The plan of work for a degree of the master

1. The analysis of an existing corporate network of company SONED
1.1 Territorial structure of a network
1.2 Base technologies and architecture of a network
1.3 Means of an existing network
1.4 Statement of a problem(task) in modernizations of a network
2. Forecasting parameters of a network
2.1 The analysis of the existing and planned traffic
2.2 The analysis of demand for services of a network
2.3 A prediction of the plan and structure of a network
3. Modelling a network
3.1 A choice of architecture of a modernized network
3.2 A choice and optimization of topology of a network
3.3 A choice of base network technologies and environments of transfer
3.4 Development and optimization of circuits of the organization of levels of a corporate network
4. Technical realization of the project
4.1 Definition of stages and priorities at modernization of a corporate network
4.2 The analysis and a choice of communication lines and equipments TSSP
4.3 The analysis and a choice of the equipment of units of a corporate network
4.4 The analysis and a choice of terminals of networks of access
4.5 The organization of management by the modernized corporate network
5. The conclusion

Introduction

Has historically developed so, that the great bulk of networks, at least in Moldova, was created on technology 10Base-2 and 10Base-T. For today the basic types a LAN are the networks constructed on base of " twisted pair ". To this the basic accent(stress) in given clause(article) will be done(made) on rules of designing of networks of the standard 10Base-T, and also features and restrictions, накладываемые on these rules at their joint application with other standards (10Base-5, 10Base-2, 10Base-F, 100Base-TX, 100Base-T4 and 100VG-AnyLAN).
In the beginning some basic terms and definitions:
ﾷ Standard IEEE 802.3 (standard Ethernet) defines(determines) the local computer network as conflict area or the domain of collisions.
ﾷ A collision - destruction of a package of the data in the channel during transfer. When the unit sends a package, it(he) simultaneously checks, whether has taken place during transfer a collision. If the collision occurs, the units which have got in it(her) stop transfer, maintain a pause during a casual time interval and repeat transfer. Absence of detection of a collision specifies to unit, that transfer of a package has passed successfully.
ﾷ Time after which a package is guaranteed passes on liaison channels from a source up to the addressee not having undergone on ways of collisions refers to as " the maximal period of the circular reference(manipulation) of the message " (maximum round-trip time). This time defines(determines) the worst situation at which the package will pass from the unit - sender on one end of a network up to a place of occurrence of a collision on the other end of a network and thus a signal about a collision is guaranteed will reach unit - the sender.
ﾷ The geometrical sizes of a network which meet the requirements of " the maximal period of the circular reference(manipulation) of the message " and define(determine) conflict area. A LAN will function correctly only in that case when all its(her) units can be notified on a collision during the maximal period of the circular reference(manipulation).
Rules of designing of networks of the standard 10Base-5
I cannot understand, why even recently there come messages on installation of networks under the standard 10Base-5. In fact application of this standard now for installation new a LAN in my opinion is not justified financial, with technical the parties(sides), and for the decision of problems of association a LAN, usually economically and technologically more favourably application of technology 10/100Base-F. But time it occurs, it means " to somebody it is necessary " and necessary to state rules of application of this technology:
1. The network of the standard 10Base-5 can consist a maximum of five main segments.
2. Segments of a network incorporate among themselves repeaters. Their maximum quantity - 4.
3. Computers can be connected only to three segments of the main cable.
4. The maximal length of a segment - 500 m (lengths of cables of transceivers are not taken into account).
5. On the ends of a cable segment should be established терминаторы.
6. Connection of computers to the main cable is carried out with the help of the transceiver.
7. The maximal distance between a computer and the transceiver - 50 m.
8. The minimal distance between transceivers - 2,5 m.
9. A maximum quantity of computers on a cable segment - 100.
10. A maximum quantity of computers on all segments of a network - 1024.
11. The maximal general length of a network - 2500 m.
Examples of application of technology 10Base-5
Application of technology 10Base-5 on one coaxial segment

Fig. 1. "Classical" Ethernet (10Base-5)

1 example resulted on fig. "classical" Ethernet-á is so widely distributed in the literature, that, in my opinion, does not demand any comments.
Demonstration of opportunities of technology 10Base-5
On fig. 2 the variant of construction multisegment a LAN with application of technology 10Base-5 and multiport transceivers is represented. The example with multiport transceivers is resulted with the purpose to show that phenomenon, that "classical" Ethernet - the system having advanced enough base of accessories.

