Modern society has entered the post-industrial era, which is characterized by the fact that information has become the most important resource for the development of the economy and society. In line with the general development of high technologies, computer technologies make the main contribution to the informatization of all spheres of life.
One of the characteristic features of the current stage of development information technologies can be defined by the words “unification” or “integration”. Analogue and digital, telephone and computer are united, speech, data, audio and video signals are united in one stream, technology and art (multimedia and hypermedia) are united in a single technology. The flip side of this process is “division” or “collective use” (sharing). An integral part of this process is the development of computer networks.
Computer networks are essentially distributed systems. The main feature of such systems is the presence of several data processing centers. Computer networks, also called computer networks or data networks, are the logical result of the evolution of two of the most important scientific and technical branches of modern civilization - computer and telecommunication technologies. On the one hand, networks are a special case of distributed computing systems in which a group of computers coordinately performs a group of interrelated tasks, exchanging data in automatic mode. On the other hand, computers and data multiplexing have developed in various telecommunication systems.
Local area network (LAN) or LAN is a group personal computers or peripheral devices interconnected by a high-speed data transmission channel in the location of one or many nearby buildings. The main task that is set when building local computer networks is the creation of a company’s telecommunications infrastructure that ensures the solution of assigned tasks with the greatest efficiency. There are a number of reasons for combining individual personal computers into a LAN:
Firstly, sharing resources allows several PCs or other devices to share access to a separate disk (file server), DVD-ROM drive, printers, plotters, scanners and other equipment, which reduces costs for each individual user.
Secondly, in addition to sharing expensive peripheral devices, LVL allows you to similarly use network versions of application software.
Thirdly, the LAN provides new forms of interaction between users in one team, for example, working on a common project.
Fourth, LANs make it possible to use common means of communication between various application systems (communication services, data and video transmission, voice, etc.).
Three principles of LAN can be distinguished:
1) Openness of connectivity additional computers and other devices, as well as communication lines (channels) without changing the hardware and software of existing network components.
2) Flexibility – maintaining operability when the structure changes as a result of the failure of any computer or communication line.
3) Efficiency providing the required quality of user service at minimal cost.
The local network has the following distinctive features:
High data transfer speed (up to 10 GB), large bandwidth;
Low transmission error rate (high quality transmission channels);
Efficient, fast data exchange control mechanism;
A precisely defined number of computers connected to the network. Currently, it is difficult to imagine any organization without a local network installed in it; all organizations strive to modernize their work with the help of local networks.
This course project describes the creation of a local network based on Gigabit Ethernet technology, by connecting several houses, and organizing access to the Internet.
Topology is a way of physically connecting computers into a local network.
There are three main topologies used when building computer networks:
Topology "Bus";
Star topology;
Ring topology.
When creating a network with the “Bus” topology, all computers are connected to one cable (Figure 1.1). Terminators should be located at its ends. 10 Megabit networks 10Base-2 and 10Base-5 are built using this topology. The cable used is Coaxial cables.
Figure 1.1 – “Bus” topology
Passive topology is based on the use of one common communication channel and its collective use in time sharing mode. Failure of a common cable or any of two terminators leads to failure of the network section between these terminators (network segment). Disabling any of the connected devices does not have any effect on the network. A communication channel failure disables the entire network. All computers on the network “listen” to the carrier and do not participate in data transfer between neighbors. The throughput of such a network decreases as the load increases or the number of nodes increases. To connect pieces of the bus, active devices - repeaters (repeaters) with an external power source can be used.
The “Star” topology involves connecting each computer with a separate wire to a separate port of a device called a hub or repeater (repeater), or hub (Hub) (Figure 1.2).
Figure 1.2 – Star topology
Concentrators can be either active or passive. If the connection between the device and the hub is lost, the rest of the network continues to work. True, if this device was the only server, then the work will be somewhat difficult. If the hub fails, the network will stop working.
This network topology is most convenient when searching for damage to network elements: cables, network adapters or connectors. When adding new devices, a star is also more convenient than a shared bus topology. You can also take into account that 100 and 1000 Mbit networks are built using the “Star” topology.
Ring topology is an active topology. All computers on the network are connected in a closed circle (Figure 1.3). Laying cables between workstations can be quite difficult and expensive if they are not arranged in a ring, but, for example, in a line. Twisted pair or optical fiber is used as media in the network. Messages circulate in circles. A workstation can transmit information to another workstation only after it has received the transmission right (token), so collisions are avoided. Information is transmitted along the ring from one workstation to another, so if one computer fails, unless special measures are taken, the entire network will fail.
Message transmission time increases in proportion to the number of nodes in the network. There are no restrictions on the diameter of the ring, because it is determined only by the distance between nodes in the network.
In addition to the above network topologies, the so-called. Hybrid topologies: star-bus, star-ring, star-star.
Figure 1.3 – “Ring” topology
In addition to the three considered basic topologies, the “tree” network topology is also often used, which can be considered as a combination of several stars. As with a star, a tree can be active, or true, and passive. With an active tree, central computers are located at the centers of combining several communication lines, and with a passive tree, there are concentrators (hubs).
Combined topologies are also used quite often, among which star-bus and star-ring topologies are the most widespread. A star-bus topology uses a combination of a bus and a passive star. In this case, both individual computers and entire bus segments are connected to the hub, that is, a physical “bus” topology is actually implemented, including all computers on the network. In this topology, several hubs can be used, interconnected and forming the so-called backbone, support bus. Separate computers or bus segments are connected to each of the hubs. Thus, the user has the opportunity to flexibly combine the advantages of bus and star topologies, as well as easily change the number of computers connected to the network.
In the case of a star-ring topology, it is not the computers themselves that are united into a ring, but special hubs, to which the computers in turn are connected using star-shaped double communication lines. In reality, all computers on the network are included in a closed ring, since inside the hubs all communication lines form a closed loop. This topology allows you to combine the advantages of star and ring topologies. For example, hubs allow you to collect all network cable connection points in one place.
This course project will use a star topology, which has the following advantages:
1. failure of one workstation does not affect the operation of the entire network as a whole;
2. good network scalability;
3. easy troubleshooting and network breaks;
4. high network performance (subject to proper design);
5. flexible administration options.
The choice of cabling subsystem is dictated by the type of network and the selected topology. The physical characteristics of the cable required by the standard are laid down during its manufacture, as evidenced by the markings applied to the cable. As a result, today almost all networks are designed on the basis of UTP and fiber-optic cables; coaxial cable is used only in exceptional cases and then, as a rule, when organizing low-speed stacks in wiring closets.
Today, only three types of cables are included in local area network projects (standard):
coaxial (two types):
Thin coaxial cable;
Thick coaxial cable.
twisted pair (two main types):
Unshielded twisted pair (UTP);
Shielded twisted pair (STP).
fiber optic cable (two types):
Multimode cable (fiber optic cable multimode);
Single-mode cable (fiber optic cable single mode).
Not long ago, coaxial cable was the most common type of cable. This is due to two reasons: firstly, it was relatively inexpensive, lightweight, flexible and easy to use; Secondly, the widespread popularity of coaxial cable has made it safe and easy to install.
The simplest coaxial cable consists of a copper core, insulation, its surrounding, a screen in the form of a metal braid and an outer sheath.
If the cable, in addition to the metal braid, also has a “foil” layer, it is called a double-shielded cable (Figure 1.4). If there is strong interference, you can use a cable with quadruple shielding; it consists of a double layer of foil and a double layer of metal braid.
Figure 1.4 – Coaxial cable structure
The braid, called a shield, protects the data transmitted along the cables by absorbing external electromagnetic signals, called interference or noise, so that the shield prevents interference from corrupting the data.
Electrical signals are transmitted along the core. A core is one wire or a bundle of wires. The core is usually made of copper. The conductive core and the metal braid must not touch, otherwise a short circuit will occur and noise will distort the data.
Coaxial cable is more noise-resistant and has less signal attenuation than twisted pair cable.
Attenuation is the decrease in the magnitude of a signal as it moves along a cable.
Thin coaxial cable is a flexible cable with a diameter of about 5 mm. It is applicable to almost any type of network. Connects directly to the network adapter board using a T-connector.
The cable connectors are called BNC connectors. A thin coaxial cable is capable of transmitting a signal over a distance of 185 m, without slow attenuation.
Thin coaxial cable belongs to a group called the RG-58 family. The main distinguishing feature of this family is the copper core.
RG 58/U – solid copper core.
RG 58/U – intertwined wires.
RG 58 C/U - military standard.
RG 59 – used for broadband transmission.
RG 62 – used in Archet networks.
Thick coaxial cable is a relatively rigid cable with a diameter of about 1 cm. It is sometimes called the Ethernet standard because this type of cable was designed for this network architecture. The copper core of this cable is thicker than that of a thin cable, so it transmits signals further. To connect to a thick cable, a special transceiver device is used.
The transceiver is equipped with a special connector called a “vampire tooth” or piercing coupler. It penetrates the insulating layer and comes into contact with the conductive core. To connect the transceiver to the network adapter, you need to connect the transceiver cable to the AUI connector - port to the network card.
Twisted pair is two insulating wires twisted around each other. copper wires. There are two types of thin cable: unshielded twisted pair (UTP) and shielded twisted pair (STP) (Figure 1.5).
Figure 1.5 – Unshielded and shielded twisted pair
Several twisted pairs are often placed in a single protective enclosure. Their number in such a cable may vary. Curling wires allows you to get rid of electrical noise induced by neighboring pairs and other sources (motors, transformers).
Unshielded twisted pair (10 Base T specification) is widely used in LAN, the maximum segment length is 100 m.
Unshielded twisted pair cable consists of 2 insulated copper wires. There are several specifications that regulate the number of turns per unit length, depending on the purpose of the cable.
1) Traditional telephone cable, which can only carry voice.
2) A cable capable of transmitting data at speeds up to 4 Mbit/s. Consists of 4 twisted pairs.
3) A cable capable of transmitting data at speeds up to 10 Mbit/s. Consists of 4 twisted pairs with 9 turns per meter.
4) A cable capable of transmitting data at speeds up to 16 Mbit/s. Consists of 4 twisted pairs.
5) A cable capable of transmitting data at speeds up to 100 Mbit/s. Consists of 4 twisted pairs of copper wire.
One potential problem with all cable types is crosstalk.
Crosstalk is crosstalk caused by signals on adjacent wires. Unshielded twisted pair cable is particularly susceptible to this interference. To reduce their influence, a screen is used.
