Russian-made equipment or one day in the life of an IT specialist

    I continue the series of articles I started six months ago about Russian telecom equipment manufacturers, and more specifically, about their products.
    This time we will focus on the organization of a wireless communication channel based on Wi-Fi module Infinet R5000IL.

    First, I’ll talk about technical specifications and some of the subtleties of tuning, and deeper under the cut will be a related story about installation for those interested.


    Wi-Fi has already deeply entered our lives. But in addition to home and office applications, there is also industrial use, when directional / panel antennas are installed on both sides and the devices operate in point-to-point mode. This is our case. A link is required at a distance of five hundred meters. In general, in this mode, the distance can reach several kilometers.
    The principle of operation is exactly the same: one device acts as a base station and determines the frequency of operation. Several subscriber stations can be connected to one BS when using several antennas and a splitter (that is, the point-to-multipoint mode also works). If the BS determines the frequency of the network, then the connection speed is configured on the subscriber side and the BS is transmitted. This is done for those reasons that up to each specific client device there may be a signal of different quality.
    Available operating modes:
    2412, 2417, 2422, 2427, 2432, 2437,
    2442, 2447, 2452, 2457, 2462, 2467,
    2472, 2477, 2482.

    1000, 2000, 5500, 11000

    These are the characteristics of the modem that was in my hands. Infinet also has 5 GHz modems. Moreover, it seems that they give them preference. I suppose that this is due to the fact that in this range it is easier to obtain permissions to use frequencies, especially since mobility is not needed here at all.
    The R5000IL consists of a power supply unit, an internal module (IDU) and an external module (ODU).
    IDU is the brain of the system. It includes a radio module that performs the functions of an ADC, Fourier transform, multiplexing and modulation. In addition, he is a router. There are three software interfaces in the WanFlex embedded OS: lo, eth0, and rf. Within one BS there is a local IP addressing in the subnet.
    On the device’s case there is a power connector, Ethernet and a connector for connecting the feeder from the antenna.
    ODU in our case is a regular antenna. There are also external modules into which the radio modules are integrated. IDU with ODU is connected by means of a high-frequency cable - feeder. A splitter can be placed between them, to connect several antennas and an amplifier to increase the length of the feeder path, since its recommended length at a frequency of 5 GHz is only 1 meter.
    From my practice and the words of old-timers, I can say that the devices are trouble-free and honestly fulfill their role. Not a single gap in any weather and the speed corresponds to the declared.
    One significant drawback: in the firmware that is installed in our modem there is one serious problem - authorization does not work. Despite the configured parameters for entering the control mode, any login / password is suitable. But, most likely, in new versions this has already been fixed.

    Below, as I promised, the story of one installation.


    New work always portends a lot of interesting things. And so it happened. In less than a month in a new place, as the microaral happened. The weekend morning of May 3rd began on the roof of the old factory. It was necessary to hang this same Wi-Fi antenna to provide access to the corporate network for the organization located in this building.
    Why the weekend? Because the connection is needed for a company selling alcohol, and the old channel is no longer working. Meanwhile, soon the ninth of May ... Lost profits could be calculated in numbers with a large number of zeros.
    No, of course, I could refuse, given that this exit is not paid, but would I really be a real IT worker after that? It was always interesting to me to study new pieces of iron. And it was a chance to touch Infinet. It used to be called Revolution.
    So morning began on the roof. Someone’s optics fluttered proudly in the wind, the April Siberian cold brightened our loneliness. The modem was dismantled from another building, two hundred meters from the current installation point, so all that had to be done: install the antenna on the roof, point it in the right direction, forward the feeder (coaxial cable) to the IDU and align the antenna. Everything at first glance is simple. But if this were so, then there would not be this continuation now. By the way, when dismantling the modem and the switch, the horror of the state of the switching and server racks in modern organizations was once again revealed to me.

    The first obvious difficulty is the length of the feeder. The manufacturer recommends a cable length of not more than 1m for a frequency of 5 GHz. We have in our hands a device operating at a frequency of 2.4 GHz and about 35 meters from the server room, where the modem should be located, to the roof. Of course, we tried to probe this question first, but we couldn’t achieve any convincing answer from the support - there was no answer to the form filled out, their email was also silent, the girl said on the phone that “well, yes, one meter ”and advised to download from their website a program for calculating the path, which turned out to be in * .jar format.
    “They won’t give you a try” - that’s how we thought and decided to stretch it out of the server room - in the shortest way - down the street.

    The server room is on the second floor, there are no stairs, there are no lifts, the only way to extend the cable is to put it in the hole from the room and lift it onto the roof, tying the end to a twisted pair. That's where it all started. My partner on the roof tied a packet of bricks to a twisted pair to make it easier to lower. Needless to say, the polyethylene could not stand it and the brick flew down.

