Infrastructures of data networks
Model IEEE 802
We already saw in subject 1 on the different organizations who try to put a little order with respect to the criteria to be able to communicate the different devices within a network. The IEEE, in years 80, a group of engineers of this organism began to as much settle down the protocols for WIFI as for the cable (Ethernet). Of this form it is spoken of 802,3, protocol 802,11, etc.
Project 802 defines aspects related to the physical wiring and the data transmission and therefore, touching the low levels but of the model OSI
Before home to work in the configuration of router and seeing the options that this one offers to us, we must know some important aspects of the same.
In the first place we will speak of the IP.
So that two machines communicate in the space of Internet, they need to have assigned a direction of residence. This is the IP, so that our router of house it can have an IP of the 192.168.3.245 type. They always have the form of 4 groups of separated numbers by points and not being majors that 255.
But we have 4 computers to our router, those do not have that IP commented before, but it has another one for internal communication.
Therefore, we reached the conclusion that is an IP that leaves outside our house and that is given by the servant of access to Internet that we phelp (the ISP) and that is public flame IP and other than are internal in our house, that is called private IP.
Point 4.4.2 of the book NAT speech, (Network Address Translation) that is the translator of network directions and what it does is to identify what equipment of our network is making a request to Internet so that once solved (already has router the information) redirija to the applicant. Example:
Equipment 3 with 192.168.1.33 direction makes the request to the www.articlesgarage.com page and the 192.168.1.34 equipment to the finder of google. Everything leaves by router that it looks for the information on the internet. Once it has the answer of the respective servers, the one of technology the offer to the equipment that finishes in 33 and the one of google to which it finishes in 34.
Graphics mode, we will see this image where one is how they are the IP within application NAT router
Within the Routers we have possibility of assigning concrete specific ports to IP of our network.
In order to extend this information, we are going to see the work carried out by several authors gathered in this link.
We will see that differences exist between IP private and public, along with the classes that exist in this video.
Now we will see this other, where something different from the previous one appears something. It tries to discover it.
Activity on IP In the following image, imagines it structures of the IP according to the class. We must demonstrate that the principle in the rank and the end is in agreement with the conditioners of the class, for example, for the class To, it begins in 184.108.40.206 and it finishes in 127.255.255.255 because the first bit in the byte of network is 0. To demonstrate it for each class.
Activity of ability. Before home to work with router homemade, we must make clich3es with RJ45. Although the subject of cables comes a little but ahead, we will make this practice by necessity to use it in the following one. Therefore, we took 10 RJ45 and pieces from network cable. We will make 4 clich3es of about 20 or 30 cm in length. We will verify it in tester. In the end, we will make the clich3e that we will use actually of router. For the connection, to use the conexionado EIA/TIA 568B (to see it in app electrodroid)
In the image of the left, one imagines types of connectors rj 45 and rj11 both. First he is typical of the networks dew data and rj11, is the appropriate one for the telephony networks. In order to make a cable with the corresponding connector, a crimpadora is used. We will make some clich3e with this valuable tool.
Although a criterion exists for makes a clich3e of connection (to see it in page 27), although, evidently, if the same criterion in a side and the other of the cable settles down, the connection is correct for the normal networks (without being crossover cable).
If we phelp attention to a pin before being mounted, this one has a series of laminae, that to the being pushed by the crimpadora, penetrate in the cable, doing contact with the same. Once used, he cannot return to be reused, although this type of pin is very economic.
At the time of putting a connector RJ45, we have a cable criterion that is indicated in page 27 of the book. It is necessary to say that the connections between router and device (PC) are point-to-point, therefore if one adopts another norm (always the point to point is respected), we are not going to have problem some. Particularly, in a four domestic network where we must connect 3 or PC of the family, we can adopt the criterion of the color codes of the resistance, who always we remember it very and to put them of minor to major, of this form we have of left to right cables would be:
Brown, target-brown, orange, green, target-green and blue, target-blue target-orange,
Practice 1. Using criterion EIA568A, to test some with connectors and crimpadora. After verifying that they are made or (two or three connectors) make a clich3e and verify that works using a computer. First to see the theory on connectors RJ45
Practice 2. Router homemade it has a series of functions unknown for the great majority of users. This first practice (of formation, investigation and exhibition) has several sections that we happened to enumerate
To do before the practice. As routers has been manipulated previously by other users, we must do some first verifications.