Fig. 2. Multisegment Ethernet, constructed with application of technology 10Base-5

Rules of designing of networks of the standard 10Base-2
The set of networks of the standard 10Base-2 has been constructed in second half 80 - the beginning 90 г.г. Now, as a rule, a scope of this standard are the main channels by means of whom the working groups constructed with application of technology 10Base-T are united, and also a small LAN, as a rule одноранговые and incorporating no more 10-ти (it is usual 3-5) computers. Wide application of technology 10Base-2 restrains insufficiently high reliability of a cable subsystem as a whole as systems with " the general(common) trunk ", and also that in practice she(it) has been discredited as a result of universal application at installation of the cables not specified for it that resulted in unstable work of the networks constructed with application of this kind of technology. Personally to me fell at results of application not simply improper cable under the geometrical characteristics, but even application of segments with wave resistance 75 and 100 ohm.
Rules of application of technology 10Base-2:
1. The network of the standard 10Base-5 can consist a maximum of five main segments.
2. Segments of a network incorporate among themselves repeaters (a maximum 4).
3. Computers can be connected only to three segments of the main cable. Two segments serve for increase in diameter a LAN.
4. Connection of computers is carried out with help Æ-коннекторов.
5. The maximal length of a segment - 185 m.
6. A used cable - RG-58 (wave resistance 50 ohm).
7. On the ends of a cable segment should be established терминаторы.
8. A maximum quantity of computers on a cable segment - 30 (taking into account connected to a cable, but not involved Æ-коннекторы).
9. A maximum quantity of computers on all segments of a network - 1024.
10. The minimal length of a cable segment - 0.5 m.
11. The maximal general length of a network - 925 m.
Examples of application of technology 10Base-2
Ethernet technologies 10Base-2 on one coaxial segment

Fig. 3. Ethernet the standard 10Base-2

Recently installation of new network Ethernet such as 10Base-2 on one coaxial segment (see fig. 3) - the unusual occurrence is enough. Sphere of the appendix of this technology there were only small offices, where quantity(amount) of computers seldom when more 5-ти.
Additional opportunities of technology 10Base-2
Restriction on quantity(amount) of computers on a segment (30) and on length of a segment (185 м) are serious enough an obstacle at planning a network of the sizes not that that two, and even one floor. However it is completely not necessary to entangle " the coaxial trunk " all premises(rooms). The technology 10Base-2 supposes application and star-shaped topology: on fig. 4 the variant of topology such as "star" which beams are шинными segments is submitted.

Fig. 4. A variant of expanded application Ethernet-á of the standard 10Base-2

Rules of designing of networks of the standard 10Base-T
The technology 10Base-T has been standardized only in 1990 (standard IEEE 802.3). 10Base-T provides construction a LAN by use of cable segments for creation of dot liaison channels (point-to-point links). Thus the basic topology becomes any more "trunk", as in 10Base-5 and 10Base-2, and "star". The geometrical sizes of the networks constructed by a variant 10Base-T as depend on attenuation of a signal in the transmitting environment and from time of distribution of a signal. The matter is that having defined(determined) other type of a cable, connectors and other topology of a network, 10Base-T there is same a Ethernet-ohm (in logic sense) and 10Base-5. In logic sense, the concentrator - Hub it simply a segment of a coaxial cable from technology 10Base-5 or 10Base-2.
Rules of application of technology 10Base-T:
1. The network of the standard 10Base-Æ can contain a maximum four concentrators.
2. Computers are connected to concentrators with help UTP (STP) cables of a category 3, 4 or 5.
3. Connection of computers to concentrators is carried out with the help коннекторов RJ-45 and cables of " direct connection ".
4. Connection of concentrators is among themselves carried out with the help of cables of " cross connection " or, at use Up-Link-портов - with the help of cables of direct connection.
5. The maximal length UTP of a segment - 100 m.
6. A maximum quantity of the computers connected to all concentrators a LAN - 1024.
7. The minimal length of a cable segment - 2.5 m.
8. The maximal general length of a network - 500 m.
Examples of application of technology 10Base-T
The elementary variant of application of technology 10Base-Æ

