvannya signal, filthy protection from noise can significantly reduce the throughput of the buildings of the city.
The method of testing was assigned to us in front of the index of effective productivity (Performance/Efficiency Index Ratio - nadal P / E-index), and only then - the absolute value of throughput. The P/E-index is calculated as a ratio of the throughput capacity of the tethered card in Mbit/s up to the degree of CPU utilization in HDCs. This index is the Galuzev standard for determining the productivity of treadmill adapters. Vіn buv introductions for vrahuvannya vekoristannya by the resource maps of the central processor. On the right, in the fact that some of the merging adapters are used to achieve maximum productivity by using the way of merging for the merging operations of a large number of cycles of the computer's processor. The minimum processor load and the remarkably high throughput can be of great importance for the development of the critically important business of multimedia applications, as well as real-time tasks.
Were protested cards, as they are most often won for work stations at corporate and local networks:
- D-Link DFE-538TX
- SMC EtherPower II 10/100 9432TX/MP
- 3Com Fast EtherLink XL 3C905B-TX-NM
- Compex RL 100ATX
- Intel EtherExpress PRO/100+ Management
- CNet PRO-120
- NetGear FA 310TX
- Allied Telesyn AT 2500TX
- Surecom EP-320X-R
The main characteristics of the mesh adapters that are tested are shown in Table. 1 . Let's explain the deakі terms, like in the tables. Automatically setting the speed of the connection means that the adapter itself sets the maximum possible speed of operation. In addition, at the time of automatic change of speed, there is no additional adjustment when switching from Ethernet to Fast Ethernet and back is not required. Therefore, as a system administrator, it is not necessary to reconfigure the adapter and reconfigure the drivers.
Support for the Bus Master mode allows you to transfer data without intermediary between the memory card and computer memory. Tim himself bulo the central processor will vibrate until the end of other operations. Tsya vlastivist became the de facto standard. It is not for nothing that all other cards support the Bus Master mode.
Remote Awareness (Wake on LAN) allows you to wake up your PC as needed. This is due to the ability to service the computer during non-working hours. For this purpose, there are three-contact roses on the system board and to the adapter, which are connected with a special cable (included before the delivery kit). In addition, you need special keruyuche software security. Wake on LAN technology has been expanded by the Intel-IBM alliance.
Full-duplex mode allows you to transmit data at the same time in both directions, full-duplex - only in one. Thus, the maximum possible throughput for the full-duplex mode is 200 Mb/s.
The DMI interface (Desktop Management Interface) gives you the ability to capture information about the configuration and resources of the PC for additional management software.
WfM (Wired for Management) specification support ensures the interoperability of the wire adapter with wire management software and administration.
For a distant zavantazhennya OS computer'yut at least a few adapters mayut special memory BootROM. This allows you to effectively hack a number of diskless workstations. Most of the tested cards had only a socket for installing BootROM; the BootROM chip itself sounds like an option, which can be fixed.
The ACPI (Advanced Configuration Power Interface) subtrip allows you to change the power supply. ACPI is a price new technology that ensures the operation of the life care system. Vaughn runs on victorious both hardware and software tools. Basically, Wake on LAN is warehouse ACPI.
The firm's ability to increase productivity allows to increase the efficiency of the work of the merging card. The most prominent of them are Parallel Tasking II by 3Com and Adaptive Technology by Intel. Qi cats sound buvayut patented.
Support for the main operating systems is provided by almost all adapters. To the main operating systems lie: Windows, Windows NT, NetWare, Linux, SCO UNIX, LAN Manager and others.
The service level of support is evaluated by the availability of documentation, floppy disks with drivers and the possibility of obtaining the remaining versions of drivers from the company's website. I will not leave the role played by the packaging. From the point of view, the best, in our opinion, are the least adapters of D-Link, Allied Telesyn and Surecom. Ale zagalom, the rіven pіdtrimka appeared for all cards of the past.
Call the warranty extended for the entire hour of operation of the tether adapter (additional warranty). Sometimes they are intermingled with 1-3 fates.
Testing technique
In all tests, the remaining versions of the drivers for the integrated cards were defeated, as they were taken from the Internet servers of the respective drivers. In case, if the driver of the merging card allowed for some tweaking of that optimization, the settings behind the locking (crim of the Intel merging adapter) were overridden. Significantly, 3Com and Intel cards are equipped with the richest additional capabilities and functions.
The productivity boost came from the help of Novell's Perform3 utility. The principle of this utility lies in the fact that a file of small size is copied from the working station to the server's partition disk, which is divided, after which the VIN is left at the server's file cache and after a specified time interval, the sound is read. Tse allows you to reach the type of memory-merezha and put in the gaps associated with disk operations. The parameters of the utility include the initial expansion of the file, the final expansion of the file, and the short change of the expansion and the hour of the test. The Novell Perform3 utility displays productivity values for files of various sizes, average and maximum productivity (KB/s). To customize the utility, the following parameters were set:
- Cob rozmir file - 4095 bytes
- Final size of the file - 65 535 bytes
- Croc file extension - 8192 bytes
The hour of testing with the skin file was set to 20 seconds.
In the skin experiment, a pair of the same lace cards was tested, one of which was processed on the server, and the other - on the working station. It turns out that we are expanding our practice, the shards at the servers start to sound like specialized mesh adapters, ensuring the assignment of additional functions. And just like that - one and the same cards are installed on the server, and on the working stations - testing is carried out by all test laboratories in the world (KeyLabs, Tolly Group, etc.). The results seem to be somewhat lower, but the experiment seems to be clean, the shards on all computers are less likely to analyze the mesh maps.
Compaq DeskPro EN client configuration:
- processor Pentium II 450 MHz
- 512 KB cache
- RAM 128 MB
- hard drive 10 GB
- OS Windows NT Server 4.0 c 6 a SP
- TCP/IP protocol.
Compaq DeskPro EP server configuration:
- Celeron 400 MHz processor
- RAM 64 MB
- hard drive 4.3 GB
- operating system Microsoft Windows NT Workstation 4.0 c c 6 a SP
- TCP/IP protocol.
Testing was carried out in the brain, if the computers were connected with a UTP Category 5 crossover cable. For an hour of testing, the cards were tested in 100Base-TX Full Duplex mode. In this regime, the throughput of buildings is seen as a thing for the account of the fact that part of the service information (for example, confirmation to the receptionist) is transmitted at the same time with the basic information, which is assessed. At the minds, it was possible to fix the high value of the throughput building; for example, for the 3Com Fast EtherLink XL 3C905B-TX-NM adapter, the average is 79.23 Mbps.
Processor efficiency was monitored on the server for the additional Windows NT Performance Monitor utility; data was written to a log file. The Perform3 utility was run on the client, so as not to interfere with the server processor's involvement. As the processor of the server computer was beaten by Intel Celeron, the productivity of such a processor is much lower than the productivity of Pentium II and III processors. Intel Celeron wins over: on the right, in the fact that the fragments of the processor's vanity are shown to have a great absolute error, in times of great absolute values, the significant error is less.
After a skin test, the Perform3 utility places the results of its work in a text file that looks like a set of data in an offensive form:
65535 bytes. 10491.49 KBps. 10491.49 Aggregate KBps. 57343 bytes. 10844.03 KBps. 10844.03 Aggregate KBps. 49151 bytes. 10737.95 KBps. 10737.95 Aggregate KBps. 40959 bytes. 10603.04 KBps. 10603.04 Aggregate KBps. 32767 bytes. 10497.73 KBps. 10497.73 Aggregate KBps. 24575 bytes. 10220.29 KBps. 10220.29 Aggregate KBps. 16383 bytes. 9573.00 KBps. 9573.00 Aggregate KBps. 8191 bytes. 8195.50 KBps. 8195.50 Aggregate KBps. 10844.03 Maximum KBps. 10145.38 Average KBp.
Display file size, average throughput for the selected client and all clients (only one client per client), and display the maximum and average throughput for the entire test. The subtraction of the average values according to the skin test was shifted from Kb / s Mb / s according to the formula:
(KB x 8)/1024,
That value of the P/E index was calculated as a ratio of the throughput to the processor utilization in hundreds of cells. The average value of the P/E index was calculated based on the results of three surveys.
Somehow Perform3 utility on Windows NT Workstation had the following problem: when writing a file to a smaller disk, the file is also written to the local file cache, the sounds are read easily every year. The results were hostile, if not unrealistic, and there were no transfers of data as such. In order for the programs to be able to take the lesser disks, which are divided, as the primary local disks, in the operating system, there is a special lesser component - the redirector, which redirects the input-viewing requests to the lesser. The best minds of the robot in the process of writing a file to a partitioned disk, which is divided, redirector uses the Windows NT cache algorithm. Also, when writing to the server, a record is made in the local file cache of the client machine. And for the testing to be carried out, it is necessary that the cache was carried out only on the server. In order to avoid caching on the computer-client, the Windows NT registry had a parameter value changed, which allowed the caching to be disabled, as if the redirector was disabled. Axis yak tse bulo zrobleno:
- Way at the Registry:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Rdr\Parameters
Parameter name:
UseWriteBehind allows write-behind optimization for writing files
Type: REG_DWORD
Value: 0 (per lock: 1)
- Way at the Registry:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Lanmanworkstation\parameters
Parameter name:
UtilizeNTCaching specifies whether the redirector will override the Windows NT cache manager to cache files instead.
Type: REG_DWORD Value: 0 (per lock: 1)
Merezhevy Intel EtherExpress PRO/100+Management adapter
The bandwidth of the cards and the frequency of the CPU turned out to be practically the same as those of 3Com. Shown below is a picture of how to fix the map.
The new Intel 82559 controller, installed on this card, ensures high performance, especially in Fast Ethernet networks.