- Search the manual in Internet of the model that we are using
- To pass router to the values. For it we must resetear router
- To verify in the manual access direction IP when router
- To see as they are the keys of access to the Control Panel (Usuary and password)
- To verify that the lights of the port are ignited
- To see in our PC, that direction IP is within the rank of the directions of router. For it, in the computer, to go to Home - > cmd - > ipconfig (To see adapter Internet). Also the network configuration can be seen
- To verify the IP valid
- To do ping when router (to the access IP)
- April the navigator and in the bar of directions to put the access IP to enter with the access keys.
Once finished these points, already we can work with the device. To come to realise the steps that are specified and that must be picked up in a practice to raise it the cloud (DRIVE). To consider that to connect the devices so what can bring about conflicts with the network of the classroom and, therefore, we do not have to use the Ethernet cable of the classroom. To use connected only router to the computer.
Before continuing, to look at specific the following connection where the form that we must to put to router in cascade.
- We are going to create subred. for it, we created the IP of access of the form 192.168.X.1, where X is the value that we will give by work groups. The number of the list of students can be put in X.
- To verify that we have access to Internet.
- To change the SSID (that contains marenostrum)
- To open the network so that other users connect themselves. To look at each one of the options that router has and to consult to the 20 minutes who has been connected.
- With the filters MAC, he proves the options available in each model. You do the adjustments so that a mobile connects but not the one of the companion.
- Of all the options that you have seen in each one of the models, to make a manual with the most interesting options where he indicates himself what can be done and the route. If in some of the options you want to add some image, to make a screenshot
- He investigates, using Internet, some form to change MAC of a network card.
- To until today make a point of restoration to the computer. To install some applications of management of networks, such as SELFISHNET or NETCUT
- Of the seen applications (you can see others), you do a summary of the same emphasizing his pros and cons
- You must make sure that the manual includes each one of the sections of the practice of router of page 110 of the book. Especially, to verify with a companion who is connected to your network, CANNOT use the program to raise to data a servant (filezilla) and another yes it can. (1*. To see details down but)
- NOTE. This practical one is open (you cannot send nothing definitive until all the points are closed. The time to elaborate it and to send the work can go up to around the 3 weeks.
Once finalized the manual, to send it to the mail of profe. The work is due to expose in class as appraisable activity.
In the technology of access by waves as it is WIFI, we have a great freedom at the time of connecting devices with a saving of time and considerable money, but it has the serious problem of which it turns out to be vulnerable to attacks of third parties. we have already seen that modifying MAC, we take a first step to avoid this situation. In addition there are other forms, as encriptar data, restricting ranks of IP, etc.
Practice 2. To realise in group of 2 a work on the WIFI security where the different systems take shelter to accede to a deprived network, with programs of audit and the solutions that we must take to avoid that situation
2,2 Transmission mediums (cable)
At the time of choosing a typical cable of data of the networks (4 twisted pairs) we must consider several factors as are the shield and the system of reinforcement that we happened to detail.
If the cable only has the 4 twisted pairs but the cover is called UTP. As always, this name comes from the English and are the abbreviations of Unshielded Twisted pair or (the other way around) Twisted pair nonscreened.
If it has protection shield, (shield) then we spoke of a cable STP.
The reference to the shield talks about to for of brhelped copper.
The intention of prancing the cables it is to diminish the interferences that are generated between external cables and the interns. It is verified that at the most it frequents is each brhelp, the interferences between cables is smaller and, consequently, the speeds of network increase.
In the figure we have the different cable types on the basis of its shield.
For example, for the second cable we have S/UTP, which specific a Shielded /Unshielded Twisted pair, that is to say, Offering/not offered to brhelp cable, therefore we have the external shield but not the intern.
In case of having as much external shield as to each pair, we spoke of a S/STP.
Aside from this, lack to comment the cable type and his section, which is important for certain cases. On the other hand, some cables protection fibers have in their interior some (plastic threads, seemed to nailon).
Activity 3. It finds out that function has that plastic type, how is called and where he is advisable to use cables with this type element.
Activity 4. To find out what cable type we have in the classroom and to try search its characteristics with respect to the speed and bandwidth
Activity 5. We have a cable of data that come from router to one of the dormitories of a house. In that dormitory etheret is necessary to make one second installation but the canalization of the house only allows to pass a single cable. It investigates how we can give two service to PC by cable (2 cables are needed). Note:
- The USA the App Electrodroid and looks at the configuration of the UTP cables.