Shielded twisted pair (STP) cable has a copper braid that provides more protection than unshielded twisted pair. Pairs of STP wires are wrapped in foil. As a result, shielded twisted pair cable has excellent insulation, protecting the transmitted data from external interference.
Therefore, STP is less susceptible to electrical interference than UTP and can transmit signals at higher speeds and over longer distances.
To connect twisted pair cables to a computer, use RG-45 telephone connectors.
Figure 1.6 – Fiber optic cable structure
In a fiber optic cable, digital data is distributed along optical fibers in the form of modulated light pulses. This is a relatively reliable (secure) method of transmission, since no electrical signals are transmitted. Therefore, a fiber optic cable cannot be hidden and data cannot be intercepted, which is not the case for any cable carrying electrical signals.
Fiber optic lines are designed to move large amounts of data at very high speeds, as the signal in them has virtually no attenuation or distortion.
An optical fiber is an extremely thin glass cylinder, called the core, covered with a layer of glass, called the cladding, with a different refractive index than the core (Figure 1.6). Sometimes optical fiber is made from plastic; it is easier to use, but has worse characteristics compared to glass.
Each glass fiber transmits signals in only one direction, so the cable consists of two fibers with separate connectors. One of them is used for signal transmission, the other for reception.
Transmission via fiber optic cable is not subject to electrical interference and is carried out at extremely high speeds (currently up to 100 Mbit/s, theoretically possible speed is 200,000 Mbit/s). It can transmit data over many kilometers.
In this course project, “Twisted pair” category 5E and “Fiber optic cable” will be used.
When organizing the interaction of nodes in local networks, the main role is given to the link layer protocol. However, in order for the link layer to cope with this task, the structure of local networks must be quite specific, for example, the most popular link layer protocol - Ethernet - is designed for parallel connection of all network nodes to a common bus for them - a piece of coaxial cable. A similar approach is to use simple structures cable connections between computers on a local network corresponded to the main goal set by the developers of the first local networks in the second half of the 70s. This goal was to find a simple and cheap solution for connecting several dozen computers located within the same building into a computer network.
This technology has lost its practicality, since now not tens, but hundreds of computers located not only in different buildings, but also in different areas are connected into local networks. Therefore, we choose a higher speed and reliability of information transmission. These requirements are met by Gigabit Ethernet 1000Base-T technology.
Gigabit Ethernet 1000Base-T, based on twisted pair and fiber optic cable. Since Gigabit Ethernet technology is compatible with 10 Mbps and 100 Mbps Ethernet, easy migration to this technology is possible without investing large amounts of money in software, cable structure and personnel training.
Gigabit Ethernet technology is an extension of IEEE 802.3 Ethernet that uses the same packet structure, format, and support for CSMA/CD, full duplex, flow control, and more, while providing a theoretical tenfold increase in performance.
CSMA/CD (Carrier-Sense Multiple Access with Collision Detection - multiple access with carrier sensing and collision detection) is a technology for multiple access to a common transmission medium in a local computer network with collision control. CSMA/CD refers to decentralized random methods. It is used both in regular Ethernet-type networks and in high-speed networks (Fast Ethernet, Gigabit Ethernet).
Also called a network protocol that uses the CSMA/CD scheme. The CSMA/CD protocol operates at the data link layer in the OSI model.
The characteristics and areas of application of these popular networks in practice are associated precisely with the characteristics of the access method used. CSMA/CD is a modification of the “pure” Carrier Sense Multiple Access (CSMA).
If, while transmitting a frame, the workstation detects another signal occupying the transmission medium, it stops the transmission, sends a jam signal, and waits for a random amount of time (known as the "backoff delay" and found using the truncated binary exponential backoff algorithm) before send the frame again.
Collision detection is used to improve CSMA performance by aborting transmission immediately after a collision is detected and reducing the likelihood of a second collision during retransmission.
Collision detection methods depend on the equipment used, but on electrical buses such as Ethernet, collisions can be detected by comparing transmitted and received information. If it differs, then another transmission overlaps the current one (a collision has occurred) and the transmission is interrupted immediately. A jam signal is sent, which causes all transmitters to delay transmission for a random amount of time, reducing the likelihood of a collision during a retry.
Choice hardware special attention must be paid; the possibility of expanding the system and the ease of its modernization play a significant role, since this is what allows us to ensure the required performance not only at the current time, but also in the future.
Of greatest interest is the maximum volume random access memory, which can be used on this server, the ability to install more powerful processor, as well as a second processor (if you plan to use an operating system that supports a dual-processor configuration). An important question also remains: what configuration disk subsystem can be used on this server, first of all, what is the volume of disks, their maximum number.
There is no doubt that a vital parameter of any server is its high-quality and uninterrupted power supply. In this regard, it is necessary to check whether the server has several (at least two) power supplies. Typically these two power supplies operate in parallel, i.e. If it fails, the server continues to operate, receiving power from another (working) power supply. At the same time, it should also be possible to “hot” replace them. And, of course, an uninterruptible power supply is required. Its presence allows, in the event of a power failure, to at least correctly shut down the operating system and turn on the server.
High reliability of servers is achieved by implementing a set of measures related to ensuring the necessary heat exchange in the case, monitoring the temperature of the most important components, monitoring a number of other parameters, and complete or partial duplication of subsystems.
It is also necessary to pay attention to the selection of additional network hardware components. When choosing network equipment, it is worth considering the network topology and the cabling system on which it is implemented.
· Level of equipment standardization and its compatibility with the most common software;
· Speed of information transfer and the possibility of its further increase;
· Possible network topologies and their combinations (bus, passive star, passive tree);
· Network exchange control method (CSMA/CD, full duplex or token method);
· Permitted types of network cable, its maximum length, immunity to interference;
· Cost and technical characteristics of specific hardware (network adapters, transceivers, repeaters, hubs, switches).
Minimum server requirements:
CPU AMD Athlon 64 X2 6000+ 3.1GHz;
Dual NC37H network adapters with TCP/IP Offload Engine network card;
RAM 8 GB;
HDD 2x500 GB Seagate Barracuda 7200 rpm.
Computer network software consists of three components:
1) stand-alone operating systems (OS) installed on workstations;
2) network operating systems installed on dedicated servers, which are the basis of any computer network;
3) network applications or network services.
As a rule, modern 32-bit operating systems are used as stand-alone operating systems for workstations - Windows 95/98, Windows 2000, Windows XP, Windows VISTA.
The following are used as network operating systems in computer networks:
NetWare OS from Novell;
Microsoft network operating systems (Windows NT, Microsoft Windows 2000 Server, Windows Server 2003, Windows Server 2008)
Windows Server 2008 provides three main benefits:
1) Improved control
Windows Server 2008 allows you to gain greater control over your server and network infrastructure so you can focus on the tasks that matter most by doing the following.
Simplified IT infrastructure management with new tools that provide a single interface for setting up and monitoring servers and the ability to automate routine operations.
Streamline the installation and management of Windows Server 2008 by deploying only the roles and features you need. Customizing server configurations reduces vulnerabilities and reduces the need for software updates, resulting in easier ongoing maintenance.
Efficiently detect and resolve problems with powerful diagnostics that provide visibility into the current health of your server environment, both physical and virtual.
Improved control over remote servers, such as branch servers. By streamlining server administration and data replication processes, you can better serve your users and eliminate some management headaches.
Easily manage your web servers with Internet Information Services 7.0, a powerful web platform for applications and services. This modular platform features a simpler task-based management interface and integrated web service state management, provides strong control over node interactions, and includes a number of security enhancements.
Improved control of user settings using advanced Group Policy.
2) Increased flexibility
The following features in Windows Server 2008 enable you to create flexible and dynamic data centers that meet your company's ever-changing needs.
Built-in technologies for virtualization of several operating systems (Windows, Linux, etc.) on one server. Thanks to these technologies, as well as simpler and more flexible licensing policies, it is now possible to easily take advantage of the economic benefits of virtualization.
Centralized application access and seamless integration of remotely published applications. In addition, it should be noted that it is possible to connect to remote applications through a firewall without using a VPN - this allows you to quickly respond to the needs of users, regardless of their location.
Wide range of new deployment options.
Flexible and powerful applications connect workers to each other and to data, thereby enabling visibility, sharing and processing of information.
Interaction with the existing environment.
A developed and active community for support throughout the life cycle.
3) Improved protection
Windows Server 2008 strengthens the security of your operating system and overall environment, creating a strong foundation on which you can grow your business. Windows Server protects servers, networks, data, and user accounts from disruption and intrusion by:
Enhanced security features reduce server core vulnerabilities, resulting in a more reliable and secure server environment.
Network Access Protection technology allows you to isolate computers that do not meet the requirements of current security policies. The ability to enforce security requirements is a powerful tool for protecting your network.
Advanced solutions for writing intelligent rules and policies that improve the manageability and security of network functions enable the creation of policy-regulated networks.
Data protection that allows access only to users with the proper security context and prevents loss in the event of hardware failure.
Defence from malware using User Account Control with a new authentication architecture.
Increased system resiliency, reducing the likelihood of loss of access, work output, time, data and control.
For users of local area networks, a set of network services is of great interest, with the help of which he can view a list of computers on the network, read a remote file, print a document on a printer installed on another computer on the network, or send an email message.
Implementation of network services is carried out by software (software). The file service and print service are provided by operating systems, and the remaining services are provided by network application programs or applications. To traditional network services include: Telnet, FTP, HTTP, SMTP, POP-3.
The Telnet service allows you to organize user connections to the server using the Telnet protocol.
The FTP service allows you to transfer files from Web servers. This service is provided by Web browsers (Internet Explorer, Mozilla Firefox, Opera, etc.)
HTTP is a service designed for viewing Web pages (Web sites), provided by network application programs: Internet Explorer, Mozilla Firefox, Opera, etc.
SMTP, POP-3 - incoming and outgoing email services. Implemented by email applications: Outlook Express, The Bat, etc.
An anti-virus program is also required on the server. ESET NOD32 Smart Security Business Edition is a new integrated solution that provides comprehensive protection for servers and workstations for all types of organizations.
This solution includes antispam and personal firewall functions that can be used directly on the workstation.
ESET NOD32 Smart Security Business Edition provides support for file Windows servers, Novell Netware and Linux/FreeBSD and their protection against known and unknown viruses, worms, Trojan horses and spyware, as well as other Internet threats. The solution has the ability to scan on access, on demand and automatically update.