The technology that Intel has won in its Intel EtherExpress PRO/100+ card is called Adaptive Technology. The essence of the method is in the automatic change of hourly intervals between Ethernet packets depending on the cost of the measure. With an increase in the number of vanishings, between the same Ethernet packets dynamically increase, which allows you to change the number of calls and increase the throughput of the building. With a small amount of interest, if the number of calls is small, the time intervals between the packages are reduced, which also leads to an increase in productivity. The world's greatest success of this method is due to large Ethernet segments, then in quiet places, if in the topology of a network hubs, and not switches, prevail.
The new Intel technology, called Priority Packet, allows you to regulate traffic that passes through the border card, up to the priorities of four packets. Tse gives the opportunity to improve the speed of transmission for critically important additions.
Support for virtual local VLAN merging (IEEE 802.1Q standard).
There are only two indicators on the board - robot / day, speed 100.
www.intel.com
SMC EtherPower II 10/100 SMC9432TX/MP Intermediate Adapter
In the architecture of the map, there are two promising technologies SMC SimulTasking and Programmable InterPacket Gap. The first technology predicts 3Com Parallel Tasking technology. Having given the results of testing for the cards of these two types, you can generate notes about the effectiveness of the implementation of these technologies. It is also significant that this mesh card showed the third result in terms of productivity and P / E index, outperforming all cards, cream 3Com and Intel.
There are several light indicators on the card: speed 100, transfer, call, duplex.
Addresses of the main Web site of the company: www.smc.com
Ethernet is the most widely used local network standard today. Zagalna kіlkіst merezha, yakі at once vicorist
fast ethernet
Fast Ethernet technology is richer than traditional Ethernet technology, but it is 10 times better for it. Fast Ethernet or 100BASE-T runs at 100 megabits per second (Mbps) instead of 10 for traditional Ethernet. 100BASE-T technology will use the same frame format as Ethernet and will not require changes to other protocols, additions to other operating systems at work stations. You can route and switch packets between 10 Mbps and 100 Mbps without broadcasting protocols and causing delays. Fast Ethernet technology uses CSMA/CD protocol to drive MAC for secure access to the transmission medium. The greater number of current Ethernet links is caused by the improvement of the "star" topology, the hub is the center of the wire, and the cables from the hub are connected to the skin computer. The same topology prevails in Fast Ethernet links, although the diameter of the link is sometimes smaller due to the higher speed. Fast Ethernet twisted-pair (UTP) twisted-pair twisted-pair cable (UTP) as specified by the IEEE 802.3u specification for 100BASE-T. The standard recommends twisting a cable of category 5 from two or two pairs of conductors, placed near a plastic sheath. Category 5 cables certified for 100 MHz bandwidth. 100BASE-TX has one pair of data transmissions, the other pair - signaling to the receiver.
The Fast Ethernet standard has three modifications for working with different types of cables: 100Base TX, 100Base T4 and 100Base FX. Modifications of 100Base TX and 100Base T4 are for a twisted pair, and 100Base FX are for an optical cable.
The 100Base TX standard allows for the inclusion of two shielded or non-shielded twisted pairs. One pair to serve as transmission, otherwise to the receiver. They can be supported by two main cable standards: Category 5 pair (UTP-5) is twisted to an unscreened pair and IBM Type 1 pair is twisted to a screened cable.
The 100Base T4 standard may have less interconnection to the cable, so that in the new task all pairs of an eight-wire cable are used: one pair for transmission, another for reception, and two pairs, which are lost, are used both for transmission and for reception. As a result, in the 100Base T4 standard, the reception and transmission of data can be carried out in three pairs. For the implementation of the 100Base T4 network, cables with unshielded twisted pair of category 3-5 and shielded type 1 are used.
The decline of Fast Ethernet and Ethernet technologies makes it easy to develop recommendations for congestion: Fast Ethernet is still quite stagnant in these organizations, as the classic Ethernet was widely victorious, but today it will require more bandwidth. In this case, the entire accumulation is taken from the work of the Ethernet and often the merezhna infrastructure.
For classic Ethernet, an hour of listening to a cell is set to the maximum time, as a 512-bit frame can pass as much as an hour, which is equal to the hour of processing that frame at a work station. For an Ethernet network, the distance is 2500 meters. Fast Ethernet has the same 512-bit frame per hour, which is required for processing at a work station, passing a total of 250 meters.
The main scope of work Fast Ethernet today - cemerezhі working groups and vіddіlіv. Dotsilno zdіysnyuvati transition to Fast Ethernet step by step, leaving Ethernet there, de good coping with the set tasks. One of the obvious options, if Ethernet is not going to be replaced by Fast Ethernet technology, is to connect to a number of old personal computers with the ISA bus.
Gigabit Ethernet/
The same technology wins the same frame format, the same method of access to the CSMA/CD transmission medium, the same flow control mechanisms and the same objects that manage, but Gigabit Ethernet is more similar to Fast Ethernet, more to Fast Ethernet or Ethernet . So, although Ethernet was characterized by the diversity of transmission mediums, which gave reason to talk about those who can work on a barbed dart, then in Gigabit Ethernet fiber optic cables become the dominant transmission medium (it is, obviously, far from far away). Ale z reshtoyu mi reportniche cognizable below). In addition, Gigabit Ethernet to put inconspicuously foldable technical tasks and visually rich things to the level of wiring. In other words, vin richly less universal, lower yogo fronts.
GIGABIT ETHERNET STANDARDS
The Main Usilla of the IEEE 802.3z Workgroup Directing the Designation of Physical Standards for Gigabit Ethernet. She took the ANSI X3T11 Fiber Channel standard as a basis, more precisely, two lower drivers: FC-0 (interface and transmission medium) and FC-1 (encoding and decoding). The fallow type of the physical medium, the specification of Fiber Channel is set at a given hour with a speed of 1062 gigabytes per second. Gigabit Ethernet has reduced the won to 1.25 gigabytes per second. With the coding for the 8B / 10B scheme, we require a transmission speed of 1 Gb / s.
Technologyethernet
Ethernet is the most widely used local network standard today.
Ethernet is the first standard for the experimental Ethernet Network, which Xerox developed and implemented in 1975.
In 1980, a number of companies DEC, Intel and Xerox jointly developed and published the Ethernet version II standard for a network based on coaxial cable, which became the remaining version of the Ethernet proprietary standard. This proprietary version of the Ethernet standard is called the Ethernet DIX or Ethernet II standard, based on the extensions of the IEEE 802.3 standard.
On the basis of the Ethernet standard, additional standards were adopted: in 1995 Fast Ethernet (addition to IEEE 802.3), in 1998 Gigabit Ethernet (divided IEEE 802.3z of the main document), which is rich in what is not independent standards.
For the transfer of dual information over the cable to all variants of the physical level of Ethernet technology, which ensures a throughput of 10 Mbit / s, the Manchester code is won (Fig. 3.9).
The Manchester code for coding one and zero has a potential difference, which is the front of the impulse. With the Manchester coding of the skin, the beat is subdivided into parts. The information is encoded by potential drops, which are found in the middle of the skin tact. One is encoded by a drop from a low signal level to a high one (by the leading edge of the pulse), and zero is by a reverse edge (by the trailing edge).
Rice. 3.9. Differential Manchester coding
The Ethernet standard (Fast Ethernet and Gigabit Ethernet) also uses the same method of data transmission medium - the CSMA / CD method.
The skin of the PC is used in Ethernet, based on the principle “Listen to the transmission channel, before that, send an announcement; listen, if you correct; pin the robot at a different code and try again.”
This principle can be deciphered (explained) as follows:
1. No one is allowed to overdo it at that hour, if there are other things to do (listen before him, how to correct).
2. As if two or more clerks begin to wake up at about the same moment, sooner or later they will "shine" one by one at the channel, which is called a collie.
Kolіzії it is not important to recognize, the stink shards call out a signal to cross, which is similar to the admissible warning. Ethernet can recognize the changeover and change the address of the right to start the transmission and the next hour, first of all, re-send the notification.
Reasons for the wide popularity of Ethernet (goodness):
1. Cheapness.
2. Great honor of victory.
3. Innovations that are being continued.
4. Wealth of choice of settling. There are a lot of people who want to try out the equipment and motivate merezh, which is based on Ethernet.
Shortcomings of Ethernet:
1. Mozhlivist zіtknen povіdomlen (kolіzії, reshuffle).
2. At the time of the great adventurousness, the hour of transmission is to reconcile non-transfers.
TechnologyTokenring
Token Ring ties, like Ethernet ties, characterize the medium of data transmission, which is divided, as if stacked over a cable, which connects all the stations of the tie in the ring. The circle is considered as a vital resource, which is being divided, and for access to the new one, it is not a vipadkovy algorithm that is needed, like in Ethernet networks, but determinations, foundations for transferring the rights to the stations of the circle in the first order. This right is transferred for an additional frame of a special format, which is called a marker, or a token.
Token Ring technology was developed by IBM in 1984, and then transferred as a draft standard to the IEEE 802 committee, which adopted the 802.5 standard in 1985.
The skin of the PC is practiced in Token Ring according to the principle “Check for the marker, as it is necessary to send a reminder, come to the marker, if you pass the check. To pass the marker, take a new reminder and send the marker away.
Merezhі Token Ring is processed from two bits by bits - 4 and 16 Mbit / s. The change of stations, which work on different shifts, is not allowed in the same quarter.
Token Ring technology is a folding technology, lower Ethernet. Vaughn may be the power of the spirit. At the Token Ring measure, the procedure for controlling the work of the measure is assigned, like a twisted link of a ring-like structure - the overlay frame must be rotated to the station-manager.
Rice. 3.10. Technology Principle TOKEN RING
In some cases, pardons have been detected in robots and merezhi are used automatically, for example, a marker can be reintroduced. In other cases, pardons are only fixed, and they are dismissed manually by the attendants.
