gpon ports. What is GPON? GPON - Gigabit-capable Passive Optical Networks - Gigabit Passive Optical Network

AT modern world In the field of digital communications, GPON technology has gained immense popularity. It is considered the most promising in the world, its development in countries such as the USA, Japan, Korea, and the European Union was rapid. In many Russian cities, the number of network subscribers is in the hundreds of thousands. What is GPON technology? In this article we will try to find the answer to this question.

GPON technology: purpose and technical characteristics

This abbreviation stands for gigabyte passive optical systems. GigabitPON (GPON) is a technology that involves the construction of broadband multiservice access networks. It provides various services via optical cable with guaranteed quality: Internet, television and telephony. GPON technology provides for the installation of a fiber optic cable directly into an apartment or a private house, this guarantees a constant high speed connection to the Internet. As a result, the subscriber receives the full potential of fiber optic cable, in contrast to ADSL technology, in which the channel is allocated to one apartment building and divided among all users. GPON equipment allows you to provide Internet access speeds from 10 Mbps to 2.5 Gbps. To connect a subscriber to GPON, you need to install an ONT (Optical Network Terminal) modem, which has built-in Wi-Fi, which allows you to access the Internet from any device. Digital telephony using GPON technology allows you to connect several telephone numbers. Also available Additional services: telemetry, video surveillance, fire alarm.

Advantages of GPON technology

The advantages of this technology include the following:

Optical fiber is brought directly to the subscriber;

The channel has a high throughput;

Possibility of simultaneous connection from one device to several services;

There is no intermediate equipment in the area from the subscriber to the PBX (switches, etc.);

There is no electricity in fiber optic cable, as a result, it is not affected by moisture, and there is no danger of electric shock to the user.

Flaws

The disadvantages of GPON technology can only be attributed to the fact that the fiber optic cable is quite sensitive to kinks, so it is strongly not recommended to lay it around the apartment, lay it in baseboards. In this case, the cable may break or its capacity will decrease. The problem can be created by pets, which are downright partial to GPON technologies.

Conclusion

GPON technology services have a wide range of uses in terms of consumer characteristics and functionality. This technology is user-friendly, stable and future-proof. But there is one point that the future subscriber needs to take into account. According to unwritten rules, the modem is mounted near the hole through which the fiber is pulled, thereby reducing the length of the line. Accordingly, it is necessary to provide a 220 V socket near the installation of the optical terminal.

While traveling on the global web for each user, characteristics such as data transfer speed and the absence of “gaps” are critical.

These requirements can be met by connection using xPON technology. The abbreviation stands for "Passive optical network", that is, passive optical networks. The new technique originated from PON, which guaranteed broadband multi-service access over fiber optic cables. Unlike its predecessor, communication is more powerful, this made it possible to combine all devices that receive a signal via one channel in a "digit". That is, each consumer (office, apartment, public institution) is allocated its own fiber. A maximum of 64 lines can be separated from one node, each of which ends with a special socket. One modem is connected to it, which provides communication for all devices: desktop computer, tablets, smartphones, TV, SIP phone, etc.

What are the benefits of the xPON line?

Compared to traditional methods, the new method has a lot of advantages:

• high speed data transfer - from 100 Mb/s and above;
• ease of use - additional services (anti-virus protection, parental control, and others) are configured by the provider;
• the ability to choose - the subscriber independently determines the number of connected devices and other connection parameters;
• stable quality - it does not depend on distances to distribution points.

It should be noted that xPON or has certain disadvantages. The latter include difficulties in the installation process. The disadvantages include the fact that in the event of a break, all devices are turned off at once.

How are fiber optic networks based on this technology arranged?

The scheme consists of the following elements: a subscriber node with all the necessary equipment, a distribution cabinet and a socket for connecting a modem. Cables are pulled to the houses, where they are connected to cabinets installed in the basements of buildings. Then, each subscriber is extended its own fiber, which is fixed in a special socket. This connection scheme is used by many domestic and foreign Internet providers.

Information structures in the last ten years have stepped very far forward - today you will not surprise anyone with unlimited broadband Internet at speeds of 10Mbps or more. Modern network building has quickly gone beyond the boundaries of cities - backbone network building is actively developing. And if everything is more or less clear with the highways (we laid it - we sell it), then in the cities there is now a different situation: there is a tough struggle for consumers of provider services. Cities are completely divided into sectors, which are entirely controlled by a particular provider. Under such conditions, the process of expanding the client base is seriously hampered by the fact that, in plain language, clients are over. You can compete only by improving the quality of service (including the use of FTTx technology, and specifically FTTB and FTTH), but even here competition is no longer possible - any, even the smallest provider, is able to lay fiber to the entrance. As a result, everyone faced such a problem: “There is no one to connect, there is nowhere to expand.”

But in fact, the situation is not as bad as it seems, because a person is a very peculiar animal and lives everywhere, including outside the city. Villages, towns, villages - there are plenty of customers, and everyone wants (in comparison with mobile or satellite counterparts) fast, high-quality and relatively cheap Internet (as well as television and telephone, and, preferably, in one box). The problems of connecting such clients are their remoteness from the main switching nodes and, as a result, the high cost of connection and serious problems with maintaining the network infrastructure of a remote area in working order.