Fig. 5. The elementary example of application of technology 10Base-T

The elementary variant of the network constructed on technology 10Base-T - a network with one concentrator (see fig. 5). The most widespread low-power concentrators have 8 ports (I write 8 since once I saw the concentrator on 5 ports). With their help it is possible to organize a network of small office which will strongly not grow and does not require network administration. Such decision is comprehensible to territorially concentrated networks (within the limits of several adjacent premises(rooms)). Mean, that the price " for port " at multiport concentrators is lower. Therefore, if you plan to unit in a network about(near) 20-ти computers, it is more expedient to get one 24 port concentrator, than three 8-ми port.
Opportunities of technology 10Base-Æ
One of variants of vectorially limiting topological circuits a LAN with application of technology 10Base-T is represented on fig. 6. It(he) does not contain any pair units between which would be more than 4 concentrators.

Fig. 6. A variant of limiting topology with application of technology 10Base-T

The resume of rules and recommendations of standard IEEE 802.3
The maximal number of connections on a segment of a cable:
Under the standard 10Base-5 (a thick coaxial cable) 100
Under the standard 10Base-2 (a thin coaxial cable) 30
Under the standard 10Base-T (a cable with twisted pairs) 2
Under the standard 10Base-FL (an optical cable) 2
The maximal length of a cable in meters:
Under the standard 10Base-5 (a thick coaxial cable) 500
Under the standard 10Base-2 (a thin coaxial cable) 185
Under the standard 10Base-T (a cable with twisted pairs) 100
Under the standard 10Base-FL (an optical cable) Up to 2000 m (mm) up to 4000...20000 m (sm)
ﾷ A maximum quantity of computers in a network without application of special means - 1024.
ﾷ The maximal number of cable segments no more than five (for a network which are not containing bridges, switchboards or routers). Thus the quantity(amount) of segments from a coaxial cable cannot be more than three.
ﾷ A maximum quantity of concentrators or repeaters in any combination between the most distant units of a network - 4 (if among them there is even one Fiber-Optic Hub 5).
ﾷ A maximum quantity of bridges, switchboards or routers with functions of bridges between anyone in two units of a network - 7. It is the recommendation of the report of a coherent tree under standard IEEE 802.1. Thus when the way of the data passes through the bridge (switchboard), readout of concentrators and cable segments begins all over again. Most (switchboard) isolates the traffic of a local network since it(he) eliminates promotion of packages (forwarding) on the return party(side) of the bridge when the package has passed a cable segment on which there is a unit - addressee. Bridges and switchboards also distinguish the packages which have got in a collision (collision packets) and do not pass(miss) them on other cable segments. Thus collisions are eliminated within the framework of each of a LAN, connected by the bridge or the switchboard.

The conclusion

At designing networks of standards 10Base-5/2/T it is necessary to adhere to the requirements showed by standard IEEE 802.3. On the other hand, carrying out concrete projects, frequently it is not possible to do without these rules and it is necessary to be engaged in calculations of delays of distribution of signals or to consult at firms - manufacturers of the network equipment. However, if by development of a network you managed to observe all listed above requirements, the network will successfully function also the Customer will not state you any claims.