To control the measure, one of the stations plays the role of the so-called active monitor. The active monitor is selected every hour to initialize the station as the station with the maximum MAC address. When the active monitor goes out of tune, the call initialization procedure is repeated and a new active monitor is selected. The Token Ring network can accommodate up to 260 knots.
The Token Ring hub can be either active or passive. The passive concentrator simply plugs in with internal links so that the stations that connect to these ports have made a ring. No signal strength, no resynchronization of passive MSAU is disabled.
An active hub defeats the function of signal regeneration, which is sometimes called repeating, like the Ethernet standard.
Token Ring can be combined with a mirror-kilts configuration. Terminal nodes are connected to MSAU for the topology of the star, and MSAU itself is connected through special ports Ring In (RI) and Ring Out (RO) to establish the main physical ring.
All stations at the kіltsі owen pratsyuvati on one shvidkostі or 4 Mbit / s or 16 Mbit / s. The cables that connect the station with the concentrator are called lobe cables, and the cables that connect the concentrators are called trunk cables.
The Token Ring technology allows for the connection of end stations and concentrators of various cable types:
– STP Type 1 – shielded twisted pair (Shielded Twistedpair).
It is allowed to connect up to 260 stations near the ring with a maximum of 100 meters of wiring cables;
- UTP Tour 3, UTP Tour 6 - Unshielded Twistedpair. The maximum number of stations is up to 72 for the length of the wiring cables up to 45 meters;
– fiber optic cable.
The distance between passive MSAUs can reach 100 m with STP Type 1 vicarious cable and 45 m with UTP Type 3 vicarious cable.
The maximum length of the Token Ring circuit should be 4000 m. Here qі obmezhennya is more important than po'yazanі z hourly turnover of the marker on kіltsyu.
You can adjust the timeout values for merging adapters in Token Ring merging nodes, so you can induce Token Ring merging with a large number of stations and with a large number of stations.
Advantages of Token Ring technology:
· Guaranteed delivery povіdomlen;
· High data transmission speed (up to 160% Ethernet).
Shortcomings of Token Ring technology:
· Necessary roads for access to the middle;
· The technology is more foldable in implementation;
· Required 2 cables (for transfer of power): one input, the other output from the computer to the hub;
· High versatility (160-200% of Ethernet).
TechnologyFDDI
FDDI (Fiber Distributed Data Interface) technology - fiber optic data distribution interface - is the first technology of local networks, in which the transmission medium has a fiber optic cable. Vinyl technology in the mid-80s.
FDDI technology is rich in why it is based on Token Ring technology, supporting the access method by passing the token.
The FDDI network will be based on two fiber-optic links, which will establish the main and backup routes for data transmission between the nodes of the network. The presence of two camps is the main way to increase sustainability to the FDDI borders, and the universities, if they want to accelerate with the promotion of the potential of reliability, are to blame and connect to both clusters.
In the normal mode, the data is allowed to pass through the nodes and all the substation to the cable only of the primary (Primary) ring, the whole mode of names by the Thru mode is "open", or "transit". The second ring (Secondary) does not win in this mode.
In time, be of any mind, if a part of the primary ring cannot transmit data (for example, by shaving the cable or the top knot), the primary ring unites with the second one, making a new single ring. This mode of robotic mesh is called Wrap, tobto gortannya or gortannya kіlets. Swallowing operation is controlled by concentrators and/or FDDI adapters.
Rice. 3.11. ITT with two cyclic cycles in emergency mode
To simplify the procedure, the data on the primary ring are always transmitted in one direction (on the diagrams, which are directly shown against the year's arrow), and on the secondary - at the back (shown behind the year's arrow). Therefore, with the establishment of a closed circle of two stations, the transmitting stations, like before, are connected to the receivers of the land stations, which allows the correct transmission and reception of information by the land stations.
Merezha FDDI can again reaffirm its practice in several different types of elements. When there are many merezhas, they break up into sprats that do not tie merezhas.
Rings in FDDI networks are considered as an important medium for data transfer, which is divided, and a special access method is assigned to it. This method is close to the Token Ring access method and is called the token ring method.
Inspection of the access method in that the hour of token deletion in the FDDI measure has ceased to be a constant value. This time to lie down in the face of the zavantage of the ring - with a small zavantazhennya, it will increase, and with great zavantazhennya, it can change to zero. Changes in the access method cost more than asynchronous traffic, which is not critical to a small delay in the transmission of frames. For synchronous traffic, the marker's hour, like before, is filled with a fixed value.
FDDI technology currently supports the type of cables:
– fiber optic cable;
– unscreened twisted pair of category 5. The remaining standard appeared later than the optical one and was called TP-PMD (Physical Media Dependent).
Fiber optic technology ensures the necessary data transmission from one station to another via optical fiber and designates:
Vikoristannya as the main physical core of the bugatomode fiber-optic cable 62.5 / 125 microns;
Vymogy to the tightness of the optical signals and the maximum extinction between the knots of the mesh. For a standard multi-mode cable, it can be brought up to a boundary distance between nodes of 2 km, and for a single-mode cable, it can be increased to 10–40 km, depending on the quality of the cable;
Wimogi to optical bypass switches and optical bypass switches;
Parameters of optical sockets MIC (Media Interface Connector), їх marking;
Vikoristannya for the transmission of light with a long wind 1.3 nm;
The maximum distance of the FDDI circuit should be 100 kilometers, the maximum number of stations with sub-connections at the circuit is 500.
The FDDI technology was developed for stowing at large yards, on the main lines between large yards, for example, yards, and also for connecting high-performance servers to the yard. Therefore, smuts are strong at retailers boules ( advances):
- high security of data transmission,
- compliance with the protocol;
- great number of connected stations between the hubs of the city.
All the goals were within reach. As a result, FDDI technology turned out to be more expensive, if not expensive. short). The emergence of a cheaper option for twisted betting has not cheaply reduced the connection rate of one university to FDDI. Practice has shown that the main area of application of FDDI technology has become the highways, which are formed from many lives, as well as the scale of the great city, tobto the MAN class.
TechnologyFastethernet
Use high-speed and low-cost technology to connect to a number of hard workstations led to the beginning of the 90s before the creation of an initiative group, as it was engaged in the quests of a new Ethernet, such a simple and effective technology
Fahivtsі split into two camps, which led to the appearance of two standards adopted in the autumn of 1995: the 802.3 committee approved the Fast Ethernet standard, which may repeat the Ethernet technology of 10 Mbit / s.
The Fast Ethernet technology saved the CSMA/CD access method from the shortcomings, depriving it of the same algorithm and the same clock parameters in bit intervals (the bit interval itself has changed tenfold). The characteristics of Fast Ethernet and Ethernet are physically displayed.
The Fast Ethernet standard has three physical level specifications:
- 100Base-TX for 2 pairs of UTP category 5 or 2 pairs of STP Type 1 (4V/5V encoding method);
- l00Base-FX for multimode fiber optic cable with two optical fibers (4V/5V coding method);
- 100Base-T4, which is used on 4 pairs of UTP category 3, but only three bets per hour for transmission, and reshto - for the detection of collisions (coding method 8B / 6T).
l00Base-TX/FX standards can be used for full duplex mode.
The maximum diameter of the Fast Ethernet line is approximately 200 m, and the exact value depends on the specifics of the physical medium. For Fast Ethernet domains, no more than one class I repeater is allowed (which allows translating code 4V/5V code 8V/6T and back) and no more than two repeaters class II (which does not allow translating code translation).
Fast Ethernet technology when working on a torsion pair allows two ports to choose the most efficient mode of operation - speed 10 Mb/s or 100 Mb/s, as well as full duplex or full duplex mode.
Technology Gigabit Ethernet
Gigabit Ethernet technology adds a new, 1000 Mb/s, step in the Ethernet family of services. This step allows you to efficiently build large local networks, for which servers and backbones of the lower levels operate at a speed of 100 Mbps, and the Gigabit Ethernet backbone combines them, ensuring a small amount of bandwidth.
Gigabit Ethernet technology retailers saved the great world of advancement with Ethernet and Fast Ethernet technologies. Gigabit Ethernet uses the same frame formats as the older versions of Ethernet, running in full-duplex and full-duplex modes, supporting the same CSMA/CD access method on the media with minimal changes.
To ensure an acceptable maximum frame diameter of 200 m in full duplex mode, the technology retailers went to increase the minimum frame size 8 times (from 64 to 512 bytes). It is also allowed to transmit a few frames later, without changing the middle at an interval of 8096 bytes, but the frames are not obligatory to add up to 512 bytes. Other parameters of the access method and the maximum frame size were left unchanged.
In 1998, the 802.3z standard was adopted, which designates the choice as a physical medium for three types of cable:
- bagatomode fiber optic (up to 500 m),
- single-mode fiber optic (up to 5000 m),
- sub-wire coaxial (twinax), for which data is transmitted at the same time by two medium shielded conductors on a distance of up to 25 m.
For the expansion of the Gigabit Ethernet option on UTP category 5, a special group 802.3ab was created, as it had already developed a draft standard for working on 4 UTP category 5 pairs.
Ease of installation.
Dobre vіdoma and the most expanded merezhev technology.
Not high variety of lace cards.
Possibility of implementation of various types of cable and schemes for laying the cable system.
Shortcomings of Ethernet
Reducing the real speed of transmission in a heavily entangled line, to a complete tooth, through conflicts in the middle of the transmission.
Troubleshooting for faults: when shaving the cable, it is necessary to remove the entire segment of the LOM, and it is difficult to locate the faulty vuzol and the yard.