- Sight in Internet the devices that exist to pass the signal from a place to another one through wiring
Activity 6. In a work of an office, where we have a AP and data network (joining point WIFI), we have realised works. When finishing, the twisted network works well but WIFI no. We see that of the AP we have a network cable and does not have but concertadores. What has been able to happen. Once solved the mystery, you do a complete development of this activity.
Transmission mediums (Air)
Many of the connections to Internet use the air as communication channel (WIFI). We will see in this point a problem that can arise to us within the configuration from router. The overlapping of channels.
The norm that regulates the wireless local networks (standard IEEE 802,11) specific 3 ranks of frequency to transmit the devices, that today, actually, has remained in two (2,4 GHz and 5 GHz). The majority, at the present time, works in the band of the 2,4 GHz. In this band certain channels settle down (frequencies) so that each device (to router) transmits and receives in her To that sub-band of denominates channel to him.
For example, if our router it has channel 1, we know (to see graph) that our router it can be emitting from the 2400 to the 2422 Mhz and router of the neighbor if works in channel 10, his router transmits frequencies between the 2444 and the 2466. All this is approximated. The idea is that channel 1 and the 10 does not have common frequencies, (is overlapping of no frequencies)
The 2,4 GHz, have established 14 channels, separated by 5 MHz, although according to the zone it can change, being in of 13 in Europe and 11 channels in the USA. The bandwidth that uses each channel to operate is of 22 MHz. As in 2474 the limit of operations settles down, we have the problem that stops to put the 13 channels, many are going to be sly.
We have to do our to router to verify in what channel it is emitting and if that channel is occupied by others routers or is overlapping. For it there are very good tools (Apps) as Wifi Analyzer that gives information us of how the surrounding phantom is occupied. Also the commando can be used netsh wlan show all (to open cmd of the PC that has card wifi).
Activity 7. The Wifi Analyzer unloads the mobile and verifies how it is occupied the channels. you do a capture of image. It indicates the channel that occupies your to router. It decides where to put it and it returns to make a capture of image with the App.
Lobes of the WIFI antennas
The antennas of routers are, essentially omnidirectional, that is to say, that they radiate in the same way in all the directions. This cannot be given the geometry of the antenna, although, in a flat parallel to the ground, if it generates the same power in all the directions.
Other antennas have a certain direction by which, the transmitted energy is greater. They are unidirectional antennas, as superior imagines in the figure.
Practice 4. Using a compass and a group where the angles are reflected from 0 to 360 , to use some metallic element (it plates flat, it plates curve, softdrink can, etc) to verify how it varies the gain in a certain point and how it does to each angle. To see some video-tutorials in Internet of how having but gain wifi
Connectors for coaxial cable
For the Ethernet networks of type 10BASE 2 and 5, the coaxial cable era very used, since the rank of frequencies were greater, but the attenuation with the distance also. We show an image with the different types based on the work frequency. Of them, most common they are the SMA and VNC.
Activity 8. Looking for the erratum. In page 27 of the book we have a photography that does not agree with its legend. Using Internet or your common sense, it finds out where it is the error.
One of the ways that we must to find out if a cable (next to connectors and unions) is in good state or no, is by means of electronic tools of control (to tester), or, with specialized software that checks how the plots within the cable travel.
Some of these programs are:
- and Finally, LAN Speed Test (Lite) or in its complete version. Important. It is necessary to consider that the task that does the program is to create a document in another PC to verify the speed of load and unloading. It is necessary to select some folder in another computer and, for it, both they must be in the same work group and share the same key. According to it is the version of Windows, we will have to act differently to obtain that both they share some folders.
Practice 5. To unload the LAN Speed program test (lite) to verify the connection that exists between your PC and swicht.
In a radio frequency network it is necessary to use connectors to transmit the signal from an equipment to another one, but that step implies the emission of electromagnetic interferences, that can harm to surrounding equipment. Each connector is appropriate for a type of application, being but small, the generally, but appropriate ones for elevated systems of frequency but. Other aspects are important as their mechanical characteristics (resistant to external forces), resistance to the climatology, price, size, etc. Other characteristics talk about to the electrical properties as:
- Reflection coefficient. In order to have a good feedback in the system, the conductive interface dielectric it is necessary to do it smallest possible.
- The impedance. A same type of connector usually becomes in the two typical impedances of use, that are 50 and 75 Ohms.
- The Rank of frequencies. Each connector has a maximum value of frequency, from which, the connector can generate problems in the network. To see table for each connector
- The losses of insertion. They depend on the work frequency and vary between 0.15 dB and 0.9 dB. For this reason, it is very important to use the smaller number of connectors in the circuit of RF.