    In the photo the moment one second before the fall:

    Running back, I still did not fully understand what was happening, but I saw that there was some kind of a foreign car below and our “tag” was exactly on the trajectory of movement. From a height of 25 meters a very strong blow should have been obtained. None of us actually managed to get scared. There was some fleeting understanding of the fact that we “hit”, which quickly disappeared. The brick hit a ledge on the wall and scattered into two parts, which fell on opposite sides of the “tag” less than half a meter from it, and only dust fell on the roof.

    The second time they already did not dare to test their fate with such rationalization decisions.

    They lowered the twisted pair, tied a feeder to it with ties, and pulled it up gently untangling, so that knots and rings did not work out.

    After the cable was tightened, laid, secured everywhere with cable ties, crimped, inserted into the connectors and sealed with silicone (sealing is a mandatory step, since moisture entering the microwave cable significantly worsens its performance), we went down and turned on the modem. But he did not turn on. We were shocked - during the dismantling, we did not just turn off the power before disconnecting the antenna, but ate the feeder with side cutters. As far as I know, it is not recommended to turn on the radio equipment without a connected antenna in order to avoid failure. In our case, in general, a closure could take place.

    But panic is not our method. The power supply turned out to be from Dlink'a, that is, it had already been replaced before, and the quality of the power supplies of this manufacturer is known to everyone. Street → car → road → office → warehouse → new power supply unit of the same company and a couple more with similar characteristics → car → road →

    Between this and then

    → factory. When turned on, a squeak is heard (at least some sign of life, albeit frightening), friendly blinking of LEDs, there is an ethernet connection. But alas, nothing comes from the antenna. The device is silent on the rma bs command (information about the BS to which the modem is connected). There may be several reasons: the cable is damaged, poor contact on the connectors, the radio signal does not “push through” such a length, the radio module itself is damaged.
    Solder the contacts on the connectors below, go up. Here it should be noted that this factory was producing beer, therefore, despite the repair, there was an unpleasant smell of rotten / fermented either malt or barley (I’m far from manufacturing technology). Civilization itself ended on the fourth floor. Then began the ownership of the new owners of the building - pigeons. As my boss pointed out sharply: "They have their whole life cycle going through there." Here are the stalagmites of their litter and the dried corpses of mice and their own - and all this in a wild venhegret in one place. And it’s generally scary to step into the dark corridors. All brand-name sealant, with which the connector was abundantly lubricated, had to be removed. Solder → seal → down to the test. Unfortunately, even after soldering the connectors, the situation did not improve: rma bs

    still returns an empty string. Next step: Verification by directly connecting the IDU to the ODU. To do this, provide power to the roof. Again, twisted pair, we lift the end of the extension cord onto the roof, which was already safely lowered after fixing the antenna.

    As usual, a jumper is used to connect the modem to the feeder: a short piece of flexible thin coaxial cable, so there were no problems with direct connection: the IDU connects to the ODU through it - the connectors are the same.

    This time, rma bs showed data of something like this: the signal level was 10/7 (from BS / to BS) on a 16-point scale, which can be considered quite good.
    #1> rma bs
    rf4.1: bs (123456/11000,2437) 000435ff2876 Q=159 10/7 IP=
    Links 13, reps 13, Q=159 Rx=2 Tx=2 burst

    After connecting the laptop, setting the IP address, mask and gateway, the necessary network becomes available - fine, everything works. Accordingly, it is necessary to shorten the length of the feeder (or the feeder itself is damaged, but we immediately threw this option away as the most unpleasant). For this, there is only one possibility - placing the modem near the antenna, somewhere in the room to avoid the influence of the environment, and pulling the power cable and twisted pair.

    The room was found — the former elevator — and an antenna was actually installed on its wall ... You can also throw the twisted pair along the street, but I wouldn’t like to feed at all, just as I wouldn’t like to conduct it through the ventilation or along the stairwells. But the great power of the experiment did not fail: despite the abandonment of the building, communications, cut wires, torn electrical panels,

    there was a switch in the elevator room, on which there was electricity. The switch was powerful - Soviet with three inputs. When the contact switch is closed, sparks appeared. Theoretically, the power problem has been resolved. It remains only to find the phase and zero. The phase tester helps us establish that all three contacts are phases. But zero should be taken from somewhere? Zero comes from the cable to the metal case of the circuit breaker, and from there to the ground loop, passing through the entire room. As I was told after the installation, this is normal practice and there is nothing reprehensible in this. With grief in half, this issue has also been resolved: we stretch the power supply (the shield on one side, the device will be located on the other) and the greatly shortened feeder.