Brief description of Fast Ethernet.
fast ethernet (Swedish Ethernet) - high-width technology, proponated by 3Com to implement Ethernet networks with 100 Mbps data transmission speed, which preserves the maximum features of 10-megabit Ethernet (Ethernet-10) and is implemented at the standard 802.3u (exactly up to 802.3u look at the divisions from 21 to 30). The access method is the same as that of the Ethernet-10 - CSMA/CD of the MAC level, which allows you to override the amount of software security and the ability to manage Ethernet networks.
Usі v_dminnostі Fast Ethernet vіd Ethernet-10 zseredzhenі physically. There are 3 options for cable systems:
rich-mode WOK (2 fibers are vicorous);
Merezhі structure- ієrarchіchna tree-like, pobudovan on hubs (like 10Base-T and 10Base-F), coaxial cable does not vibrate.
Merezha diameter Fast Ethernet is shortened to 200 meters, which is explained by the change in the hour of transmission of the frame, the minimum time is ten times for the increase in transmission speed ten times in pairs with Ethernet-10. Tim is no less, it is possible to create large networks based on Fast Ethernet technology, to a wide range of inexpensive high-speed technologies, as well as to the turbulent development of LOM based on commutators. With different switches, the Fast Ethernet protocol can be used in full-duplex mode, in which there is no border for a long distance, and there are no more borders for a long distance of physical segments, which can connect the auxiliary devices (adapter - switch or switch - switch).
The IEEE 802.3u standard defines three specifications of the Fast Ethernet physical layer, one by one:
100Base-TX - transfer of data for two non-canceled pairs of category 5 (2 pairs of UTP category 5 or STP Type 1);
100Base-T4- transfer of data for a few unopened pairs of categories 3, 4, 5 (4 bets UTP category 3, 4 or 5);
100Base-FX- transmission of data from two fibers of a bagatomode fiber.
Why is the hour of transmission of the frame of the minimum (maximum) time (at once from the preamble) at bit intervals for Ethernet 10Mb/s?
? 84 / 1538
What is PDV (PVV)?
PDV - hour, for which signal the colony will expand to the next node of the line - hour of moving turnover (Path Delay Value)
PVV - Path Variability Value
Why one exchange per PDV (PVV)?
PDV - no more than 575 bit intervals
PVV-when passing the sequence of frames through all repetitions, no more than 49 bit intervals
How many bit intervals to create a sufficient reserve of reliability for PDV? 4
If it is necessary to insure the maximum number of repetitions and the maximum amount of money? Why can't you just stop the rules "5-4-3" or "4 habiv"?
If different types of media transmission
Pererahuyte main mind and correct robotic Ethernet network, which is composed of segments in different physical nature.
at stations no more than 1024
dozhini all vіdgaluzhen no more than the standard
PDV no more than 575
PVV-when passing the sequence of frames through all repetitions, no more than 49 bit intervals
What should be done to understand the base of the segment for the hour of the PDV survey?
Tricks to be made by repeaters
Where does the sharpest point of view need to be clogged with personnel: in the right, left, and middle segments?
At the right - receiving
Which type of person needs to get PDV girls? Why?
Yakshcho rіzna dovzhina segmentіv іn the far edges of the merezі, tk. stinks may vary in the magnitude of the base zatrimka.
Brief description of the LOM Token Ring.
token ring (Markerne kіltse) - merezhna technology, in any station they can transmit data only to those, if the stink is carried by a marker that circulates without interruption around the kiltsyu.
The maximum number of stations in one station is 256.
The maximum distance between stations to deposit according to the type of medium (line connection) and storage:
Up to 8 kilometers (MSAU) can be connected by bridges.
Max.
Purpose of Token Ring.
Token Ring was proponated by IBM in 1985 (the first version appeared in 1980). The appointment of Token Ring was common among all types of EOMs that are issued by the company (from PCs to great EOMs).
What is the international standard for Token Ring technology?
Token Ring is the international standard IEEE 802.5.
How are the building passes secured by LOM Token Ring?
There are two variants of technology, which ensure the security of data transfer 4 and 16 Mb/s is available.
What is MSAU Multiple Access Attachment?
MSAU concentrator with stand-alone unit with 8 sockets for connecting computers for additional adapter cables and two end sockets for connecting to other concentrators for additional main cables.
Dekіlka MSAU can be constructively combined into a group (cluster / cluster), in the middle of which subscribers are connected in the ring, which allows to increase the number of subscribers connected to one center.
The leather adapter connects with MSAU for the help of two different straight lines.
Draw the structure and describe the functioning of LOM Token Ring based on one (decal) MSAU.
One - div. more
Dekіlka - (continued) ... With such two straight-lined lines, the link, as if it enters the main cable, can be connected to the MSAU in the ring (Fig. 3.3), on the side of a single-straight main cable, as shown in Fig. 3.2.
The LAN skin node receives a frame from the next node, adjusts the equal signals to the nominal ones, and transmits the frame to the advancing node.
The transmission frame can be sent as a marker, which is a special service 3-byte frame. Vuzol, which is a marker, has the right to transfer data.
If the RS needs to transmit a frame, then the adapter checks for the appropriate marker, and then converts it to a frame to avenge the data generated by the protocol of a similar level, and transfers it to the measure. The packet is transmitted by the number of adapters to the adapter until it reaches the addressee, which can be inserted into a new bit to confirm that the frame has been received by the addressee, and retransmit it in the measure. The package is carried on as soon as it turns to the higher-order office, which checks the correctness of the transfer. If the frame is transferred to the addressee without pardon, the node passes the token to the advancing node. In this way, in LOM with the transfer of the marker, it is impossible to block frames.
Why does the physical topology of the LOM Token Ring have a logical topology?
The physical topology of Token Ring can be implemented in two ways:
1) "star" (Fig. 3.1);
The logical topology of all methods is "kilce". The packet is transmitted from the node to the node along the ring, the docks of the wines do not turn around at the hubs, the de wines of the generations.
There are possible options for the structure of the LOM Token Ring.
1) "star" (Fig. 3.1);
2) "wider ring" (Fig. 3.2).
A short description of the functional organization of the LOM Token Ring. Div #93
Understanding the function of the active monitor in LOM Token Ring.
During the initialization of the LOM Token Ring, one of the working stations is assigned as active monitor , on which additional control functions are supposed to be used in the ring:
timchasovy control in the logical cycle with the method of revealing situations associated with the insertion of the marker;
molding a new marker after revealing the insertion of the marker;
molding of diagnostic frames for songs.
When the active monitor goes out of tune, a new active monitor is assigned with a few other PCs.
Which mode (method) of transferring the token is victorious in LOM Token Ring with a speed of 16 Mb/s?
To increase the productivity of the Token Ring network with 16 Mbps bandwidth, these titles are awarded early token pass mode (Early Token Release - ETR), in which the RS transmits an early RS token immediately after the transmission of the frame. With this, the attacking RS is able to transmit its own frames, not counting on the completion of the transmission of the external RS.
Recycle types of frames that are recycled in the SCRAP Token Ring.
marker; data frame; the sequence is completed.
Draw and explain the format of the marker (data frame, sequence completed) LOM Token Ring.
Marker Format
KO - terminal obmezhuvach - [J | K | 1 | J | K | 1 | PC | GO]
Data Frame Format
SPK - starting sequence of the frame
ALE - cob sheather - [J | K | 0 | J | K | 0 | 0 | 0]
AP - access control - [P|P|P|T|M|R|R|R]
QC - personnel management
AN - addresses of recognition
AI - addresses of dzherel
Dani - field of data
CS - checksum
PKK - a sign of the end of the frame
KO - terminal obmezhuvach
SC - frame status
Sequence format completed
The structure of the "pass through access" field of the LOM Token Ring frame.
UD- access control(Access Control) - may have the following structure: [ P | P | P | T | M | R | R | R ] de PPP - bit priority;
the lace adapter can give priority to the marker and frames of these data records in the field of battles, the priority is equal to the priority of the visual numbers like 0 to 7 (7 is the highest priority); The RS has the right to transfer the notification to that person, if the authority’s priority is not lower than the priority of the marker, which won; T- marker bit: 0 for marker and 1 for frame data; M- monitor bit: 1, i.e. a frame of transmissions by the active monitor and 0 - otherwise; removing by the active monitor the frame with the monitor bit, equal to 1, means that the marker was sent to the LOM without knowing the addressee; RRR- bits of reservation vikoristovuyutsya at once from bits to priority; RS can reserve further away from the margins, placing the value of its priority in the reservation, as the priority is higher for the current value of the reservation field;
after that, if the transmitting node, having taken the frame of data, turned around, forms a new marker, then sets the priority to the same value of the reservation field in the frame taken before it; in this order, the token will be transferred to the node, which will set the highest priority for the reservation field;
Assigning priority bits (token bit, monitor bit, reservation bit) to the "Access check" field of the LOM Token Ring marker. Div. more
Why is MAC's personnel equal to LLC's personnel?
QC- personnel management(Frame Control - FC) determines the frame type (MAC or LLC) and MAC control code; one-byte field to replace two areas:
De FF- Format (type) of a frame: 00 - for a frame of MAC type; 01 - for cadru equal LLC; (values 10 and 11 are reserved); 00 - Non-victorious reserve discharges; CCCC- MAC MAC frame code (Physical Control Field), which type (assigned by the IEEE 802.5 standard) of the required MAC equal frames should be assigned;
Which dataframe field indicates the validity of the MAC type (LLC)? At the field of KK (div. vishche)
Dovzhina data fields in the frames of the LOM Token Ring.
there is no special exchange for data fields, although it is practically impossible to blame it for a permissible hour of employment for a lesser working station and become 4096 bytes and can reach 18 Kbytes for a transfer with a speed of 16 Mbit / s.
How about additional information and now to take revenge on the last distributor of the Token Ring frame?