ESET NOD32 Smart Security Business Edition includes ESET Remote Administrator, providing updates and centralized administration in corporate network environments or wide area networks. The solution ensures optimal system and network performance while reducing power consumption bandwidth. The solution has the functionality and flexibility that any company needs:
1) Installation on the server. The corporate version of ESET NOD32 Smart Security can be installed on both servers and workstations. This is especially important for companies seeking to maintain their competitive edge, since servers are just as vulnerable to attack as regular workstations. If the servers are not protected, one virus can damage the entire system.
2) Remote administration. With ESET Remote Administrator, you can monitor and administer your security software solution from anywhere in the world. This factor is of particular importance for companies distributed geographically, as well as for system administrators who prefer remote work or travel.
Possibility of "Mirrors". ESET NOD32's mirror feature allows the IT administrator to limit network bandwidth by creating an internal update server. As a result, ordinary users do not need to go online to receive updates, which not only saves resources, but also reduces the overall vulnerability of the information structure.
1.6 Brief network plan
Table 1.1 – Brief summary of equipment
The following equipment will be used in this course project:
Switch D-link DGS-3200-16;
Switch D-link DGS-3100-24;
Router D-link DFL-1600;
Converter 1000 Mbit/s D-Link DMC-810SC;
IBM System x3400 M2 7837PBQ server.
Figure 2.1 – D-link DGS-3200-16 switch
General characteristics
Device type switch
There is
Number of slots for additional
interfaces 2
Control
Console port There is
Web interface There is
Telnet support There is
SNMP support There is
Additionally
IPv6 support There is
Standards support Auto MDI/MDIX, Jumbo Frame, IEEE 802.1p (Priority tags), IEEE 802.1q (VLAN), IEEE 802.1d (Spanning Tree), IEEE 802.1s (Multiple Spanning Tree)
Dimensions (WxHxD) 280 x 43 x 180 mm
Number of ports 16 x Ethernet 10/100/1000
switch Mbit/sec
32 Gbit/s
MAC address table size 8192
Router
IGMP v1
Figure 2.2 – D-link DGS-3100-24 switch
General characteristics
Device type switch
Rack mountable There is
Number of slots for additional interfaces 4
Control
Console port There is
Web interface There is
Telnet support There is
SNMP support There is
Additionally
Standards support Auto MDI/MDIX, Jumbo Frame, IEEE 802.1p (Priority tags), IEEE 802.1q (VLAN), IEEE 802.1d (Spanning Tree), IEEE 802.1s (Multiple Spanning Tree)
Dimensions (WxHxD) 440 x 44 x 210 mm
Weight 3.04 kg
Additional Information 4 1000BASE-T/SFP combo ports
Number of ports 24 x Ethernet 10/100/1000
switch Mbit/sec
Stack support There is
Internal Bandwidth 68 Gbit/s
MAC address table size 8192
Router
Dynamic routing protocols IGMP v1
Figure 2.3 – D-link DFL-1600 router
General characteristics
Device type router
Control
Console port There is
Web interface There is
Telnet support There is
SNMP support There is
Additionally
Standards support IEEE 802.1q (VLAN)
Dimensions (WxHxD) 440 x 44 x 254 mm
Additional Information 6 user configurable Gigabit Ethernet ports
Number of ports 5 x Ethernet 10/100/1000
switch Mbit/sec
Router
Firewall There is
NAT There is
DHCP server There is
Dynamic protocols
routing IGMP v1, IGMP v2, IGMP v3, OSPF
VPN tunnel support yes (1200 tunnels)
Figure 2.4 - 1000 Mbit/s D-Link DMC-805G converter
General characteristics
· One channel for converting the transmission medium between 1000BASE-T and 1000BASE-SX/LX (SFP mini GBIC transceiver);
· Compatible with IEEE 802.3ab 1000BASE-T, IEEE802.3z 1000BASE-SX/LX Gigabit Ethernet standards;
· Status indicators on the front panel;
· Support LLCF (Link Loss Carry Forward, Link Pass Through);
· Supports duplex mode and auto-negotiation for the optical port;
· DIP switch for setting Fiber (auto/manual), LLR (Enable/Disable);
· LLR (Link Loss Return) support for FX port;
· Use as a separate device or installation in the DMC-1000 chassis;
· Duplex/link status monitoring for both media types via the DMC-1002 control module when installed in a DMC-1000 chassis;
· Forced setting of duplex mode, LLR on/off for FX, on/off ports through the DMC-1002 control module of the DMC-1000 chassis;
· Data transmission at channel speed;
· Hot swap when installed in a chassis;
Dimensions 120 x 88 x 25 mm
Weight 305
Working temperature 0° to 40° C
Storage temperature -25° to 75° C
Humidity From 10% to 95 without condensation
Figure 2.5 - IBM System x3400 M2 7837PBQ Server
Server characteristics
CPU Intel Xeon Quad-Core
Series E5520
Processor frequency A 2260 MHz
Number of processors 1 (+1 optional)
System bus frequency 1066 MHz
Level 2 cache (L2C) 8 Mb
Chipset Intel 5500
RAM capacity 12 Gb
Maximum RAM 96 Gb
RAM slots 12
RAM type DDR3
Chipset video Built-in
Video memory size 146 Mb
Number of hard drives 3
Hard drive size 0 Gb
Maximum number of disks 8
Hard Drive Controller M5015
Optical drives DVD±RW
Network interface 2x Gigabit Ethernet
External I/O ports 8xUSB ports (six external, two internal), dual-port
Installation type Tower
Power supply type 920 (x2) W
Maximum amount
power supplies 2
Dimensions 100 x 580 x 380 mm
Weight 33 kg
Guarantee 3 years
Additional Information Keyboard + Mouse
Additional components (ordered separately) IBM System x3400 M2 7837PBQ Servers
Passive equipment makes up the physical infrastructure of networks (patch panels, sockets, racks, mounting cabinets, cables, cable ducts, trays, etc.). The throughput and quality of communication channels largely depend on the quality of the cable system; therefore, to test physical storage media, complex and expensive equipment must be used under the control of qualified personnel in this field.
In the course project it is necessary to connect 4 houses. Because given floors 5th, 12th and 14th, then it is more expedient to run the main fiber optic cable through overhead communications.
To suspend the main line between poles and buildings, a special self-supporting fiber optic cable is used, which has a central power element (CSE) and a steel cable. The optimal distance between cable fastening supports is from 70 to 150 meters.
Figure 2.5 – Location of houses
Table 2.1 – Calculation of the length of the fiber optic cable of the main trunk
| Cable section | Length, m | Number of segments | Length with reserve, m |
| 1-2 | 105 | 1 | 136,5 |
| 2-3 | 75 | 1 | 97,5 |
| 3-4 | 190 | 1 | 247 |
| 4-5 | 100 | 1 | 130 |
| 5-6 | 75 | 1 | 97,5 |
| Total | 708,5 | ||
Cable risers are used to lay cables across floors. In the hallways. There is no need to pack the cable in the entrances, because... the entrances are not so dirty and the threats of sudden temperature changes and pollution are minimal.
The twisted pair from the switch on the roof to the desired floor goes along the riser without any protection, from the electrical panel to the apartment, both in cable channels and without them, simply attached to the wall with staples.
The server and router are located in building No. 2 on the 5th floor of the 3rd entrance in a sealed room with a constant temperature maintained at no more than 30o C.
Table 2.2 - Calculation of the length of twisted pair in houses
| Distance from the commutator to the hole in |
Qty of cable per apartment, m |
Length with reserve, m | ||||||||||
| 2 | 52 | 55 | 58 | 63 | 56 | 51 | 48 | 15 | 4 | 7 | 1952 | 2537,6 |
| 5 | 34 | 30 | 38 | 28 | 26 | - | - | 15 | 4 | 5 | 924 | 1201,2 |
| 7 | 42 | 45 | 48 | 53 | 46 | 41 | 38 | 15 | 4 | 7 | 1672 | 2173,6 |
| 8 | 34 | 30 | 38 | 28 | 26 | - | - | 15 | 5 | 5 | 1155 | 1501,5 |
| 5703 | 7413,9 | |||||||||||
When the switch operates, the data transmission medium of each logical segment remains common only to those computers that are directly connected to this segment. The switch communicates data transmission media of different logical segments. It transmits frames between logical segments only when necessary, that is, only when the communicating computers are in different segments.
Dividing the network into logical segments improves network performance if the network contains groups of computers that primarily exchange information with each other. If there are no such groups, then introducing switches into the network can only worsen the overall performance of the network, since deciding whether to transfer a packet from one segment to another requires additional time.
However, even in a medium-sized network, such groups usually exist. Therefore, dividing it into logical segments gives a performance gain - traffic is localized within groups, and the load on their shared cabling systems is significantly reduced.
Switches make a decision about which port to transmit a frame to by analyzing the destination address placed in the frame, as well as based on information about whether a particular computer belongs to a specific segment connected to one of the switch ports, that is, based on information about the network configuration . In order to collect and process information about the configuration of segments connected to it, the switch must go through the “training” stage, that is, it must independently do some preliminary work to study the traffic passing through it. Determining whether computers belong to segments is possible due to the presence in the frame of not only the destination address, but also the address of the source that generated the packet. Using the source address information, the switch establishes a mapping between port numbers and computer addresses. In the process of learning the network, the bridge/switch simply transmits frames appearing at the inputs of its ports to all other ports, working as a repeater for some time. After the bridge/switch learns that addresses belong to segments, it begins to transmit frames between ports only in the case of intersegment transmission. If, after completion of training, a frame with an unknown destination address suddenly appears at the switch input, then this frame will be repeated on all ports.
Bridges/switches operating in the described way are usually called transparent, since the appearance of such bridges/switches in the network is completely invisible to its end nodes. This allows them to avoid having to change their software when moving from simple hub-only configurations to more complex, segmented ones.
There is another class of bridges/switches that transmit frames between segments based on complete information about the intersegment route. This information is recorded in the frame by the frame's source station, so such devices are said to implement a source routing algorithm. When using bridges/switches with source routing, end nodes must be aware of the division of the network into segments and network adapters, in this case they must have a component in their software that selects the frame route.
The simplicity of the operating principle of a transparent bridge/switch comes at the cost of restrictions on the topology of a network built using devices of this type - such networks cannot have closed routes - loops. The bridge/switch cannot operate properly in a looped network, causing the network to become clogged with looping packets and performance degraded.
For automatic recognition loops in the network configuration, a spanning tree algorithm (STA) has been developed. This algorithm allows bridges/switches to adaptively build a link tree as they learn the link topology of segments using special test frames. When closed loops are detected, some links are declared redundant. A bridge/switch can only use a backup link if one of the primary links fails. As a result, networks built on the basis of bridges/switches that support the spanning tree algorithm have some margin of reliability, but it is impossible to improve performance by using multiple parallel connections in such networks.