Gentlemen's set for the local computer network of office
The structure of the computer equipment used at office, is traditional and is defined(determined) by the typical problems(tasks) facing to employees. Modern business demands automation of accounting activity and the warehouse account, an extract of accounts and reception (departure) of messages in an electronic kind to suppliers and customers. For effective work of employees, rational use of the computer equipment the local computer network (LAN) also is created. As a rule, at office one server, workstations, some the network printers, one - two modem for an output(exit) in the Internet, reception and sending of e-mail, faxes and electronic payments, internal automatic telephone exchange on 16/24 is established. As Wednesday of transfer now in office a LAN not shielded twisted pair 5-th category (UTP) is mainly used.
Two approaches to creation of cable system
Connection of the computer equipment of the set described above in a network, at least on a paper, usually does not cause difficulties by virtue of logic simplicity traditionally used звездной* topology. Therefore, minimizing the expenses, many firms carry out a lining of a network forces of the experts, as a rule, not most experienced in nuances of installation of cable systems. Should because they bad experts, that is why, that it not their basic employment(occupation).
* The topology "star" assumes radial connection central and peripheral devices.
It is done(made) approximately so. In area of the geographical center of office the concentrator on necessary quantity(amount) портов* is established. From him(it) lines to workstations are laid. In some cases are not established настенные sockets, and the wire from the concentrator is directly connected to a network card(map) of a computer. On it the lining of a local network comes to an end. At the best the cable is stacked in короба, in the worse - the cable is laid along walls or fastens improvised means to a plinth and becomes " easy extraction " for legs(foots) of employees, legs of chairs and a mop of the cleaner.
* The concentrator can have 8, 16 or 24 ports.
It is necessary to note in addition some variants of the organization a LAN of office: with two concentrators established(installed) in different premises(rooms) or on different floors; interfaces of an existing network on a coaxial cable with a network on twisted pair with the purpose of escalating number of users, etc. To consider(examine) in detail these variants it is not meaningful, since they are created under one script about which we already spoke.
Telecommunication for office is not less important, than a LAN. How the lining of telephone lines is usually made? For this purpose operators who lay the communication lines are invited. And your office starts to blossom an abundance of "noodles" * on walls. With the purpose of economy telephone lines are laid only in those places where today there should be phones. More often the stage of a lining of telephone lines precedes a lining of cables of a local network. In it the original trap for the person accepting the decision on also will consist how to organize a LAN of the office. What for to be spent for the additional equipment and to structure cable system if phones already work? That it for the additional equipment, will be told below.
* "Noodles" - the slangy name of the telephone wire reminding a macaroni product.
Creating thus cable structure of the office, we do not reflect, that will be tomorrow. And the life does not cost on a place. If your business develops, the quantity(amount) of users of a network increases, besides they move from a place on a place, and before you again there are eternal questions: " With what to start? " And " What to do(make)? " And it is necessary or to do(make) about what we already spoke, or to alter all anew.
How to receive predicted result
Let's consider the rational approach and advantages which it(he) promises. The rational approach means a stage of planning of cable system of office in view of requirements and standards of structured cable networks (СКС).
At planning cable system proceed from the following reasons: on each workplace a LAN one information and one telephone socket should be established; the pair such sockets is established on everyone of 6...10 m2 of the area; active network (the concentrator or the switchboard) and passive кроссовое (patches - panels) the equipment concentrates in one place - a switching case. For reduction of length of telephone lines the internal automatic telephone exchange settles down in a case or in immediate proximity from him(it). Such approach gives a number(line) of advantages in comparison with traditional.
First, there is no necessity for a lining of telephone lines separate cables. It is done(made) by means of the same cable which is used for connection of computers in a network. The secret is very simple. Cable UTP of 5-th category contains 4 twisted pairs from which two are used for signaling a LAN, and two others are used as telephone. The economy of means is available due to reduction of quantity(amount) of a cable and cost of works on his(its) lining.
Second, at movings users inside office there is no necessity for a lining of new telephone lines since they initially are available on any workplace.
Thirdly, at addition of new users it is not necessary to lay new кабели. Using one not involved telephone socket, it is possible to connect the additional user to a network by means of the same unused pairs in a cable. If nevertheless a new cable to lay it is necessary, you simultaneously receive both a telephone and information line. The optimum decision is some redundancy of originally laid communication lines since the lining of additional lines manages twice more expensively.
For the benefit of such approach it is necessary to specify in addition and that to is again established(installed) to networks in 70 % of cases is showed the requirement of an opportunity of work of speeds 100 Mbit / with. For realization such СКС it is necessary to follow strictly to recommendations of standards, and with a lining of a cable to charge the skilled assemblers past(last) special preparation.
The technical decisions based on structurization of cable system and creating convenience at operation, - not end in itself, and need(requirement) of today. Putting today it is more, tomorrow you spend less. Life cycle of cable system in some times exceeds life cycle of the computer equipment which each one and a half - two year should be modernized. Correctly designed cable system manages more cheaply in operation, serves longer, and the main thing - is more reliable. We shall consider a role and problems(tasks) of the additional equipment mentioned by us which usually ignore with a view of economy.
 