KO - terminal obzhuvach, to avenge, cream of the unique sequence of electrical impulses, two more areas of wounding 1 bit of skin:
bit of intermediate frame (Intermediate Frame), which accepts the following values:
1, as this frame is part of a multi-packet transmission
0, so the frame is left alone;
bit of revealed pardon (Error-detected), which is set to 0 at the moment the frame is created in the cell and there may be changes in the value of 1 when a pardon occurs when passing through the nodes of the mesh; after the next frame is retransmitted without error control at the next nodes until reaching the node of the dzherel, which should be re-transmitted to the frame;
How does the Token Ring measure function, how does the bit of pardon shown in the end frame of the distribution frame have a value of 1?
after the next frame is retransmitted without error control at the next nodes until reaching the node of the dzherel, which should be re-transmitted to the frame;
The structure of the "packet status" field of the data frame LOM Token Ring.
SC- (Stan) frame status(Frame Status - FS) - one-byte field that contains 4 reserved bits (R) and two internal fields:
bit (indicator) address recognition (A);
bit (indicator) copy of the package (C): [ ACRRACRR]
Since the checksum does not contain the SP field, the skin one-byte field is duplicated in bytes to guarantee the reliability of the data.
The transmission unit is installed 0 bits Aі W.
Priymalny vuzol A in 1.
If after copying the frame to the buffer of the receiving node, no pardons were detected for the frame, then bit W also installed at 1.
In this order, signifying a successful transfer to the frame and turning the frame to the dzherel with bits: A=1 i W=1.
A = 0 means that there is no more destination station in the measure, or the RS has gone out of tune (vimknena).
A = 1і W=0 means that a pardon was given on the way to the frame from the dzherel to the addressee (in case of this, it will also be inserted in 1 bit of the pardon of the last distributor).
A = 1, C = 1і bit of pardon display = 1 means that the pardon was on the return path of the frame from the addressee to the dzherel, after the frame was successfully accepted by the destination node.
About how to check the value of "address recognition bit" ("bit copying the packet to the buffer"), what is the value of 1 (0)?- Div. more
Is the maximum number of stations in one station LOM Token Ring expensive...?-256
Why is the maximum cost between stations in LOM Token Ring?
The maximum allowance between stations is to fall in the type of medium.
(line link) and fold:
100 meters - for twisted bets (UTP category 4);
150 meters - for twisted bets (IBM type 1);
3000 meters - for a fiber-optic bagatomode cable.
Advantages and shortfalls of Token Ring.
Benefits of Token Ring:
the number of conflicts in the middle of data transfers;
bezpechuєtsya guarantees hour access for all koristuvachіv merezhі;
Token Ring network works well and at high traffic, right up to 100% traffic, on the Ethernet port, even if the traffic is 30% and more time to access; tse is even more important for the measure of the real hour;
a larger allowable size of data that is transmitted in one frame (up to 18 Kbytes) in a single Ethernet connection, ensuring more efficient functioning of the media when transmitting large data communications;
the real speed of data transmission in Token Ring networks can be higher, lower in the case of the primary Ethernet (the real speed is due to the features of the equipment and adapters and the computer code in the network).
Shortfalls of Token Ring:
more high versatility of Token Ring paired with Ethernet, scalables:
more expensive adapters via the folding Token Ring protocol;
add-ons for cleaning concentrators MSAU;
smaller sizes of Token Ring, connected with Ethernet;
the need to control the strength of the marker.
Do any LOM have daily conflicts in the middle of data transmission (are there guarantees for access to all short-term employees)?
On a LAN with token access
Brief description of the FDDI LOM.
The maximum number of stations near the kiltsі is 500.
The maximum length of the road is 100 km.
The transmission medium is a fiber optic cable (it is possible to stop betting twists).
The maximum allowance between stations to deposit according to the type of medium that is transmitted, and to become:
2 km - for a fiber-optic bagatomode cable.
50 (40?) km - for fiber-optic single-mode cable;
100 m - for spin betting (UTP category 5);
100 m - for twisted bets (IBM type 1).
The access method is marker.
Transmission speed - 100 Mb/s (200 Mb/s for duplex transmission mode).
The fence on the fenced house of the fence is lined with the fence for the hour of the second passage of the signal with a ring to secure the maximum allowable hour of access. The maximum distance between subscribers is determined by the extinction of signals at the cable.
What does the abbreviation FDDI mean?
FDDI (Fiber Distributed Data Interface) is one of the first high-end technologies of LOM.
Designated by FDDI.
Standard FDDI orientations high speed transmission - 100 Mbit/s. This standard is designed in such a way that it is as close as possible to the IEEE 802.5 Token Ring standard. A small capacity according to the standard is due to the need to ensure a greater speed of transmission on a large scale.
FDDI technology transmits optical fiber as a transmission medium that ensures:
high arrogance;
flexible reconfiguration;
high speed of data transmission – 100 Mbit/s;
large distances between stations (for multimode fiber - 2 km; for single-mode fiber with different laser diodes - up to 40 km; maximum length of all lines - 200 km).
How are building passes secured by FDDI CROP?
For now, the next step is to designate that foldable Ethernet configurations with four segments can be installed in the industry of two main types:
- Repeater hubs (habi) - dialing repeaters and in no way logically subdivides the segments connected to them;
- Switches transmit information between segments, but do not transmit conflicts from segment to segment.
When there are more folding commutators, conflicts in other segments are spread on the space, near the segments themselves, but do not expand through the mesh, as in times of blocking more simple repeater hubs. This may be important for the choice of the topology of the Ethernet network, because the differences between the CSMA/CD access methods in the CSMA/CD access method convey the presence of conflicts and that difference, moreover, the total length of the network is still determined by the size of the conflict zone, the area of conflict (domain collision). In this way, shutting down the repeater concentrator does not subdivide the conflict zone, at the same time as the skin concentrator, which commutes, divides the conflict zone into parts. At the time of blocking the commutator, it is necessary to evaluate the praxis for the skin segment of the merezhі okremo, and in case of different repeater concentrators - for the merezhі zagalom.
Really, repeater concentrators zastosovuyutsya more often, stink shards are simpler and cheaper. That's why it's up to me to find out about them myself.
When choosing this Ethernet configuration rating, two main models will be victorious.
Model Rules 1
The first model formulates a set of rules, which are necessary for the designer of the measure when connecting four computers and segments:
- Repeater or concentrator, connections to the segment, decrease by one the maximum allowable number of subscribers that are connected to the segment.
- The latest path between two subscribers is guilty of including no more than five segments, four concentrators (repeaters) and two transceivers (MAU).
- If the path between subscribers consists of five segments and four concentrators (repeaters), then the number of segments, up to which subscribers are connected, is not guilty of rehashing three, but the responsibility of segments is simply to call them concentrators (repeaters). Tse already zgaduvane "rule 5-4-3".
- If the paths between subscribers are composed of several segments and three concentrators (repeaters), then the following must be considered:
- the maximum length of the fiber optic cable of the 10BASE-FL segment, which connects between the concentrators (repeaters), is not responsible for overhanging 1000 meters;
- the maximum length of the fiber optic cable of the 10BASE-FL segment, which connects hubs (repeaters) with computers, is not responsible for overhanging 400 meters;
- Computers can be connected to all segments.
You can be praised for vikonannya retelling of the rules, so that the measure will be prudent. The annual supplementary roses are not necessary for this kind of person. It is important that the application of these rules guarantees the acceptable amount of obstruction to the signal of the fence.
When organizing the interaction of nodes in local networks, the main role is assigned to the protocol of the channel level. However, in order for the channel layer to be able to intersect with these tasks, the structure of local networks can be fully defined, for example, the most popular channel layer protocol - Ethernet - for parallel connection of all nodes of the network to the coax cable. A similar pidkhid, which is similar to the most simple structures of cable networks between computers of local lines, having given the main method, they set before themselves the retailers of the first local lines in the other half of the 70s. Tsya meta was supposed to be simple, that cheap solution for the association of a few dozen computers, which are located in the boundaries of one life at the counting line.
The development of Ethernet technology has created high-performance options: IEEE802.3u/Fast Ethernet and IEEE802.3z/Gigabit Ethernet.
Fast Ethernet technologyє evolutionary development of the classic Ethernet technology. Її main advantages є:
1) increase in the throughput capacity of the segment in the short term up to 100 Mb/s;
2) saving to the method of double access to Ethernet;
3) saving of the mirror-like topology of the network and support of the traditional data transmission mediums – twisted parity of the fiber optic cable.
Зазначені властивості дозволяють здійснювати поступовий перехід від мереж 10Base-T - найбільш популярного на сьогоднішній день варіанта Ethernet - до швидкісних мереж, що зберігають значну наступність з добре знайомою технологією: Fast Ethernet не вимагає докорінного перенавчання персоналу та заміни обладнання у всіх вузлах мережі. The official standard 100Base-T (802.3u) has established three different specifications for the physical layer (in terms of the OSI seven-layer model) to support the upcoming types of cable systems:
1) 100Base-TX for two-pair cable on unshielded twist pair UTP Category 5, or shielded twist pair STP Type 1;
2) 100Base-T4 for unshielded twist pair cable UTP Category 3, 4 or 5;
3) 100Base-FX for multimode fiber optic cable.
Gigabit Ethernet 1000Base-T, based on torsion pair and fiber optic cable. Small Gigabit Ethernet technology is the sum of 10 Mbps and 100 Mbps Ethernet, it is possible to easily switch to this technology without investing large sums in software, cable structure and staff training.
Gigabit Ethernet technology is an extension of IEEE 802.3 Ethernet that uses the same packet structure, format, and support for the CSMA/CD protocol, full duplex, flow control, and more, but theoretically, ten times more productivity. CSMA/CD (Carrier-Sense Multiple Access with Collision Detection - multiple access with carrier control and detection of collisions) is a technology for multiple access to the global environment in a local computer network with collision control. CSMA/CD is considered to be decentralized vipadkovyh methods. Vіn vikoristovuєtsya as in the standard type of Ethernet, as well as in the high-width type (Fast Ethernet, Gigabit Ethernet). It is also called the mesh protocol, which uses the CSMA/CD scheme. The CSMA/CD protocol works on the channel level of the OSI model.