- the maximum tension. Maximum value of the tension that it supports
- Tendency to create electromagnetic interferences in the surroundings
As we see, the election of that small element is very important and for this reason, he is advisable to consult the characteristics of the manufacturer before giving use him in a RF network
Activity. An optical fiber cable has, aside from the own optical fiber, series of layers between which they emphasize the layer of Kevlar. It investigates on this material and because they make it so appropriate to incorporate it in the cable. It investigates that it is the Mylar and what another name receives.
the waves serve us to contact with their advantages and disadvantages. (To see types in page 29). It is possible to emphasize that, when we make transmission between two terrestrial points, the frequency that we used is most important. The signals of greater frequency (more penetrating) require direct vision between both points whereas if the frequency is low, thanks to the reflection of the ionosphere.
Hub and Switch. In the subject of Internet and networks, we have, to simplified way, the difference between these two devices
We will now see some videos on connectors of fiber.
Processes to install a connector
One of the important aspects but of the facilities of a local area network, within the premises, is the disposition of the conductive elements within the zone that we want to give service of light, data, telephony, TV, etc.
One of the ways but habitual in the use of canals (left image) with different sections (light and data) to take the services to the jobs.
Usually they make in PVC, and some already they come drilled. It is necessary to be careful of not mixing cables and applying some monitoring system of the functionality of each, for example, if we took 5 lines of cable of data, to apply lines of colors, at least at the home and aim, to identify them without needing another measurer.
In same the image we have important data on aspects that repel on their longevity, this is
- Resistance to blows
- It suspends
- Resistant to the ultraviolet radiation
What it can seem to us a triviality can get to be a great problem, and the rodents are it.
The problem in this case is called butyl rubber, that is not another thing that the material that surrounds to the optical fiber and copper cables, being the outer shell of the same and that an authentic delicacy for the rodents is. In many cities they are bringing about collapse in different service areas. It is necessary to consider that our cable has this anti-erosive label.
In the market we found a range for all the tastes and, given the aesthetic shock that can cause, some alternatives as strips have been developed that incorporate strips leds, other that simulate wood tables, socles with space for cables, etc.
With respect to the technical ground, search in Internet the different models from supports, grounds and grids of positioning and.
Practice 6: a) To make a study to provide service to a room where it is lodged 10 jobs where it is necessary to have 6 takings of current, network data (rj45) and taking of telephone. The space between a position and another one is of 4 meters and the room has some dimensions of 8 Xs 20 meters. To see the option of technical ground and canalization on ground. To make a budget being used the spreadsheet with real data, specifying supplier, manpower, licenses, etc.
b) To both make a study on projects being specified pros and against of each system in addition to aspects that we would have to exhibit the client so that it decides on one or the other system.
c) To enclose file with technical drawing of the option of canals and technical ground being used the suitable symbolism.
Control of access to means
When we must mass media use only (cable, by wifi. ) and two computers wish to transmit information at the same moment, can be produced collisions of data in means that we use. This is something similar when in a social gathering are 3 or four people speaking at the same time, the result is that you do not find out to you don't mention it. It is necessary a mediator who of the word or, as in the fish markets, to remove the slip of paper from the turn. Something similar is what it happens in the networks and we are going to see two otherwise the important ones, that they are the token ring and the CSMA/CD.
The CSMA/CD is the employee in the Ethernet and consists of the attempt to transmit information when the means are free. If the means exist some equipment then using, the computer hopes a little while random and returns to try it. In the case of the WIFI signals, the process is very similarity, giving rise to protocol CSMA/CA
In the Token ring, (it is at the moment not used in designs of networks) the information is to circulate and the turn has it assigned of correlative form (one goes the turn to the other).
We will see this video where it is explained you are two techniques
1* to raise information a servant that we have contracted and, of this form, to update our content Web, the programs are used type FTP. One of them is filezilla, that is gratuitous and easy to form. You must lower it to be able to make the practice. In addition, to use it, we must have access to a servant, thus, if you do not have a contracted lodging, is necessary to register itself in some gratuitous one.
In the image of down we have the window that is when opening filezilla
We at the outset have four boxes for a fast connection to our servant, that are:
- Servant. Usually it is the IP of the servant who gives hosting to you (or of payment if we want better services)
- Name of user. He is the user who has been generated when registering in hosting
- Password. Just like before
- Port. It is the port by which we are going to transmit the data. Usually he is 20 or 21
These previous data the company of hosting generates them and they do not facilitate them for being able to work with them.