    Check the signal - there is a connection. Signal quality is significantly lower than with direct connection. But there is a connection with the main network. Apparently, the cable length is very important here. This is the case when I am ashamed of the quality of the installation in which I participated. But within the set terms and conditions, it was difficult to do otherwise. Meanwhile, the time is already approaching the end of the weekend. Half of the plans have already been thwarted, the other half in the balance. We throw a vituha into the server room, check from there - Hurray, there is a link. We seal. Finally, the work seems to be finished. Actually because of what is all the cheese boron? It is necessary to provide employees with RDP access, mail, software updates. Therefore, the last test is connecting to the remote desktop.

    It would be all over ... But does it happen when you work on Friday night or on a day off?

    Several attempts from different machines do not lead to anything, the antivirus is not updated, mail does not go. About half an hour of digging and help from above led to the conclusion that large packets do not go. Ping -l 300 is still there, ping -l 350 is gone.

    Changes on the mtu modem for various interfaces do not lead to any results. Changing the bitrate, by default set to a maximum of 11Mb / s, to 5.5Mb / s does not help. Again to the top, remove the sealant layer, unscrew the connector, pull up the extension cord to connect the modem. The situation is similar, there are no solutions.

    Desperate with a zero mood, we returned to the office that day - the morning of the evening is wiser.

    The worker’s morning on May 4th was in reading manuals, comparing configurations from similar devices. What is interesting - there are no complaints about these modems for many months of work: stable good communication, fast automatic connection. And then moving a couple of hundred meters - and does not work. Lantastica some.

    Before, I had never dealt with industrial Wi-Fi equipment and directional antennas for it. Accordingly, the control system on which it works - WanFlex - was not familiar to me. But during this time I became a little skilled in it. A team was found to analyze the number of retransmissions of packet transmission on the radio interface. In normal mode, they should be no more than 15%, but in general the network cannot be turned over, if any. In our country, their percentage turned out to be above 50. 72% of the packets at least once repeated. For comparison, at other points, the total number of retries ranged from 5-11% (we are talking about receiving). From this we can conclude that at this interval there are some serious obstacles or interference from other equipment.

    The output looks something like this:

    #1> muffer stat
    MAC out/rep in/rep
    000435ff2876 472316/132337 (00/18/21) 521770/10252 (00/01/01) =BS=
    TOTAL: 472316/132337 (00/18/21) 521770/10252 (00/01/01)

    The alcohol company is already taking its first losses, and we are moving forward at a fast pace to the location of the base station.

    The base station is exactly the same Infinet block, as I already said (the disadvantages of the impossibility of attaching to the rack: it lies on the supply of cables like in a pile of building dust) from which there is a microwave cable to the roof (20 meters) to the splitter. From the splitter, the cable diverges to two antennas - one is directed to the installed modem, the other to the other party.

    So it is: on this gap an obstacle appeared, which was not on the former, - a metal crane - exactly closing the visibility between the antennas. The first thought about transferring the antenna was recognized inhumane - and without that, quite a bit of work was done. At the suggestion of my boss, I set the bitrate to 1 Mb / s and, lo and behold, everything works. Large packages flew. We wipe our eyes, try again - it works. On this, he offers to immediately save the config and do not touch it anymore. But still, I try to put it at 2 Mb / s - it also works - config save. Later, I remembered that when connecting to 2 Mb / s Wi-Fi, noise-resistant DSSS is used instead of the productive OFDMA, and a slower, but more reliable modulation scheme is also chosen. Apparently, these factors played a role. Be that as it may, the fact is that the RDP is working,

    So on the third day, our torment with installation and adjustment ended, the mood rose, and the company suffered minimal losses. The main thing is to consider any event in life from a positive perspective.

    1) Now we have gained experience with radio equipment.
    2) I know to some extent the WanFlex interface commands.
    3) We know that it is better to seal the connectors at the very last moment, after all the tests.
    4) In no case do not cut the microwave cable with the equipment turned on and do not even unscrew it.
    5) The presence of a ping response does not mean the service is working (an obvious, it seems, fact, but nevertheless more than once it came across this)
    6) Not to consider yourself very smart and consider even stupid at first glance options is also not a new remark, and I myself have already given myself such a vow, however ...
    Sincerely yours:

    <That's what I like about my work? You sit in the office: cisco, converters, networks, TCP. The head is full of devils. Some kind of abstract clients, channels. Everything was like that of bookkeepers or businessmen, and then rrraz - and went to the fields in order to see it all live and to understand what kind of booth it was then, what kind of abstract optical cross is hanging somewhere in the locker. And see this:

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