There are 5 classes of IP addresses - A, B, C, D, E. Whether an IP address belongs to one class or another is determined by the value of the first octet (W). The correspondence between the values of the first octet and the address classes is shown below.
Table 2.3 – Octet range of IP address classes
IP addresses of the first three classes are intended for addressing individual nodes and individual networks. Such addresses consist of two parts - the network number and the node number. This scheme is similar to the postal code scheme - the first three digits encode the region, and the remaining post office within the region.
The advantages of a two-level scheme are obvious: it allows, firstly, to address entirely separate networks within a composite network, which is necessary to ensure routing, and secondly, to assign numbers to nodes within one network, regardless of other networks. Naturally, computers belonging to the same network must have IP addresses with the same network number.
IP addresses of different classes differ in the bit depth of the network and host numbers, which determines their possible range of values. The following table shows the main characteristics of Class A, B and C IP addresses.
Table 2.4 - Characteristics of IP addresses of classes A, B and C
For example, the IP address 213.128.193.154 is a Class C address and belongs to host number 154 located on network 213.128.193.0.
The addressing scheme, defined by classes A, B, and C, allows data to be sent either to a single node or to all computers on a separate network (broadcast). However, there is networking software that needs to distribute data to a specific group of nodes, not necessarily on the same network. In order for programs of this kind to function successfully, the addressing system must provide so-called group addresses. Class D IP addresses are used for these purposes. The class E address range is reserved and is not currently used.
Along with the traditional decimal form of recording IP addresses, the binary form can also be used, directly reflecting the way the address is represented in computer memory. Since an IP address is 4 bytes long, in binary form it is represented as a 32-bit binary number (that is, a sequence of 32 ones and zeroes). For example, the address 213.128.193.154 in binary form is 11010101 1000000 11000001 10011010.
The IP protocol assumes the presence of addresses that are interpreted in a special way. These include the following:
1) Addresses whose first octet value is 127. Packets sent to such an address are not actually transmitted to the network, but are processed by the software of the sending node. In this way, the node can forward the data to itself. This approach is very convenient for testing network software in environments where there is no network connection.
2) Address 255.255.255.255. A packet whose destination contains the address 255.255.255.255 must be sent to all nodes of the network in which the source is located. This type of distribution is called limited broadcasting. In binary form, this address is 11111111 11111111 11111111 11111111.
3) Address 0.0.0.0. It is used for official purposes and is interpreted as the address of the node that generated the packet. The binary representation of this address is 00000000 00000000 00000000 00000000
Additionally, addresses are interpreted in a special way:
The scheme for dividing an IP address into a network number and a node number, based on the concept of an address class, is quite crude, since it assumes only 3 options (classes A, B and C) for distributing address bits to the corresponding numbers. Let's consider the following situation as an example. Let's say that a company connecting to the Internet has only 10 computers. Since class C networks are the minimum possible number of nodes, this company would have to receive a range of 254 addresses (one class C network) from the organization that distributes IP addresses. The inconvenience of this approach is obvious: 244 addresses will remain unused, since they cannot be distributed to computers of other organizations located on other physical networks. If the organization in question had 20 computers distributed over two physical networks, then it would have to be allocated the range of two Class C networks (one for each physical network). In this case, the number of “dead” addresses will double.
For a more flexible definition of the boundaries between the bits of network and host numbers within an IP address, so-called subnet masks are used. A subnet mask is a special type of 4-byte number that is used in conjunction with an IP address. The “special type” of a subnet mask is as follows: the binary bits of the mask corresponding to the bits of the IP address allocated for the network number contain ones, and the bits corresponding to the bits of the host number contain zeros.
Using a subnet mask in conjunction with an IP address allows you to abandon the use of address classes and make the entire IP addressing system more flexible.
For example, the mask 255.255.255.240 (11111111 11111111 11111111 11110000) allows you to split a range of 254 IP addresses belonging to one class C network into 14 ranges that can be allocated to different networks.
For the standard division of IP addresses into network number and host number, defined by classes A, B and C, subnet masks have the form:
Table 2.5 – Subnet masks of classes A, B and C
|
Class |
Binary form |
Decimal form |
| 11111111 00000000 00000000 00000000 | 255.0.0.0 | |
| 11111111 11111111 00000000 00000000 | 255.255.0.0 | |
| 11111111 11111111 11111111 00000000 | 255.255.255.0 |
Since each Internet node must have a unique IP address, the task of coordinating the distribution of addresses to individual networks and nodes is, of course, important. This coordinating role is performed by the Internet Corporation for Assigned Names and Numbers (ICANN).
Naturally, ICANN does not solve the problem of allocating IP addresses to end users and organizations, but rather distributes address ranges between large Internet Service Provider organizations, which, in turn, can interact with smaller providers and with end users. For example, ICANN delegated the functions of distributing IP addresses in Europe to the RIPE Coordination Center (RIPE NCC, The RIPE Network Coordination Centre, RIPE - Reseaux IP Europeens). In turn, this center delegates some of its functions to regional organizations. In particular, Russian users are served by the Regional Network Information Center "RU-CENTER".
In this network, IP addresses are distributed using the DHCP protocol.
The DHCP protocol provides three ways to distribute IP addresses:
1) Manual distribution. In this method, the network administrator maps the hardware address (usually the MAC address) of each client computer to a specific IP address. In fact, this method of distributing addresses differs from manually configuring each computer only in that information about addresses is stored centrally (on DHCP server), and therefore easier to change if necessary.
2) Automatic distribution. With this method, each computer is allocated an arbitrary free IP address from a range defined by the administrator for permanent use.
3) Dynamic distribution. This method is similar to automatic distribution, except that the address is issued to the computer not for permanent use, but for a certain period. This is called renting an address. After the lease period expires, the IP address is again considered free, and the client is required to request a new one (it may, however, be the same).
The IP addresses in the course project are class B and have a mask of 225.225.0.0. Issued by the DHCP protocol with binding to the MAC address to avoid illegal connections.
Table 2.6 - Purpose of subnets
| House number | Number of entrances | Floor number | Subnet address |
| 2 | 4 | 5 | |
| 5 | 4 | 4 | |
| 7 | 4 | 10 | |
| 8 | 5 | 11 |
Two-way satellite Internet involves receiving data from a satellite and sending it back also via satellite. This method is of very high quality, as it allows you to achieve high speeds when transmitting and sending, but it is quite expensive and requires obtaining permission for radio transmitting equipment (however, the latter is often taken care of by the provider).
One-way satellite Internet requires the user to have some existing method of connecting to the Internet. As a rule, this is a slow and/or expensive channel (GPRS/EDGE, ADSL connection where Internet access services are poorly developed and limited in speed, etc.). Only requests to the Internet are transmitted through this channel. These requests arrive at the one-way satellite access operator’s node (various VPN connection or traffic proxy technologies are used), and the data received in response to these requests is transmitted to the user via a broadband satellite channel. Since most users primarily get their data from the Internet, this technology allows for faster and cheaper traffic than slow and expensive landline connections. The volume of outgoing traffic over a terrestrial channel (and therefore the costs for it) becomes quite modest (the outgoing/incoming ratio is approximately 1/10 when surfing the web, from 1/100 or better when downloading files).
Naturally, using one-way satellite Internet makes sense when the available terrestrial channels are too expensive and/or slow. If you have inexpensive and fast “terrestrial” Internet, satellite Internet makes sense as a backup connection option in case the “terrestrial” one is lost or works poorly.
The core of the satellite Internet. Processes data received from the satellite and extracts useful information. There are many different types of cards, but the best known are the SkyStar family of cards. The main difference between DVB cards today is the maximum data flow rate. The characteristics also include the possibility of hardware signal decoding and software support for the product.
There are two types of satellite antennas:
· offset;
· direct focus.
Direct focus antennas are a “saucer” with a cross section in the form of a circle; the receiver is located directly opposite its center. They are more difficult to set up than offset ones and require elevation to the satellite angle, which is why they can “collect” precipitation. Offset antennas, due to shifting the focus of the “dish” (the point of maximum signal), are installed almost vertically, and therefore are easier to maintain. The antenna diameter is selected in accordance with weather conditions and the signal level of the required satellite.
The converter acts as a primary converter that converts the microwave signal from the satellite into an intermediate frequency signal. Currently, most converters are adapted to long-term exposure to moisture and UV rays. When choosing a converter, you should mainly pay attention to the noise figure. For normal operation, you should choose converters with a value of this parameter in the range of 0.25 - 0.30 dB.
To implement the two-way method, a transmitting card and a transmitting converter are added to the required equipment.
There are two complementary approaches to implementing software for satellite Internet.
In the first case, the DVB card is used as a standard network device(but only work for reception), and a VPN tunnel is used for transmission (many providers use PPTP (“Windows VPN”), or OpenVPN at the client’s choice, in some cases an IPIP tunnel is used), there are other options. In this case, packet header control is disabled in the system. The request packet goes to the tunnel interface, and the response comes from the satellite (if header control is not disabled, the system will consider the packet to be erroneous (not so in the case of Windows)). This approach allows you to use any application, but has a high latency. Most satellite providers available in the CIS (SpaceGate (Itelsat), PlanetSky, Raduga-Internet, SpectrumSat) support this method.
The second option (sometimes used in conjunction with the first): the use of special client software, which, due to knowledge of the protocol structure, allows you to speed up the receipt of data (for example, a web page is requested, the provider’s server views it and immediately, without waiting for the request, sends pictures from this pages, assuming that the client will request them anyway; the client part caches such responses and returns them immediately). Such client-side software usually works as HTTP and Socks proxies. Examples: Globax (SpaceGate + others on request), TelliNet (PlanetSky), Sprint (Raduga), Slonax (SatGate).
In both cases, it is possible to “share” traffic over the network (in the first case, sometimes you can even have several different subscriptions satellite provider and share the plate due to the special configuration of the machine with the plate (requires Linux or FreeBSD, for Windows requires third-party software)).
Some providers (SkyDSL) are required to use their own software (performing the role of both a tunnel and a proxy), which often also performs client shaping and does not allow satellite Internet to be shared between users (also does not allow the use of anything other than Windows as an OS) .