Finally, the image of above shows two differentiated sections the left and the right. So simple it is to raise as to lower data as dragging a folder from a window to another one. The window of the left represents what we have in our PC and the window of the right which is in hosting.
- It explains what is MAC, and so that they are used within router
- What is MAC spoofing?
- The algorithms of protection of routers for WIFI are .........................................................
- Because the cables of data come to twisted pairs?
- It draws a cable of data S/STP where all the details of the same are seen (including the colors)
- How the connectors for the cable of data and the one of telephone are called
- Optical fiber cable types. Characteristics
- That function has the Kevlar and Mylar (PET) in the fiber cable?
- In the connection of a fiber connector, we have a step that consists of sandpapering making a movement of 8. Because?
- It explains the protocols of Control of access CSMA/CD and CSMA/CA
- The most habitual connectors to connect coaxial cables are ...........................
- Differences between Hub and Switch
- It explains because, if the Earth is curved, it is possible to be communicated two people between Spain and Australia. The answer reasons.
- 14 Dibuja and explains how it would be the installation with cable in a building of three plants where we have 20 jobs
Puzzle of networks.
To complete each horizontal and vertical line considering separated that can have group of two or but words by spaces
The purpose of this task is to realise a complete complete technical study to install a data network in the premises (cybercafe, office, etc) and to carry out the adapted tasks you practice of the same (assembly of the elements within the classroom).
It consists of two parts.
A ) Theoretical part.
- We must make the project of a task that is asked for, choose by the student. Once decided (it can be a banking office, a building of offices, etc) if possible the planes on scale are due to make the photos of the site and to realise. Openoffice, proficad or CorelDraw can be used the programs.
- The technical work of office must be gathered in a memory (pdf) where the points of situation of the premises are added, solution decision and because (technical ground, canals.), if permissions are required, to justify the elements that settle, characteristics of the components, planes, budget, conditions of the budget, temporalizaci³n, modification of facilities (possible increase of the contract of electricity, etc) and all those points that must be included in their execution
- On the basis of the positions and disposition of the same, to study that solution is the best one on the basis of the price of each element
- To calculate the material necessary to execute the installation.
- Search in Internet the best distributors
- To do in a total budget, spreadsheet of the work
- To enclose in separate document, the technical descriptions of each component or equipment that are going away to install. For example, if it is a computer, we must say what component has and its characteristics.
- In one of the planes, to add the jobs
- The delivery of the practice must contain within a folder, the following elements: a) pdf with the memory and basic file of data
Considerations of the theoretical part (technical Office)
- The closet must be determine the proportions to lodge at least swich, patch panel and pasacables. In addition, we must tell that for great facilities usually one leaves a 30% of space for possible extensions. In our case, we will leave the sufficient space so that a suitable ventilation exists.
- The closet must have the sufficient ventilation for refrigeration of swich, that is placed in the part superior
- At least one strip of taking of current by each 6 elements. In our case it is sufficient to let to space in the part inferior to leave an feeding taking.
- I have raised DRIVE the file elements and calculations wiring estructurado.pdf where there is more complementary information of wiring
B) Practical part. To mount a network that has two VLAN networks (to see manual of the Switch). In some of the position to lower the speed to the maximum since we do not want that position has a lifted speed to Internet.
Activity of networks. Impossibility to accede to certain contents of Internet.
In determined occasions we were with the problematic one when sailing by Internet of which we cannot accede to certain contents. One is videos, music, pages, etc that yes are of public access but that does not allow its access not to belong to the country from which they are published.
Ex: If we tried to accede to videos of BRITISH BROADCASTING CORPORATION British with subtitles through reproducer online, IPlayer, also of BRITISH BROADCASTING CORPORATION will not allow it to us.
IT IS REQUESTED:
You are of practices in a company. Your head has been with this problem in a series of clients of British origin who are based in Malaga.
And he asks to you to investigate in Internet:
of which the problem consists?
Why happen does this?
What solutions exist? Which are? Cost does money?
There are tests in the PC to state that the looked for solutions work.
It prepares a presentation in Microsoft Power Point explaining all the previous points. You will have to count it through this means to all the other employees of the company, to the head and some interested clients.
It thinks that on the quality of your presentation it depends that you gain your head so that does a contract to you of work when you finish the practices in the company.