Gigabit Ethernet - secure transmission speed of 1000 Mb/s. Use the following modifications to the standard:
1) 1000BASE-SX - a fiber optic cable is installed from a long wave of 850 nm light signal.
2) 1000BASE-LX - a fiber optic cable is twisted with a long wave length of the 1300 nm light signal.
Ethernet, all the way down to other less popular devices.Ethernet and Fast Ethernet adapters
Adapter characteristics
Merezhevі adapters (NIC, Network Interface Card) Ethernet and Fast Ethernet can be connected to a computer through one of the standard interfaces:
- ISA bus (Industry Standard Architecture);
- PCI bus (Peripheral Component Interconnect);
- bus PC Card (Won PCMCIA);
Adapters, rozrakhovanі on the system bus (trunk) ISA, until recently, were the main type of adapters. The number of companies that produced such adapters was large, and the very same attachment of this type was found to be the cheapest. Adapters for ISA are available in 8 and 16 bits. 8-bit adapters are cheaper, and 16-bit adapters are smarter. Truthfully, the exchange of information on the ISA bus cannot be too fast (for the border - 16 MB / s, in reality - no more than 8 MB / s, and for 8-bit adapters - up to 2 MB / s). This adapters are Fast Ethernet, yaki vimagayut of ethnic robotics of great skims to the proportion, and it is not enough to vine. The ISA bus enters the past.
The PCI bus at once practically replaced the ISA bus and became the main computer expansion bus. It will ensure the exchange of 32-bit data and 64-bit data and use a high throughput building (theoretically up to 264 MB / s), which satisfies not only Fast Ethernet, but also Gigabit Ethernet. It is important that the PCI bus is found not only in IBM PC computers, but also in PowerMac computers. In addition, it will automatically configure Plug-and-Play. Maybe, the nearest future one will be more oriented to the PCI bus lace adapters. The lack of PCI in parallel with the ISA bus is due to the fact that the number of expansion slots in a computer is usually small (say 3 slots). Ale same mesh adapters connect to PCI directly.
The PC Card bus (old name PCMCIA) is currently only found in Notebook-class portable computers. On these computers, the internal PCI bus name should not be displayed. The PC Card interface transfers a simple connection to the computer of miniature expansion boards, and the speed of exchange between these boards is high. However, more and more portable computers are equipped with lace adapters, oskіlki mozhlivіst access to the merezhі becomes an invisible part of the standard set of functions. New adapters are connected to the computer's internal PCI bus.
When choosing twill adapter, oriented to that other bus, it is necessary, first of all, to switch over, what are the slots for expanding this bus in the computer, what to enter to the border. The next step is to evaluate the laboriousness of installing the adapter and the prospects for the release of boards of this type. The remainder may be needed at the time of the adapter's operation.
Zreshtoy, zustrichayutsya mesh adapters, which are connected to the computer through the parallel (printer) LPT port. The main advantage of such an approach is that for connecting adapters it is not necessary to open the computer case. In addition, in this case, the adapters do not occupy the system resources of the computer, such as the channels of the RAP, as well as the addresses of the memory and input/output devices. However, the speed of exchange of information between them and the computer in this way is significantly lower, lower with a different system bus. Until then, the stench takes more than a processor hour to exchange from a network, supporting the computer's robot.
In the rest of the hour, more and more computers are chirping, in which mesh adapters vbudovani at the system board. The benefits of such an approach are obvious: the coristuvach is not guilty of buying the adapter of the thread and installing it in the computer. It is enough to just connect the cable to the outer socket of the computer. However, it is not enough to say that a short-ranger cannot choose an adapter with the best characteristics.
To the other most important characteristics lace adapters you can see:
- adapter configuration method;
- expansion of the buffer memory installed on the board and the modes of exchange with it;
- the possibility of installing a permanent memory chip on the board for remote advancement (BootROM).
- the possibility of connecting the adapter to different types of transmission medium (vita pair, thin coaxial cable, fiber optic cable);
- the adapter vikoristovuetsya transfer speed as needed and the presence of the function її switching;
- possibility of blocking by the adapter in full-duplex exchange mode;
- the sum of the adapter (to be more precise, the adapter's driver) with the twists and turns of the software.
The configuration of the adapter was too short for the adapters that were allocated to the ISA bus. Transfer configuration adjusting the selection of system resources of the computer (input/output address, channels to interrupt and direct access to memory, buffer memory address and remote access). Configuring can be done with a path installed in the required position of jumpers (jumpers), or for the help of DOS-configuration programs ( Jumperless , Software configuration), which are added to the adapter. When such a program is launched, it prompts you to install the hardware configuration for the help of a simple menu: select adapter parameters. This program allows you to rob self-test adapter. The selected parameters are stored in the independent memory of the adapter. In any case, when choosing parameters, it is necessary to unify conflicts with system outbuildings computer and with other expansion boards.
The adapter configuration can be configured automatically in Plug-and-Play mode when the computer is enabled. Modern adapters sound to support the same mode, so you can easily install a koristuvach.
For the simplest adapters, the exchange from the internal buffer memory of the adapter (Adapter RAM) is carried out through the address space of the input/output device. It is not necessary for this person to configure memory addresses. The base address of the buffer memory used in memory mode must be specified. Vin is assigned to the upper memory area of the computer (
The widest range of standard Ethernet tethers is the Ethernet tether. Vaughn appeared in 1972 rock, and in 1985 rock became the international standard. Її accepted by the largest international organizations for standards: Committee 802 IEEE (Institute of Electrical and Electronic Engineers) and ECMA (European Computer Manufacturers Association).
The standard is called IEEE 802.3 (read in English as "eight oh two dot three"). Vіn assigns multiple access to a mono channel type bus with conflict detection and transmission control, so with a CSMA / CD access method, which is already a guess.
The main characteristics of the cob standard IEEE 802.3:
Topology - bus;
· Transmission medium - coaxial cable;
· Transmission speed - 10 Mb/s;
· the maximum length of the merezha is 5 km;
· maximum number of subscribers – up to 1024;
· Dovzhina segment merezhі - up to 500 m;
· Number of subscribers per segment – up to 100;
· Access method - CSMA / CD;
· Vuzkosmugov transmission, without modulation (monochannel).
Strictly seeming, between IEEE 802.3 and Ethernet standards, there are some insignificant details, but you should not guess about them.
Merezha Ethernet is currently the most popular in the world (over 90% of the market), it is so out of the question and to get rid of the nearest rock. What a significant world was taken by those who, from the very beginning of the characteristics, parameters, protocols of the measures, were recognized, after which the great number of virobniks in the world began to release Ethernet equipment, I will sum up myself.
The classic Ethernet cable has a 50-ohm coaxial cable of two types (thin and thin). However, in the last hour (since the beginning of the 90s) the largest version of Ethernet appeared, as a victorious as the medium of transmission of twisted bets. A standard has also been drawn up for laying in a fiber optic cable. For vakhuvannya tsikh zmin to cob standard IEEE 802.3 was zrobleno vіdpovіdnі dаvannya. In 1995, a new standard appeared for a larger version of Ethernet, which works on a speed of 100 Mbit / s (the so-called Fast Ethernet, IEEE 802.3u standard), which twisted a pair or a fiber optic cable as a transmission medium. In 1997, a 1000 Mbit/s version was released (Gigabit Ethernet, IEEE 802.3z standard).
The standard topology bus is becoming more and more popular with topologies like passive star and passive tree. At the same time, the number of repeaters and repeater concentrators is transmitted, which separates the different parts (segments) of the merezhi. Through war, a tree-like structure can form on segments of various types (Fig. 7.1).
Like a segment (parts of a merezhі) can be a classic bus or a single subscriber. For bus segments, a coaxial cable is used, and for changing a passive star (for connecting to a single computer hub), a pair of fiber optic cables is twisted. The main one was completely eliminated as a result of the topology - because it did not have closed paths (dependence). In fact, when all subscribers are connected to the physical bus, the signals from the dermal signal expand on all sides and do not turn back (like in the ring).
The maximum length of the wire cable in general (maximum signal path) theoretically can reach 6.5 km, but practically does not exceed 3.5 km.
Rice. 7.1. Classic Ethernet network topology.
The Fast Ethernet network does not have a physical bus topology, it is only a passive star or a passive tree. Before that, Fast Ethernet has a lot of zhorstkіshі vomogi to the boundary line of the border. Even with a 10-fold increase in the speed of transmission and saving the format of the package, the minimal length of the package becomes ten times shorter. Thus, 10 times the permissible value of the signal passing hour is changed over time (5.12 µs versus 51.2 µs in Ethernet).
For transmission in an Ethernet network, the standard Manchester code is used.
Access to the Ethernet network is controlled by the CSMA/CD vipadkovym method, which ensures the equality of subscribers. At the merezha, there are packages of changeable dozhina.
For an Ethernet network, which operates at a speed of 10 Mb/s, the standard defines the following main types of segments in the network, oriented to different media of transmission of information:
10BASE5 (common coaxial cable);
· 10BASE2 (thin coaxial cable);
10BASE-T (vita pair);
· 10BASE-FL (fiber optic cable).
The name of the segment includes three elements: the number "10" means the speed of transmission of 10 Mbit / s, the word BASE - transmission to the main frequency mix (that is, without modulating the high-frequency signal), and the remaining element - the allowable length of the segment: "5" - 500 meters, " 2" - 200 meters (more precisely, 185 meters) or the type of connection line: "T" - twisted pair (English "twisted-pair"), "F" - fiber optic cable (English "fiber optic").