The following advantages of satellite Internet can be highlighted:
· cost of traffic during the hours of least capacity utilization
· independence from landline communication lines (when using GPRS or WiFi as a request channel)
high final speed (reception)
· ability to watch satellite TV and “fishing from satellite”
· possibility of free choice of provider
Flaws:
· the need to purchase special equipment
· complexity of installation and configuration
· generally lower reliability compared to a terrestrial connection (more components required for uninterrupted operation)
· presence of restrictions (direct visibility of the satellite) on antenna installation
· high ping (delay between sending a request and receiving a response). In some situations this is critical. For example, when working in interactive mode Secure Shell and X11, as well as in many multi-user online systems (the same SecondLife cannot work via satellite at all, the shooter Counter Strike, Call of Duty - works with problems, etc.)
· in the presence of at least pseudo-unlimited tariff plans(like “2000 rubles for 40 Gb at 512 kbit/s further - unlimited but 32 kbit/s” - TP Aktiv-Mega, ErTelecom, Omsk) terrestrial Internet is already becoming cheaper. With the further development of cable infrastructure, the cost of terrestrial traffic will tend to zero, while the cost of satellite traffic is strictly limited by the cost of launching a satellite and there are no plans to reduce it.
· when working through some operators, you will have a non-Russian IP address (SpaceGate is Ukrainian, PlanetSky is Cypriot, SkyDSL is German) as a result of which services that are used for some purposes (for example, we only allow access from the Russian Federation) determine the user’s country, will not work correctly.
· the software part is not always “Plug and Play”; in some (rare) situations there may be difficulties and it all depends on the quality of the operator’s technical support.
The course project will use two-way satellite Internet. This will allow achieving high data transfer rates and high-quality packet transmission, but will increase the costs of project implementation.
3. Safety when working at height
Work at height is considered to be all work that is performed at a height of 1.5 to 5 m from the surface of the ground, ceiling or working floor, on which work is carried out from installation devices or directly from structural elements, equipment, machines and mechanisms during their operation, installation and repair.
Persons who have reached the age of 18, have a medical certificate confirming permission to work at height, have completed training and safety instructions, and have received permission to work independently are allowed to work at height.
Work at height must be carried out using scaffolding means (scaffolding, scaffolding, decking, platforms, telescopic towers, hanging cradles with winches, ladders and other similar auxiliary devices and devices) that provide safe working conditions.
All scaffolding equipment used to organize workplaces at height must be registered, have inventory numbers and plates indicating the date of the tests performed and the next ones.
Installation of flooring and work on random supports (boxes, barrels, etc.) is prohibited.
Monitoring the condition of the scaffolding means must be carried out by persons from among the engineering and technical personnel, who are appointed by order of the enterprise (oil depot).
To perform even short-term work at height from ladders, workers of all specialties must be provided with safety belts and, if necessary, safety helmets.
Safety belts issued to workers must have test tags.
It is prohibited to use a faulty safety belt or one with an expired test period.
Work at height is carried out during the daytime.
In emergency cases (when troubleshooting), on the basis of an order from the administration, work at height at night is permitted in compliance with all safety rules under the control of engineers. At night, the work area should be well lit.
In winter, when working outdoors, scaffolding must be systematically cleared of snow and ice and sprinkled with sand.
When the wind force is 6 points (10-12 m/sec) or more, during a thunderstorm, heavy snowfall, or icy conditions, work at height in the open air is not permitted.
You cannot unauthorizedly rebuild decking, scaffolding and fences.
Electrical wires located closer than 5 m from stairs (scaffolds) must be fenced or de-energized while the work is being performed.
Workers are required to perform the assigned work, observing the labor protection requirements set out in these instructions.
For violation of the requirements of the instructions related to the work they perform, workers are responsible in the manner established by the Internal Regulations.
Simultaneous work in 2 or more tiers vertically is prohibited.
Do not place the tool at the edge of the platform or throw it and materials on the floor or the ground. The tool must be stored in a special bag or box.
It is prohibited to throw any objects to be given to the person working above. Feeding should be done using ropes, to the middle of which the necessary objects are tied. The second end of the rope should be in the hands of the worker standing below, who keeps the objects being lifted from swinging.
Anyone working at height must ensure that there are no people below his workplace.
When using ladders and stepladders, it is prohibited:
· work on and walk on unsupported structures, as well as climb over fences;
· work on the top two steps of the stairs;
· have two workers on a ladder or on one side of a stepladder;
· move up stairs with a load or with a tool in hand;
· use stairs with steps sewn with nails;
· work on faulty stairs or on steps doused with slippery petroleum products;
· increase the length of stairs, regardless of the material from which they are made;
· stand or work under stairs;
· install ladders near rotating shafts, pulleys, etc.;
· Perform work using pneumatic tools;
· Perform electric welding work.
4. Economic costs of building a local network
This course project involves the following economic costs.
Table 4.1 – List of economic costs*
| Name | Units | Qty |
per unit (rub.) |
Amount (RUB) |
| Fiber optic cable EKB-DPO 12 | m | 708,5 | 36 | 25506 |
| FTP cable 4 pairs cat.5e<бухта 305м>Exalan+ - | bay | 25 | 5890 | 147250 |
| Switch D-Link DGS-3200-16 | PC | 2 | 13676 | 27352 |
| Switch D-Link DGS-3100-24 | PC | 5 | 18842 | 94210 |
| Router D-link DFL-1600 | PC | 1 | 71511 | 71511 |
| IBM System x3400 M2 7837PBQ Server | PC | 1 | 101972 | 101972 |
| UPS APC SUA2200I Smart-UPS 2200 230V | PC | 2 | 29025 | 58050 |
| RJ-45 connectors | Pack(100pcs) | 3 | 170 | 510 |
| MT-RJ connectors | PC | 16 | 280 | 4480 |
| Server cabinet | PC | 1 | 2100 | 2100 |
| Router cabinet | PC | 1 | 1200 | 1200 |
| Switch cabinet | PC | 7 | 1200 | 8400 |
| D-Link DMC-805G converter | PC | 16 | 2070 | 33120 |
| Satellite dish + DVB card + converter | PC | 1 | 19300 | 19300 |
| Staples 6mm | Pack (50 pcs) | 56 | 4 | 224 |
| Total | 595185 | |||
Economic costs do not include the cost of installation work. Cables and connectors are designed with a margin of ~30%. Prices are indicated at the time of creation of the course project, including VAT.
In the process of developing the course project, a LAN of a residential area was created with access to the global network. An informed choice of network type was made based on consideration of multiple options. The expansion of the network is envisaged for its further growth.
During the course design, class B IP addresses were used, since there are one hundred and one workstations on the network. Address assignment was carried out using the DHCP protocol. The entrance number served as the subnet address.
In the paragraph for calculating the required amount of equipment, data and calculations of the equipment used are provided. The development cost is 611,481 rubles. All calculated parameters meet the network performance criteria.
A brief network plan has been drawn up, which indicates all the characteristics of the equipment used. The section “Safety when working with power tools” discusses the rules for handling power tools and safety precautions when working with them.
In general, the course project contains all the necessary data for building a local computer network.
1. http://www.dlink.ru;
2. http://market.yandex.ru;
3. http://www.ru.wikipedia.org.
4. Computer networks. Training course [Text] / Microsoft Corporation. Per. from English – M.: “Russian Edition” LLP “Channel Trading Ltd.”, 1998. – 696 p.
5. Maksimov, N.V. Computer networks: Textbook [Text] / N.V. Maksimov, I.I. Popov – M.: FORUM: INFRA-M, 2005. – 336 p.
The purpose of the analytical part is to consider the existing state of the subject area, characteristics of the object, telecommunication system and substantiate proposals for eliminating identified deficiencies and new technologies.
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Large companies have in circulation a large amount of data of a different nature:
It is important for management that all information is in a convenient format, easily converted and transmitted on any medium. the right hands. But paper documents have long begun to be replaced by digitized ones, since a computer can contain a lot of data, which is much more convenient to work with through process automation. This is also facilitated by the movement of information, reports and contracts to partners or inspection companies without long journeys.
Thus, the need arose to universally supply departments of companies with electronic computing devices. At the same time, the question arose about connecting these devices into a single complex for protection, safety and ease of moving files.
In this article we will tell you how to make it easier to design a local area (computer) network in an enterprise.
This is a connecting connection of a number of computers into one closed space. This method is often used in large companies and in production. You can also create a small connection of 2 – 3 devices yourself, even at home. The more inclusions there are in a structure, the more complex it becomes.
There are two types of connection, they differ in complexity and the presence of a leading, central link:
Equivalent, or peer-to-peer, are characterized by similarity in technical specifications. They have the same distribution of functions - each user can gain access to all common documents and perform the same operations. This scheme is easy to manage and does not require multiple efforts to create it. The downside is its limitation - no more than 10 members can join this circle, otherwise the overall efficiency and speed are disrupted.
Server-side design of a company's local network is more labor-intensive, however, such a system has a higher level of information security, and there is also a clear distribution of responsibilities within the web. The computer with the best technical characteristics (powerful, reliable, with more RAM) is designated as the server. This is the center of the entire LAN, all data is stored here, and from this point you can open or deny access to documents to other users.
The main properties that need to be taken into account when drawing up a project:
From the properties come the conditions that need to be taken into account when drawing up a project. The entire design process begins with the preparation of technical specifications (TOR). It contains:
When the technical specifications are compiled in accordance with the needs of users, the type of inclusion of all points in one network is selected.
These are ways to physically connect devices. The most frequent ones are represented by three figures:
During assembly, one leading cable is used, from which wires go to user computers. The main cord is directly connected to the server, which stores information. It also selects and filters data, grants or restricts access.
Advantages:
Flaws:
All user computers are connected in series - from one device to another. This is often done in the case of peer-to-peer LANs. In general, this technology is used less and less.
Advantages:
Flaws:
This is the parallel connection of devices to a network to a common source - a server. A hub or concentrator is most often used as a center. All data is transmitted through it. In this way, not only computers, but also printers, faxes and other equipment can operate. In modern enterprises, this is the most frequently used method of organizing activities.
Advantages:
Flaws:
This is a multi-stage process that requires the competent participation of many specialists, since the required cable capacity must first be calculated, the configuration of the premises taken into account, and the equipment installed and configured.
The offices of employees and management should be located in accordance with the selected topology. If the star shape suits you, then you should place the main equipment in the room that is the main one and is located in the center. This could be the management office. In the case of bus distribution, the service may be located in the room furthest along the corridor.
The drawing can be made in specialized computer-aided design programs. The products of the ZVSOFT company are ideal - they contain all the basic elements that will be required during construction.