How to choose the additional equipment

The important place in a LAN of office borrows(occupies) a switching case. Actually the case in work a LAN of direct participation does not accept, but allows to protect the active and passive equipment which in him(it) is established, from playful handles of curious employees, a dust, electromagnetic fields, change of temperature and mechanical influences. If you are disturbed seriously with safety of the information stored(kept) on a server, and you want to limit access to it(him) of extraneous persons in a locked case of the suitable size it is necessary to establish and a server. Sometimes such decision is is unique comprehensible since in small office to allocate a special server room it is not obviously possible. The internal automatic telephone exchange also is rational for placing in a case, on the same reasons. The sizes настенных and floor cases are resulted in units (in abbreviated form U), i.e. in quantity(amount) of landing places of the standard 19-inch equipment which can be established in a case. The landing place in one U borrows(occupies) on height about 45 mm. In our market cases in the size from 6 U up to 44 U are offered.
At first sight unnecessary, but rather useful detail in cable system of office the patch - panel is following. Inherently it is a 19-inch metal plate on which jacks RJ-11 or RJ-45 for connection accordingly telephone or information lines are placed. The quantity(amount) of ports (jacks) on the patch - panel is usual 12 or 24 though there are panels on 48 and even 96 ports. Information and telephone jacks from the back party(side) of the panel directly incorporate with corresponding настенными sockets by means of the laid cable. From a face sheet by means of a patch - cord (a piece of a cable in length of 1 m on which both ends are established коннекторы RJ-11 or RJ-45) to jacks are connected target lines of internal automatic telephone exchange or ports of the concentrator. Moving, for example, the telephone subscriber from one room in another is made within several seconds by switching of a patch - cord on the patch - panel from one jack in another.
For small networks about which we also speak, it is convenient to apply 24-port type-setting patches - panels in which it is possible to establish in the any order as jacks RJ-11, and RJ-45. It simplifies closing up of a cable at installation and administration at operation. In a case such panel takes a landing place 1 U. It is impossible to forget and about an opportunity of crossing(moving) of office in a new building. In this case all established components a LAN can be used after dismantle repeatedly (up to 5...7 times), and patches - panels are reorganized with reference to new conditions.
Usually, when it is made a decision on purchase of the equipment, it would be desirable to get or the most good, or inexpensive, and it is even better, if both these qualities are combined in one sample. But so it does not happen! One only list СКС which are offered by various firms, looks rather impressively. Also it happens to stop difficultly the choice on something one. Adherents of one СКС find faults with others, and on the contrary. We shall not press now in consideration of technical subtleties and distinctions of this or that СКС is a theme of separate conversation. We shall tell only, that technical decisions and characteristics of all СКС answer world(global) and European standards and any of them has the right of a registration at your office. The approach to creation a LAN which allows to avoid many troubles at operation is important. Technical details of concrete realization we shall leave to experts in the field of network integration.
Undoubtedly, that components СКС about which we spoke, from brandname are always more dear(expensive) similar nonename, made, for example, on Taiwan. It is possible to lower essentially cost of the equipment, having bought patches - panels and sockets of such origin, thus having kept the general(common) approach to construction of a network. However if you want to receive a stable network on 100 Mb / with it is better to address to certificated инсталлятору this or that СКС. If you apply components from various manufacturers even if these components have marks CAT 5 the disappointment can expect you. Besides the certificated firms give usually 15-years guarantee on components or on all cable system from supplier СКС. It is interesting to note that fact that is far from being all customers of office networks demand such guarantee.
Long-term work is of interest for any customer with one reliable supplier of the equipment and services. In the domestic market firms which will offer you in a complex everything that is necessary for the organization a LAN and successful further work work: servers, workstations, printers, modems, the license software, a lining of a cable, adjustment(option) of network OS, repair, maintenance service and modernization of the computer equipment, training of the personnel and many other things.
 

The list of the Literature

1. The engineering specifications to УАТС Coral I.
2. Olifer V.G., Olifer N.A. “ Computer networks. Principles, technologies, reports ” - Saint Petersburg, 200 - 672 with.
3. http://www.intercom.kharkov.ua/faq/modem/isdn_test.html - Vyacheslav Babitsyna's clause(article) “ Testing of equipment ISDN ”
4. http://javaworld.osp.ru/lan/1996/03/77.htm - clause(article) Фрэнка of Leeds “ Connection to ISDN ”