So for the Ethernet network itself, which works on the speed of 100 Mbit / s (Fast Ethernet), the standard defines three types of segments, which are considered by the types of transmission medium:
100BASE-T4 (quad twisted pair);
· 100BASE-TX (double twisted pair);
· 100BASE-FX (fiber optic cable).
Here the number "100" means the speed of transmission of 100 Mbit / s, the letter "T" - a twisted pair, the letter "F" - a fiber optic cable. Types 100BASE-TX and 100BASE-FX can sometimes be combined under the names of 100BASE-X, and 100BASE-T4 and 100BASE-TX - under the names of 100BASE-T.
Merezha Token-Ring
The Token-Ring (marker ring) was propagated by IBM in 1985 (the first version appeared in 1980). The won was assigned to the union of all types of IBM computers. Even though the fact that I support IBM, the largest manufacturer of computer technology, to talk about those who need to add special respect. But not less important are those that Token-Ring is currently in accordance with the international standard IEEE 802.5 (even though Token-Ring and IEEE 802.5 are insignificant). Tse to put the measure on one level for the status of Ethernet.
The development of Token-Ring is a great alternative to Ethernet. If you want Ethernet to close the network at once, Token-Ring cannot be used hopelessly old. Over 10 million computers in the whole world are united by a network.
Merezha Token-Ring may have a topology, although the calls will be more predictable. For this reason, some subscribers (computers) do not come to the measure without intermediary, but through special concentrators for rich station access (MSAU and MAU - Multistation Access Unit). Physically, the mesh establishes a mirror-kilce topology (Fig. 7.3). In fact, the subscribers are united all the same in the ring, so that one of them transmits information to one land subscriber, and receives information from another.
Rice. 7.3. Zirkovo-kiltseva topology of the Token Ring network.
As the medium of transmission in the IBM Token-Ring line, a twisted pair of unscreened (UTP) and screened (STP) pairs were interlocked, and then there were options for equipment for a coaxial cable, as well as for a fiber optic cable in the FDDI standard.
The main technical characteristics of the classic Token-Ring variant:
· Maximum number of concentrators type IBM 8228 MAU - 12;
· the maximum number of subscribers for the Merezha is 96;
· the maximum length of the cable between the subscriber and the concentrator is 45 meters;
· maximum cable length between concentrators – 45 meters;
· the maximum length of the cable, which connects all concentrators - 120 meters;
· Speed of data transmission - 4 Mb/s and 16 Mb/s.
The necessary characteristics can be seen until the end of the year for non-screened twists of the bet. Even though the middle of the transmission is victorious, the characteristics of the border can be changed. For example, with different screened twists of the bet (STP), the number of subscribers can be increased to 260 (zamіst 96), the length of the cable - up to 100 meters (zamіst 45), the number of concentrators - up to 33, and the total amount of core - concentrate, up to 200 meters. Fiber optic cable allows you to extend the length of the cable up to two kilometers.
For transmission in the Token-Ring, a biphasic code is required (more precisely, this option with a binding transition at the center of the bit interval). As in the be-yakіy zirkopodіbnіbnіy topologii, zhdnih dodatkovyh zahodo elektricheskogo uzhodzhennia that zіrkopodіbnіy zemlіnії іn't nebіbіl. Uzgodzhennya vykonuetsya equipment mesh adapters and concentrators.
For connecting cables, Token-Ring has RJ-45 roses (for non-cabled betting twists), as well as MIC and DB9P. Conducting at the cable, one-time contacts of roses are connected (this is why "straight" cables are called so).
Merezha Token-Ring in the classic version comes with Ethernet merezha both for the allowable size and for the maximum number of subscribers. As far as the speed of transmission, none of the Token-Ring versions are available for 100 Mb/s (High Speed Token-Ring, HSTR) and 1000 Mb/s (Gigabit Token-Ring). Companies that promote Token-Ring (among them IBM, Olicom, Madge) should not try to think of us as their own, looking at it as a good competitor to Ethernet.
In pairs with Ethernet equipment, Token-Ring equipment is expensive, but there is a folding method for managing the exchange, so Token-Ring does not have such a wide width.
However, on the Ethernet interface, Token-Ring networks are much more likely to have a high profitability rate (more than 30-40%) and guarantee an hour of access. It is necessary, for example, at the borders of a common confession, in some obscurity, the reaction to the outward weather can lead to serious accidents.
The Token-Ring network uses a classic token access method, so that a token constantly circulates around the ring, so that subscribers can receive their data packets (div. Fig. 4.15). It is important to note that the number of links is so important, as the number of conflicts, but also the shortcomings, it is necessary to control the integrity of the marker and the staleness of the function of the link to the skin subscriber (in case of malfunctions, the subscriber is forced to switch on).
Token-Ring packet transmission time limit 10 ms. For the maximum number of subscribers 260, the last cycle of the warehouse operation is 260 x 10 ms = 2.6 s. In one hour, 260 subscribers will be able to transfer their packets (so, obviously, they can transfer). For tsey hour vіlny marker obov'yazkovo didde to the skin subscriber. The same interval is the upper time limit for Token-Ring access.
Merezha Arcnet
Merezha Arcnet (or ARCnet in English Attached Resource Computer Net, computer network of resources) is one of the oldest merezh. Vaughn was broken up by the Datapoint Corporation back in 1977. International standards for the measure of the day, although it is itself considered the ancestor of the method of marker access. Regardless of the current standards, until recently (1980 - 1990) the Arcnet network was popular, and seriously competed with Ethernet. A lot of companies have made equipment for this type of merchandise. But at the same time, the versatility of the Arcnet hardware is practically pinned down.
Among the main advantages of the Arcnet measure, paired with Ethernet, you can name the value of the access time, the high reliability of the connection, the ease of diagnostics, and the low availability of adapters. To the most small amounts, one can see the low speed of transmission of information (2.5 Mb/s), the addressing system and the format of the packet.
For transmission in Arcnet measure, it is necessary to complete a logical code, for which a logical unit has two pulses over a bit interval, and a logical zero has one pulse. Obviously, this code, which is self-synchronizing, which means more cable bandwidth, lower Manchester.
As the medium of transmission of the wire, a coaxial cable with a flexible support of 93 Ohm is used, for example, brand RG-62A/U. Variants with a twisted pair (screened and non-screened) did not have a wide width. There were proponations and options on fiber optic cable, but the stench also did not turn Arcnet.
Like the topology of the Arcnet network, the classic bus (Arcnet-BUS), as well as the passive star (Arcnet-STAR). Concentrators (habi) are found at the vicory. It is possible to connect for additional concentrators of bus and mirror segments in a tree-like topology (like in Ethernet). A smutty obmezhennya - topology is not guilty of closed paths (zashmorg). One more exchange: the number of segments, joined by the last lancet for additional concentrators, is not guilty of revisiting the three.
Also, the topology of the Arcnet network can look like this (Fig. 7.15).
Rice. 7.15. Topology of the Arcnet network to the bus type (B - adapters to work on the bus, S - adapters to work at the rear).
The main technical characteristics of the Arcnet measure are the same.
· Transmission medium - coaxial cable, twisted pair.
· The maximum length of the fence is 6 kilometers.
· The maximum cable length from the subscriber to the passive hub is 30 meters.
· The maximum cable length from the subscriber to the active hub is 600 meters.
· The maximum cable length between active and passive hubs is 30 meters.
· The maximum cable length between active hubs is 600 meters.
· The maximum number of subscribers for the Merezha is 255.
· The maximum number of subscribers on the bus segment is 8;
· The minimum distance between subscribers at the bus is 1 meter.
· The maximum length of the tire segment is 300 meters.
· Transmission speed – 2.5 Mb/s.
When folding folding topologies, it is necessary to make sure that the jamming of the signal width between subscribers does not exceed 30 µs. The maximum attenuation of the signal in the cable at a frequency of 5 MHz is not guilty of overshooting 11 dB.
The Arcnet merge has a token access method (method of transfer of rights), but it is similar to the Token-Ring merge. The closest method to what is passed in the IEEE 802.4 standard.
So, just like the Token-Ring option, Arcnet conflicts are turned off for the most part. Like and be-yak, the marker on the Arcnet network is good for profitability and guarantees the value of the hour for access to the network (on the Ethernet login). The last hour of bypassing all subscribers becomes 840 ms as a marker. Obviously, this very interval sets the upper time interval for access to the border.
The marker is formed by a special subscriber - the controller of the measure. It is a subscriber with a minimum (zero) address.
Merezha FDDI
Merezha FDDI (in English Fiber Distributed Data Interface, fiber optic distribution of the data interface) is one of the new developments of local standards. The FDDI standard has been approved by the American National Standards Institute ANSI (ANSI specification X3T9.5). Then the ISO 9314 standard was adopted, which conforms to the ANSI specifications. The riven of standardization of the measure is high.
In view of other standard local networks, the FDDI standard is increasingly focused on the highest transmission speed (100 Mbit/s) and the most promising fiber optic cable. Therefore, in this case, the retailers were not surrounded by the framework of the old standards, which focused on low speed and electric cable.
The choice of fiber optics as the medium of transmission, having distinguished such advantages of the new medium, as a high degree of deviation, maximum secrecy of information transmission and excellent galvanic decoupling of subscribers. The high speed of transmission, as in the case of a fiber optic cable, it is much easier to reach, allowing you to make a lot of tasks that are inaccessible to lesser wires, for example, the transmission of images at a real scale for an hour. In addition, the fiber optic cable easily overcomes the problem of data transmission for a few kilometers without retransmission, which allows you to be large beyond the borders of the borders, which can saturate the city of the city and may, with all the transfer of the local borders (the low border). All this indicated the popularity of FDDI, although it is not as widespread as Ethernet and Token-Ring.