The grid must take into account:
The characteristics of the LAN must be selected in accordance with the layout of the organization's premises and the equipment used.
When selecting and purchasing mesh elements, it is important to consider the following factors:
When drawing up a project, it is important to take into account a large number of nuances. Software from ZWSOFT will help with this. The company develops and sells multifunctional software to automate the work of design engineers. Basic CAD is an analogue of the popular but expensive package from Autodesk - AutoCAD, but surpasses it in ease and convenience of licensing, as well as in a more loyal pricing policy.
Benefits of the program:
For ZWCAD - a module that expands the functions of basic CAD in the field of designing multimedia circuits. All drawings are made with automated calculation of local area network cables and their markings.
Advantages:
It will help you make a project in three-dimensional form, create it in 3D. Intelligent tools allow you to quickly lay LAN routes to connection points, visually represent the locations of cables, organize intersections of lines, make sections of connected equipment and technological furniture (including dynamic mode). Using the component editor, you can create a library of cabinets, switching devices, cables, clamps, etc., as well as assign characteristics to them, on the basis of which you can later create specifications and cost estimates. Thus, the functions of this software will help to complete the master plan of the organization’s premises with tracing of all LAN lines.
Create a local computer network project in your enterprise together with programs from ZVSOFT.
Moscow State Mining University
Department Automated Systems Management
Course project
in the discipline "Computer networks and telecommunications"
on the topic: “Design of a local area network”
Completed:
Art. gr. AS-1-06
Yuryeva Ya.G.
Checked:
Prof., Doctor of Technical Sciences Shek V.M.
Introduction
1 Design task
2 Description of the local area network
3 Network topology
4 Local network diagram
5 OSI reference model
6 Justification for choosing a local network deployment technology
7 Network protocols
8 Hardware and software
9 Calculation of network characteristics
Bibliography
A local area network (LAN) is a communications system that connects computers and peripheral equipment in a limited area, usually no more than several buildings or one enterprise. Currently, a LAN has become an integral attribute in any computing systems with more than 1 computer.
The main advantages provided by a local network are the ability to collaborate and quickly exchange data, centralized data storage, shared access to shared resources such as printers, Internet network and others.
Another important function of a local network is the creation of fault-tolerant systems that continue to function (albeit not fully) if some of their elements fail. In a LAN, fault tolerance is ensured through redundancy and duplication; as well as flexibility in the operation of individual parts (computers) included in the network.
The ultimate goal of creating a local network in an enterprise or organization is to increase operational efficiency computing system generally.
Building a reliable LAN that meets your performance requirements and has the lowest cost requires starting with a plan. In the plan, the network is divided into segments, and a suitable topology and hardware are selected.
The bus topology is often called a linear bus. This topology is one of the simplest and most widespread topologies. It uses a single cable, called a backbone or segment, along which all computers on the network are connected.
In a network with a “bus” topology (Fig. 1.), computers address data to a specific computer, transmitting it over a cable in the form of electrical signals.
Fig.1. Bus topology
Data in the form of electrical signals is transmitted to all computers on the network; however, only the one whose address matches the recipient address encrypted in these signals receives information. Moreover, at any given time, only one computer can transmit.
Since data is transmitted to the network by only one computer, its performance depends on the number of computers connected to the bus. The more there are, i.e. The more computers waiting to transfer data, the slower the network.
However, it is impossible to derive a direct relationship between network bandwidth and the number of computers in it. Since, in addition to the number of computers, network performance is influenced by many factors, including:
· hardware characteristics of computers on the network;
· the frequency with which computers transmit data;
· type of running network applications;
· type of network cable;
· distance between computers on the network.
The bus is a passive topology. This means that computers only “listen” to data transmitted over the network, but do not move it from sender to recipient. Therefore, if one of the computers fails, it will not affect the operation of the others. In active topologies, computers regenerate signals and transmit them across the network.
Signal reflection
Data, or electrical signals, travel throughout the network - from one end of the cable to the other. If no special action is taken, the signal reaching the end of the cable will be reflected and will not allow other computers to transmit. Therefore, after the data reaches the destination, the electrical signals must be extinguished.
Terminator
To prevent electrical signals from being reflected, terminators are installed at each end of the cable to absorb these signals. All ends of the network cable must be connected to something, such as a computer or a barrel connector - to increase the cable length. A terminator must be connected to any free - unconnected - end of the cable to prevent electrical signals from being reflected.
Network integrity violation
A network cable breaks when it is physically broken or one of its ends is disconnected. It is also possible that there are no terminators at one or more ends of the cable, which leads to reflection of electrical signals in the cable and termination of the network. The network is falling.
The computers themselves on the network remain fully operational, but as long as the segment is broken, they cannot communicate with each other.
The concept of a star network topology (Fig. 2.) comes from the field of mainframe computers, in which the head machine receives and processes all data from peripheral devices as an active data processing node. This principle is applied in data transmission systems. All information between two peripheral workstations passes through the central node of the computer network.
Fig.2. Star topology
Network throughput is determined by the computing power of the node and is guaranteed for each workstation. There are no data collisions. Cabling is quite simple as each workstation is connected to a node. Cabling costs are high, especially when the central node is not geographically located in the center of the topology.
When expanding computer networks, previously made cable connections cannot be used: a separate cable must be laid from the center of the network to the new workplace.
The star topology is the fastest of all computer network topologies because data transfer between workstations passes through a central node (if its performance is good) over separate lines used only by these workstations. The frequency of requests to transfer information from one station to another is low compared to that achieved in other topologies.
The performance of a computer network primarily depends on the power of the central file server. It can be a bottleneck in the computer network. If the central node fails, the entire network is disrupted. Central control unit – file server implements an optimal protection mechanism against unauthorized access to information. The entire computer network can be controlled from its center.
Advantages
· Failure of one workstation does not affect the operation of the entire network as a whole;
· Good network scalability;
· Easy search for faults and breaks in the network;
· High network performance;
· Flexible administration options.
Flaws
· Failure of the central hub will result in the inoperability of the network as a whole;
· Laying a network often requires more cable than most other topologies;
· A finite number of workstations, i.e. the number of workstations is limited by the number of ports in the central hub.
With a ring topology (Fig. 3.) of the network, workstations are connected to one another in a circle, i.e. workstation 1 with workstation 2, workstation 3 with workstation 4, etc. The last workstation is connected to the first. Communication link closes in a ring.
Fig.3. Ring topology
Laying cables from one workstation to another can be quite complex and expensive, especially if the geographical location of the workstations is far from the ring shape (for example, in a line). Messages circulate regularly in circles. The workstation sends information to a specific destination address, having previously received a request from the ring. Message forwarding is very efficient since most messages can be sent "on the road" over the cable system one after another. It is very easy to make a ring request to all stations.
The duration of information transfer increases in proportion to the number of workstations included in the computer network.
The main problem with a ring topology is that each workstation must actively participate in the transfer of information, and if at least one of them fails, the entire network is paralyzed. Faults in cable connections are easily localized.
Connecting a new workstation requires a short-term shutdown of the network, since the ring must be open during installation. There is no limit on the length of a computer network, since it is ultimately determined solely by the distance between two workstations. A special form of ring topology is a logical ring network. Physically, it is mounted as a connection of star topologies.
Individual stars are switched on using special switches (English Hub – concentrator), which in Russian are also sometimes called “hub”.
When creating global (WAN) and regional (MAN) networks, the MESH mesh topology is most often used (Fig. 4.). Initially, this topology was created for telephone networks. Each node in such a network performs the functions of receiving, routing and transmitting data. This topology is very reliable (if any segment fails, there is a route along which data can be transferred to a given node) and is highly resistant to network congestion (a route that is least congested with data transmission can always be found).
Fig.4. Mesh topology.
When developing the network, the “star” topology was chosen due to its simple implementation and high reliability (a separate cable goes to each computer).
1) FastEthernet using 2 switches (Fig. 5)
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Rice. 6. FastEthernet topology using 1 router and 2 switches.
4Local network diagram
Below is a diagram of the location of computers and cable routing on floors (Fig. 7, 8).
Rice. 7. Layout of computers and cable routing on the 1st floor.
Rice. 8. Layout of computers and cable routing on the 2nd floor.
This scheme was developed taking into account the characteristic features of the building. The cables will be located under the artificial flooring, in channels specially designated for them. The cable will be pulled to the second floor through a telecommunications cabinet, which is located in the utility room, which is used as a server room where the server and router are located. Switches are located in the main rooms in cabinets.
Layers interact top-down and bottom-up through interfaces and can also interact with the same layer of another system using protocols.
The protocols used at each layer of the OSI model are presented in Table 1.
Table 1.
Protocols of the OSI model layers
| OSI layer | Protocols |
| Applied | HTTP, gopher, Telnet, DNS, SMTP, SNMP, CMIP, FTP, TFTP, SSH, IRC, AIM, NFS, NNTP, NTP, SNTP, XMPP, FTAM, APPC, X.400, X.500, AFP, LDAP, SIP, ITMS, ModbusTCP, BACnetIP, IMAP, POP3, SMB, MFTP, BitTorrent, eD2k, PROFIBUS |
| Representation | HTTP, ASN.1, XML-RPC, TDI, XDR, SNMP, FTP, Telnet, SMTP, NCP, AFP |
| Session | ASP, ADSP, DLC, Named Pipes, NBT, NetBIOS, NWLink, Printer Access Protocol, Zone Information Protocol, SSL, TLS, SOCKS |
| Transport | TCP, UDP, NetBEUI, AEP, ATP, IL, NBP, RTMP, SMB, SPX, SCTP, DCCP, RTP, TFTP |
| Network | IP, IPv6, ICMP, IGMP, IPX, NWLink, NetBEUI, DDP, IPSec, ARP, RARP, DHCP, BootP, SKIP, RIP |
| Duct | STP, ARCnet, ATM, DTM, SLIP, SMDS, Ethernet, FDDI, Frame Relay, LocalTalk, Token ring, StarLan, L2F, L2TP, PPTP, PPP, PPPoE, PROFIBUS |
| Physical | RS-232, RS-422, RS-423, RS-449, RS-485, ITU-T, xDSL, ISDN, T-carrier (T1, E1), Ethernet standard modifications: 10BASE-T, 10BASE2, 10BASE5, 100BASE- T (includes 100BASE-TX, 100BASE-T4, 100BASE-FX), 1000BASE-T, 1000BASE-TX, 1000BASE-SX |
It should be understood that the vast majority of modern networks, due to historical reasons, only in general terms, approximately correspond reference model ISO/OSI.