The FDDI standard is based on the method of token access, transferred by the international standard IEEE 802.5 (Token-Ring). Bearing authority in accordance with the standard, it is necessary to ensure high security of transmission on a large scale. Topology of FDDI network - ce kіlce, the most appropriate topology for fiber optic cable. The Merezhi has two RIZNEPRAMOVAMOVAMOVOVOLOKOL KABELI, one call to the reserve, one of the rizhennya is permitted by the transmission of іnformas (one -time by the twice) 100 Mb/s). Zaryano-Kiltseva topology with concentrators included in the ring (like Token-Ring) is also established.
Main technical characteristics of FDDI.
· The maximum number of subscribers in the merezhі is 1000.
· The maximum length of the fence is 20 kilometers.
· The maximum distance between the subscribers of the merezhі is 2 kilometers.
· The transmission medium is a multimodal fiber optic cable (it is possible to stop the electric torsion of the bet).
· Access method - Marker.
· Transmission speed – 100 Mb/s (200 Mb/s for duplex transmission mode).
The FDDI standard has significant advantages, compared with the previously considered measures. For example, Fast Ethernet merging, which can have the same throughput of 100 Mb/s, cannot be compared with FDDI beyond the allowed merging sizes. Before that, the marker access method FDDI provides for CSMA/CD access guarantees for an hour of access and the same number of conflicts for any level of vanity.
Interconnection to the gale house of the fence 20 km away is connected not with the extinguishing of signals at the cable, but with the need for interception of the hour of the complete passage of the signal by the ring to ensure the maximum permissible hour of access. And the maximum axis between subscribers (2 km with a multimode cable) is due to the fact that the signals at the cable are extinguished (it is not guilty of overshooting 11 dB). There is also the possibility of blocking a single-mode cable, and in this case, between subscribers, it can reach 45 km, and the total length of the cycle is 200 km.
It is also the implementation of FDDI on an electric cable (CDDI - Copper Distributed Data Interface or TPDDI - Twisted Pair Distributed Data Interface). This cable has a category 5 cable with RJ-45 sockets. The maximum distance between subscribers in any given day can be no more than 100 meters. Varity of possession of a wire on an electric cable at a small scale. However, this version of the network no longer has such obvious advantages over competitors, like FDDI fiber optics. Electrical versions of FDDI are standardized more expensive than fiber optics, so the totality of the possession of other types is not guaranteed.
For transmission to FDDI, a 4V / 5V code is required, which is specially expanded to this standard.
The FDDI standard for achieving high-density communication between two types of subscribers:
· Subscribers (stations) of class A (subscribers of a mobile connection, DAS - Dual-Attachment Stations) are connected to both (internal and external) networks. With this implementation, the possibility of exchange with a speed of up to 200 Mbit / s is realized, or a reservation is made for a tie cable (with a reduced main cable, a reserve cable is used). The equipment of this class is located in the critical parts of the fence.
· Subscribers (stations) of class B (single-attachment subscribers, SAS - Single-Attachment Stations) are connected to only one (outer) ring of the network. The stench is simple and cheap, comparable with class A adapters, but you can’t imagine their possibilities. At the edge of the stink, only through the concentrator or bypass switch can be switched on, which can be used in case of accidents.
We will surround subscribers (computers, terminals, etc.) at the network with Wiring Concentrators, the inclusion of which allows you to pick up all connection points in one place with the method of monitoring the work of the network, diagnosing malfunctions and simplifying reconfiguration. In case of congestion of cables of various types (for example, fiber optic cable and torsion of a bet), the concentrator also loses the function of converting electrical signals into optical ones. The concentrators also use a sub-connection (DAC - Dual-Attachment Concentrator) and a single connection (SAC - Single-Attachment Concentrator).
An example of a configuration of FDDI representations in fig. 8.1. The principle of adding a building to a fence is illustrated in Fig. 8.2.
Rice. 8.1. Butt configuration FDDI.
On the view of the access method, which is proponated by the IEEE 802.5 standard, FDDI will stop the so-called multiple token transfer. If in the case of the Token-Ring merge a new (valid) token is transmitted by the subscriber only after the return to the new packet, then the FDDI new token is transmitted by the subscriber immediately after the completion of the transfer of the packet to him (similar to how to work with the ETR method in the Token-Ring merge) ring).
At the end of the line, regardless of the obvious prevails of FDDI, the measure is not wide-width, which is tied to the top rank with a high variety of її equipment (about a few hundreds and a thousand dollars). The main sphere of FDDI contagion at a time is the basic, supporting (Backbone) lines, which should be combined with a sprat. FDDI is also installed for hard work stations and servers, which require a high-speed exchange. It is believed that the Fast Ethernet network can outperform FDDI, fiber optic cable protection, marker management method and record allowable network size to set FDDI ahead of competition. And in bets, if the variability of the equipment is less important, it is possible to install the version of FDDI on the basis of a twisted bet (TPDDI) on non-critical sites. In the meantime, the versatility of FDDI hardware may vary greatly due to the release rate.
Merezha 100VG-AnyLAN
Merezha 100VG-AnyLAN - is one of the remaining retailers of high-width local merezha, which recently appeared on the market. It is in compliance with the international standard IEEE 802.12, the level of standardization is high.
The main advantages are the high exchange rate, relatively low equipment variability (approximately twice as expensive for the most popular 10BASE-T Ethernet network), the centralization method for managing the exchange without conflicts, as well as the summation of Ethernet Token formats.
In the name of the 100VG-AnyLAN measure, the number 100 is based on the speed of 100 Mb/s, the letters VG mean a cheap non-cable twisted pair of category 3 (Voice Grade), and AnyLAN (whether or not a measure) means that the measure is summed with two of the widest measures.
Main technical characteristics of 100VG-AnyLAN:
· Transmission speed – 100 Mbit/s.
· Topology - a star with the possibility of growing (tree). The number of cascading concentrators (hubs) - up to 5.
· Access method - centralization, conflict-free (Demand Priority).
· Transmission medium – double shielded twisted pair (UTP cable category 3, 4 or 5), double twisted pair cable (UTP cable category 5), double shielded twisted pair cable (STP), as well as fiber optic cable. At the same time zdebіlshgo widened chotirivіrna twisted pair.
· The maximum length of the cable between the concentrator and the subscriber and between the concentrators is 100 meters (for UTP cable of category 3), 200 meters (for UTP cable of category 5 and shielded cable), 2 kilometers (for fiber optic cable). The maximum possible size of the border is 2 kilometers (subject to allowable stunts).
· The maximum number of subscribers is 1024, recommended is up to 250.
Thus, the parameters of the 100VG-AnyLAN measure are close to those of Fast Ethernet. However, the main advantage of Fast Ethernet is the totality of the most advanced Ethernet network (in case of 100VG-AnyLAN, which one needs space). At the same time, the centralized management of 100VG-AnyLAN, which excludes conflicts and guarantees the boundary value of the access hour (which is not transferred to the Ethernet network), also cannot be dropped from the accounts.
The butt structure of the 100VG-AnyLAN measure is shown in fig. 8.8.
The 100VG-AnyLAN network is composed of a central (main, root) concentrator of level 1, which can be connected as a number of subscribers, and concentrators of level 2, which subscribers and concentrators of level 3 can be connected to their own line. In this merezha, the mother may have more than five such equals (in the cob variant, there were more than three). The maximum betting distance can be 1000 meters for non-canceled bet twists.
Rice. 8.8. The structure of the 100VG-AnyLAN.
For non-intelligent hubs of other networks (for example, Ethernet, Token-Ring, FDDI), 100VG-AnyLAN array hubs are smart controllers that provide access to the array. For whom the stink is constantly controlled and drunk, which is available at all ports. Concentrators accept packets as they come, and forward them only to such subscribers, as they are addressed. However, none of the stench of information is vibrated, so that it is not active to enter this way, but it is not a passive star. Hubs cannot be called full subscribers.
The skin from the concentrator can be used with Ethernet packet formats and Token-Ring. With this concentrator, all services are responsible for processing packages with only one format. For communication with Ethernet and Token-Ring networks, you need to do it, but it's easy to do it.
Concentrators may have one port of the upper level (for connecting to the concentrator of the higher level) and a few ports of the lower level (for connecting subscribers). As a subscriber, you can act as a computer (working station), server, location, router, switch. Another concentrator can come to the port of the lower river.
The skin port of the hub can be set to one of two possible operating modes:
· Normal mode of transferring to the subscriber, delivered to the port, only packets addressed especially to you.
· Monitor mode transmitting to the subscriber who arrived at the port, all packets, like a concentrator. This mode allows one of the subscribers to control the robot all the time (to override the monitoring function).
The method for accessing a 100VG-AnyLAN tier is typical for a tier with a mirror topology.
In case of a different four-twisted bet, the transmission over the skin of four twisted pairs is carried out with a speed of 30 Mbps. The total speed of transmission is 120 Mb/s. However, the basic information after using the code 5B/6B is transmitted only with a speed of 100 Mb/s. In this rank, the throughput of the cable can be no less than 15 MHz. For this purpose, we are satisfied with a cable with twisted pairs of category 3 (the bandwidth is 16 MHz).
Thus, 100VG-AnyLAN is an affordable solution for increasing transmission speed up to 100 Mb/s. However, there is not a lot of totality with the same standard measures, so farther away the share is problematic. Until then, on the FDDI board, there are no record-breaking parameters. More than anything, 100VG-AnyLAN is not respectful of the support of reputable companies and the high level of standardization will be left with just the butt of cіkavih technical solutions.
Speaking of the widest 100-megabit Fast Ethernet network, 100VG-AnyLAN secures the largest UTP category 5 cable (up to 200 meters), as well as a conflict-free exchange management method.