The actual OSI protocol stack developed as part of the project was perceived by many as too complex and virtually unimplementable. It involved the abolition of all existing protocols and their replacement with new ones at all levels of the stack. This made the stack very difficult to implement and caused it to be abandoned by many vendors and users who had made significant investments in other network technologies. In addition, the OSI protocols were developed by committees that proposed different and sometimes conflicting characteristics, leading to many parameters and features being declared optional. Because too much was optional or left to the developer's choice, different vendors' implementations simply could not interoperate, thus defeating the very idea of the OSI design.
As a result, OSI's attempt to agree on common standards for networking was supplanted by the TCP/IP protocol stack used on the Internet and its simpler, more pragmatic approach to computer networking. The Internet's approach was to create simple protocols with two independent implementations required for a protocol to be considered a standard. This confirmed the practical feasibility of the standard. For example, the definitions of the X.400 email standards consist of several large volumes, and the definition of Internet mail (SMTP) is only a few dozen pages in RFC 821. However, it is worth noting that there are numerous RFCs that define extensions to SMTP. Therefore on this moment The complete documentation on SMTP and extensions also takes up several large books.
Most protocols and specifications of the OSI stack are no longer in use, such as Email X.400. Only a few survived, often in greatly simplified form. The X.500 directory structure is still in use today, largely due to the simplification of the original cumbersome DAP protocol, which became known as LDAP and became an Internet standard.
The collapse of the OSI project in 1996 dealt a serious blow to the reputation and legitimacy of the organizations involved, especially the ISO. The biggest omission of the OSI creators was their failure to see and acknowledge the superiority of the TCP/IP protocol stack.
To select a technology, consider a table comparing FDDI, Ethernet and TokenRing technologies (Table 2).
Table 2. Characteristics of FDDI, Ethernet, TokenRing technologies
| Characteristic | FDDI | Ethernet | Token Ring |
| Bit speed, Mbit/s | 100 | 10 | 16 |
| Topology | Double ring of trees | Tire/star | Star/ring |
| Data transmission medium | Fiber Optic, Category 5 UTP | Thick coax, thin coax, |
Shielded or unshielded twisted pair, fiber optic |
| Maximum network length (without bridges) |
(100 km per ring) |
2500 m | 40000 m |
| Maximum distance between nodes | 2 km (no more than 11 dB of loss between nodes) | 2500 m | 100 m |
| Maximum number of nodes |
(1000 connections) |
1024 | 260 for shielded twisted pair, 72 for unshielded twisted pair |
After analyzing the table of characteristics of FDDI, Ethernet, TokenRing technologies, the choice of Ethernet technology (or rather its modification FastEthernet), which takes into account all the requirements of our local network, is obvious. Since TokenRing technology provides data transfer speeds of up to 16 Mbit/sec, we exclude it from further consideration, and due to the complexity of implementation FDDI technology, it makes the most sense to use Ethernet.
7Network protocols
The seven-layer OSI model is theoretical and contains a number of shortcomings. Real network protocols have to deviate from it, providing unintended capabilities, so the binding of some of them to OSI layers is somewhat arbitrary.
The main flaw of OSI is the ill-conceived transport layer. On it, OSI allows data exchange between applications (introducing the concept of port - application identifier), however, the ability to exchange simple datagrams in OSI is not provided - the transport layer must form connections, ensure delivery, control the flow, etc. Real protocols implement this possibility .
Network transport protocols provide the basic functionality that computers need to communicate with a network. Such protocols implement complete, efficient communication channels between computers.
The transport protocol can be thought of as a registered mail service. The transport protocol ensures that the transmitted data reaches the specified destination by checking the receipt received from it. It performs monitoring and error correction without higher level intervention.
Main network protocols are:
NWLink IPX/SPX/NetBIOS Compatible Transport Protocol (NWLink) is Novell's NDIS-compatible 32-bit implementation of the IPX/SPX protocol. The NWLink protocol supports two application programming interfaces (APIs): NetBIOS and Windows Sockets. These interfaces allow computers running Windows to communicate with each other, as well as with NetWare servers.
The NWLink transport driver is an implementation of NetWare low-level protocols such as IPX, SPX, RIPX (Routing Information Protocol over IPX) and NBIPX (NetBIOS over IPX). The IPX protocol controls the addressing and routing of data packets within and between networks. The SPX protocol ensures reliable delivery of data by maintaining the correct transmission sequence and acknowledgment mechanism. The NWLink protocol provides NetBIOS compatibility by building a NetBIOS layer on top of the IPX protocol.
IPX/SPX (from the English Internetwork Packet eXchange/Sequenced Packet eXchange) is a protocol stack used in Novell NetWare networks. The IPX protocol provides the network layer (packet delivery, an analogue of IP), SPX - the transport and session layer (an analogue of TCP).
The IPX protocol is designed to transport datagrams on connectionless systems (much like IP or NETBIOS, developed by IBM and emulated by Novell), and provides communications between NetWare servers and end stations.
SPX (Sequence Packet eXchange) and its improved modification SPX II are transport protocols of the ISO 7-layer model. This protocol guarantees packet delivery and uses a sliding window technique (a distant analogue of the TCP protocol). In case of loss or error, the packet is resent, the number of repetitions is set programmatically.
NetBEUI is a protocol that complements the NetBIOS interface specification used by the network operating system. NetBEUI formalizes a transport layer frame that is not standardized in NetBIOS. It does not correspond to any specific layer of the OSI model, but covers the transport layer, network layer and LLC sublayer of the data link layer. NetBEUI interacts directly with NDIS at the MAC level. Thus, it is not a routable protocol.
The transport part of NetBEUI is NBF (NetBIOS Frame protocol). Nowadays, NBT (NetBIOS over TCP/IP) is usually used instead of NetBEUI.
As a rule, NetBEUI is used in networks where it is not possible to use NetBIOS, for example, on computers with MS-DOS installed.
Repeater(English repeater) - designed to increase distance network connection by repeating the electrical signal "one to one". There are single-port repeaters and multi-port repeaters. In twisted pair networks, a repeater is the cheapest means of combining end nodes and other communications devices into a single shared segment. Ethernet repeaters can have a speed of 10 or 100 Mbit/s (FastEthernet), the same for all ports. Repeaters are not used for GigabitEthernet.
Bridge(from the English bridge - bridge) is a means of transmitting frames between two (or more) logically heterogeneous segments. According to the logic of operation, it is a special case of a switch. The speed is usually 10 Mbit/s (switches are more often used for FastEthernet).
Hub or hub(from the English hub - activity center) - a network device for combining several Ethernet devices into a common segment. Devices are connected using twisted pair, coaxial cable or optical fiber. A hub is a special case of a concentrator
The hub runs on physical level OSI network model, repeats a signal arriving on one port to all active ports. If a signal arrives on two or more ports at the same time, a collision occurs and the transmitted data frames are lost. This way, all devices connected to the hub are in the same collision domain. Hubs always operate in half-duplex mode; all connected Ethernet devices share the available access bandwidth.
Many hub models have simple protection against an excessive number of collisions arising due to one of the connected devices. In this case, they can isolate the port from the general transmission medium. For this reason, network segments based on twisted pair are much more stable than segments on a coaxial cable, since in the first case each device can be isolated from the general environment by a hub, and in the second case, several devices are connected using one cable segment, and, in case large quantity collisions, the hub can isolate only the entire segment.
Recently, hubs have been used quite rarely; instead, switches have become widespread - devices that operate at the data link level of the OSI model and increase network performance by logically separating each connected device into a separate segment, a collision domain.
Switch or switch(from English - switch) Switch (switching hub) According to the principle of frame processing, it is no different from a bridge. Its main difference from a bridge is that it is a kind of communication multiprocessor, since each of its ports is equipped with a specialized processor that processes frames using the bridge algorithm regardless of the processors of other ports. Thereby overall performance A switch typically has much higher performance than a traditional bridge, which has a single processing unit. We can say that switches are new generation bridges that process frames in parallel.
This is a device designed to connect several computer network nodes within one segment. Unlike a hub, which distributes traffic from one connected device to all others, a switch transmits data only directly to the recipient. This improves network performance and security by freeing other network segments from having to (and being able to) process data that was not intended for them.
The switch operates at the data link layer of the OSI model, and therefore, in general, can only unite hosts of the same network by their MAC addresses. Routers are used to connect multiple networks based on the network layer.
The switch stores a special table in memory (ARP table), which indicates the correspondence of the host MAC address to the switch port. When the switch is turned on, this table is empty and the switch is in learning mode. In this mode, data arriving on any port is transmitted to all other ports of the switch. In this case, the switch analyzes data packets, determining the MAC address of the sending computer, and enters it into a table. Subsequently, if a packet destined for that computer arrives on one of the switch ports, that packet will be sent only to the corresponding port. Over time, the switch builds a complete table for all its ports, and as a result, the traffic is localized.
Switches are divided into managed and unmanaged (the simplest). More complex switches allow you to manage switching at the data link and network levels of the OSI model. They are usually called accordingly, for example Level 2 Switch or simply abbreviated L2. The switch can be managed via Web interface protocol, SNMP, RMON (a protocol developed by Cisco), etc. Many managed switches allow you to additional functions: VLAN, QoS, aggregation, mirroring. Complex switches can be combined into one logical device - a stack, in order to increase the number of ports (for example, you can combine 4 switches with 24 ports and get a logical switch with 96 ports).
Interface converter or converter(English mediaconverter) allows you to make transitions from one transmission medium to another (for example, from twisted pair to optical fiber) without logical signal conversion. By amplifying the signals, these devices can overcome limitations on the length of communication lines (if the restrictions are not related to propagation delay). Used to connect equipment with different types of ports.
Three types of converters are available:
× RS-232 converter<–>RS-485;
× USB Converter<–>RS-485;
× Ethernet Converter<–>RS-485.
RS-232 converter<–>RS-485 converts the physical parameters of the RS-232 interface into RS-485 interface signals. Can operate in three reception and transmission modes. (Depending on the software installed in the converter and the state of the switches on the converter board).
USB converter<–>RS-485 - this converter is designed to organize an RS-485 interface on any computer that has a USB interface. The converter is made in the form of a separate board connected to the USB connector. The converter is powered directly from USB port. The converter driver allows you to create USB interface virtual COM port and work with it as with a regular RS-485 port (similar to RS-232). The device is detected immediately when connected to the USB port.
Ethernet Converter<–>RS-485 - this converter is designed to provide the ability to transmit RS-485 interface signals over a local network. The converter has its own IP address (set by the user) and allows access to the RS-485 interface from any computer connected to the local network and with the appropriate software installed. To work with the converter, 2 programs are supplied: Port Redirector – support for the RS-485 interface (COM port) at the network card and the Lantronix configurator, which allows you to set the converter’s connection to the user’s local network, as well as set the parameters of the RS-485 interface (transmission speed, number of data bits, etc.). The converter provides completely transparent data reception and transmission in any direction.
Router or router(from the English router) - a network device used in computer networks data transmission, which, based on information about the network topology (routing table) and certain rules, makes decisions about forwarding network layer packets of the OSI model to their recipient. Typically used to connect multiple network segments.
Traditionally, a router uses the routing table and the destination address found in the data packets to forward the data. By extracting this information, it determines from the routing table the path along which the data should be transmitted and routes the packet along this route. If there is no described route in the routing table for an address, the packet is discarded.
There are other ways to determine the forwarding route of packets using, for example, the source address, the upper layer protocols used, and other information contained in the network layer packet headers. Often, routers can translate source and recipient addresses (NAT, Network Address Translation), filter the transit data stream based on certain rules to limit access, encrypt/decrypt transmitted data, etc.
Routers help reduce network congestion by dividing it into collision and broadcast domains, as well as packet filtering. They are mainly used to connect networks different types, often incompatible in architecture and protocols, for example, for combining Ethernet local networks and WAN connections using DSL, PPP, ATM, Frame relay, etc. protocols. A router is often used to provide access from a local network to the global Internet, performing functions address translation and firewall.
A router can be either a specialized device or a PC computer that performs the functions of a simple router.
Modem(an abbreviation made up of words mo duulator- dem odulator) is a device used in communication systems and performing the function of modulation and demodulation. A special case of a modem is a widely used peripheral device for a computer that allows it to communicate with another computer equipped with a modem through a telephone network (telephone modem) or a cable network (cable modem).
The end network equipment is the source and recipient of information transmitted over the network.
Computer (workstation), connected to the network, is the most versatile node. The applied use of a computer on a network is determined by the software and installed additional equipment. For long-distance communications, a modem is used, internal or external. From a networking point of view, the “face” of a computer is its network adapter. The type of network adapter must match the purpose of the computer and its network activity.
Server is also a computer, but with more resources. This implies its higher network activity and importance. It is advisable to connect servers to a dedicated switch port. When installing two or more network interfaces (including a modem connection) and the corresponding software, the server can play the role of a router or bridge. Servers generally need to have a high-performance operating system.
Table 5 shows the parameters of a typical workstation and its cost for the local network being developed.
Table 5.
Work station
 |
System unit.GH301EA HP dc5750 uMT A64 X2-4200+(2.2GHz),1GB,160GB,ATI Radeon X300,DVD+/-RW,Vista Business | |||||||
| Computer Hewlett-Packard GH301EA dc 5750 series. This system unit equipped AMD processor Athlon™ 64 X2 4200+ with a frequency of 2.2 GHz, 1024 MB DDR2 RAM, hard drive 160 GB, DVD-RW drive and Windows Vista Business installed. | ||||||||
| Price: RUB 16,450.00 | ||||||||
 |
Monitor. TFT 19 “Asus V W1935 | |||||||
| Price: 6,000.00 rub. | ||||||||
| Input Devices | ||||||||
| Mouse | Genius GM-03003 | 172 rub. | ||||||
| Keyboard | 208 rub. | |||||||
| total cost | RUB 22,830 | |||||||
Table 6 shows the server parameters.
Table 6.
Server
 |
DESTEN System unit DESTEN eStudio 1024QM | |||||
| CPU INTEL Core 2 Quad Q6600 2.4GHz 1066MHz 8Mb LGA775 OEM Motherboard Gigabyte GA-P35-DS3R ATX Memory module DDR-RAM2 1Gb 667Mhz Kingston KVR667D2N5/1G - 2 Hard drive 250 Gb Hitachi Deskstar T7K500 HDP725025G LA380 7200RPM 8Mb SATA-2 - 2 Video adapter 512MB Zotac PCI-E 8600GT DDR2 128 bit DVI (ZT-86TEG2P-FSR) DVD drive RW NEC AD-7200S-0B SATA Black ZALMAN HD160XT BLACK housing. | ||||||
| Price: RUB 50,882.00 | ||||||
 |
Monitor. TFT 19 “Asus V W1935 |
|||||
| Type: LCD LCD technology: TN Diagonal: 19" Screen format: 5:4 Max resolution: 1280 x 1024 Inputs: VGA Vertical scan: 75 Hz Horizontal scan: 81 KHz | ||||||
| Price: 6,000.00 rub. | ||||||
| Input Devices | ||||||
| Mouse | Genius GM-03003 | 172 rub. | ||||
| Keyboard | Logitech Value Sea Gray (refresh) PS/2 | 208 rub. | ||||
| total cost | RUB 57,262 | |||||
The server software includes:
× operating system WindowsServer 2003 SP2+R2
× ABBY FineReader Corporate Edition v8.0 (server license)
× Network administration program SymantecpcAnywhere 12 (server)
Workstation software includes:
× Operating system WindowsXPSP2
× Antivirus program NOD 32 AntiVirusSystem.
× Software package Microsoft Office 2003 (pro)
× ABBY FineReader Corporate Edition v8.0 software package (client license)
× Network administration program Symantec pcAnywhere 12 (client)
× User programs
For real networks, an important performance indicator is network utilization, which is a percentage of the total bandwidth (not divided between individual subscribers). It takes into account collisions and other factors. Neither the server nor the workstations contain tools for determining network usage; special hardware and software tools such as protocol analyzers are designed for this, not always available due to the high cost.
For busy Ethernet and FastEthernet systems, 30% network utilization is considered a good value. This value corresponds to the absence of long-term downtime in the network and provides sufficient reserve in case of peak load increases. However, if the network utilization rate is 80...90% or more for a significant time, then this indicates that the resources are almost completely used (at a given time), but does not leave a reserve for the future.
To carry out calculations and conclusions, you should calculate the performance in each network segment.
Let's calculate the payload Pп:
where n is the number of segments of the designed network.
P0 = 2*16 = 32Mbit/s
The total actual load Pf is calculated taking into account collisions and the magnitude of access delays to the data transmission medium:
 , Mbit/s, |
(3) |
where k is the access delay to the data transmission medium: for the Ethernet family of technologies – 0.4, for TokenRing – 0.6, for FDDI – 0.7.
RF = 32*(1+0.4) = 44.8 Mbit/s
Since the actual load Pf > 10 Mbit/s, then, as expected earlier, this network cannot be implemented using the Ethernet standard, it is necessary to use FastEthernet technology (100 Mbit/s).
Because Given that we do not use hubs in the network, there is no need to calculate the double signal turnaround time. (There is no collision signal)
Table 7 shows the final calculation of the cost of a network built on 2 switches. ( Option 1).
Table 6.
Table 8 shows the final calculation of the cost of a network built on 2 switches and 1 router. ( Option 2).
Table 8.
| № | Name | Price for 1 unit. (rub.) | Total (RUB) | |
| 1 | RJ-45 plugs | 86 | 2 | 172 |
| 2 | RJ-45 UTP cable, lev.5e | 980m. | 20 | 19 600 |
| 3 | TrendNet N-Way Switch TEG S224 (10/100Mbps, 24 port, +2 1000Mbps Rack Mount) | 2 | 3714 | 7 428 |
| 4 | Router, Router D-Link DIR-100 | 1 | 1 250 | 1 250 |
| 5 | Work station | 40 | 22 830 | 913 200 |
| 6 | Sunrise XD Server (Tower/RackMount) | 1 | 57 262 | 57 262 |
| Total: | 998912 | |||
As a result, we get two network options that do not differ significantly in cost and meet the standards for network construction. The first network option is inferior to the second option in terms of reliability, even though network design using the second option is slightly more expensive. Hence, best option To build a local network, there will be option two - a local network built on 2 switches and a router.
To ensure reliable operation and improve network performance, changes to the network structure should be made only taking into account the requirements of the standard.
To protect your data from viruses, you must install antivirus programs(for example, NOD32 AntiVirusSystem), and to restore damaged or mistakenly deleted data, you should use special utilities (for example, the utilities included in the NortonSystemWorks package).
Although the network is built with a performance reserve, you should still take care of network traffic, so use the administration program to monitor the intended use of intranet and Internet traffic. The use of NortonSystemWorks utility applications (such as defragmentation, cleaning the registry, fixing current errors using WinDoctor), as well as regular anti-virus scanning at night, will have a beneficial effect on network performance. You should also divide the loading of information from another segment in time, i.e. try to ensure that each segment addresses the other in the time allotted to it. The installation of programs that are not related to the immediate area of the company's activities should be prevented by the administrator. When installing a network, it is necessary to mark the cable so as not to encounter difficulties when servicing the network.
Network installation should be carried out through existing channels and ducts.
For reliable operation of the network, it is necessary to have an employee responsible for the entire local network and involved in optimizing it and increasing productivity.
Peripheral equipment (printers, scanners, projectors) should be installed after the specific assignment of work station responsibilities.
For preventive purposes, the integrity of the cables in the secret floor should be periodically checked. When dismantling the equipment, you should handle the equipment carefully so that it can be used again.
In addition, it is necessary to limit access to the server room and to cabinets with switches.
1. V.G. Olifer, N.A. Olifer - St. Petersburg. Peter 2004
2. http://ru.wikipedia.org/wiki/
3. V.M. Shek, T.A. Kuvashkina " Guidelines for course design in the discipline Computer Networks and Telecommunications" - Moscow, 2006
4. http://catalog.sunrise.ru/
5. V.M. Shek. Lectures on the discipline “Computer networks and telecommunications”, 2008.
Today there is a gradual increase in the number of Internet users, which will certainly require the correct organization of local networks. Thanks to the use of modern technologies, data transfer can easily be ensured between individual computers that are installed within a single enterprise or commercial organization. It is worth noting the fact that at each of the possible stages of creating this communication line, a full-fledged design must be carried out. It is important to note the fact that such computer networks can be connected both through wired and wireless methods, each of which has some individual features and characteristic features.
What are the stages of designing an enterprise local computer network? In this case, it is worth highlighting the following:
When designing an organization’s local computer network, you will definitely need to pay attention to the following properties of the communication line, which will allow you to quickly resolve the issue of employee interaction:
It will not cause problems when specialists are called in to complete the task. The cost of such an operation is determined individually.