Many providers have made an attempt to apply the already established model of FTTH (Fiber To The Home) "urban type" to provide users with their services - we throw a multi-fiber cable, we install active equipment - everything works. Only expensive, inconvenient and scary - intermediate equipment stands anywhere, washed by rains, winds, eaten by insects and infested with birds. In addition, active network equipment is affected by two factors that are not subject to any statistics and logic: thunderstorms and lovers of wire cutters. And everything would be conveniently solved by construction office space, but expensive, problematic (on the part of the bureaucracy) and not always possible. And then an alternative approach entered the networking scene. PON technology, dormant for the time being on the shelves.

pon(Eng. Passive Optical Network - passive optical network) is a rapidly developing, most promising technology for broadband multiservice multiple access over an optical fiber, using wave separation of the receive / transmit paths and allows you to implement a single-fiber tree-like "point-to-multipoint" topology without the use of active network elements in branch nodes. In other words, there are few fibers, no intermediate active equipment, zero (well, almost zero) influence of weather conditions, a convenient WDM system for transmitting data from the "Internet factory" to the client and back over one fiber. Active equipment in this network is available only on the provider side (in a clean, dry and cool server rack) and on the subscriber side (in the attic, in the hallway, on the good old pole, etc.). Ideal for both remote sparsely populated areas and the urban private sector.

1.2 Types of PONs.

Even at a time when all the forces of the best minds of our compatriots were directed to "cutting" the Superpower, a group of several European telecommunications companies created a consortium to implement the idea of ​​multiple access over a single fiber, called FSAN(Full Service Access Network). The goal of FSAN was to develop general recommendations and requirements for PON equipment so that equipment manufacturers and operators can coexist together in the competitive market for PON access systems. The result of the work of FSAN was a number of PON standards:

ITU-T G.983

APON (ATM Passive Optical Network);

BPON (Broadband PON);

ITU-T G.984

GPON (Gigabit PON);

IEEE 802.3ah

EPON/GEPON (Ethernet PON);

IEEE 802.3av

10GEPON (10 Gigabit Ethernet PON);

APON and BPON are morally obsolete at birth, GPON is not too developed due to the high (relative to GEPON) cost, and also because of the organic unwillingness of many to work at 2.5G speeds, 10GEPON is still under development / debugging / testing. There is also EPON, which is no longer of interest to anyone either (100Mbps is now only enough for a dozen users, and the equipment is not much different in price from its older brother GEPON). As a result, only GEPON remains, which today meets the requirements of most providers for connecting remote subscribers (the transfer rate "there" and "back" is 1Gbps, while up to 64 network terminals can be located on one fiber).

1.3 How GEPON works.

As mentioned above, GEPON is a full-fledged network built on passive optical components throughout from the provider to the subscriber.

Installed on the provider side OLT(eng. Optical Linear Terminal - Optical Linear Terminal) - L2 switch with all the ensuing functionality, having Uplink ports (for connecting your loved one to the L3 router) and Downlink ports (for client needs). The OLT from the award-winning Chinese manufacturer BDCOM, for example, has 2 optical Gigabit Uplink ports, 2 "combo" Gigabit Uplink ports (2 optical + 2 copper), and 4 Gigabit Downlink PON ports. The OLT is managed both through the terminal port and with the help of all your favorite protocols such as SNMP, SSH and TELNET.

Installed on the client side ONU(English Optical Network Unit - Optical Network Unit), which is also sometimes referred to as ONT(Eng. Optical Network Terminal - Optical Network Terminal) - a full-fledged VLAN switch of a small size. ONU from the same BDCOM standardly has one optical gigabit port and 4 copper (100Mbps or 1Gbps). There are ONU models with a combined optical port for television and data, with ports for telephony (SIP), with a different number of copper ports, with a Wi-Fi adapter, as well as combinations of all of the above. Each ONU has a built-in MAC address filter; upon receipt of a packet, the ONU checks the ownership of the packet and, if the packet does not belong to it, discards it. The ONU is managed directly from the OLT, while the OLT considers the ONU to be a “subport” of its port, having its own ports, that is, the following hierarchy is observed: OLT port -> ONU number -> ONU port.

Between the client and the provider is a passive optical network, which has tree topology and its derivatives. The main components of a passive optical network are optical fiber and splitters(English Splitter - separator), working in the "splitter" mode in the direction of the provider-> client and in the "mixer" mode in the opposite direction. The undoubted advantage of passive equipment is its independence from power supply and ease of operation (no need to configure anything): "I installed it once - I use it all my life."

Figure 1 - Schematic diagram of the inclusion of PON

The passive optical network is shared environment among many subscribers, therefore, from the side of the OLT, TDM(Eng. Time Division Multiplexing - Temporary Multiplexing), and from the side of the ONU - TDMA(Eng. Time Division Multiple Access - Multiple Access With Time Division). In this case, the downstream (we will call it the stream from OLT to ONU) is transmitted at a wavelength of 1490nm, and the upstream (stream from ONU to OLT) is transmitted at a wavelength of 1310nm. This was done in order to leave room for CATV (analogue television), which can also be launched along the PON tree to the subscriber. CATV transmitters broadcast at either 1550nm or 1310nm, but GEPON equipment manufacturers have taken the 1310nm wavelength for UpStream to keep the client device as cheap as possible (lasers emitting at a wavelength of 1310nm are much cheaper than lasers emitting at a wavelength of 1550nm).

The cost of laser GEPON transceivers is quite high in relation to their Ethernet counterparts, and for good reason: they are very powerful. The optical budget of the GEPON system (the difference between the power of the emitter and the maximum sensitivity of the receiver) is about 30dB (for ONU this figure is in the range of 25-30dB, for OLT - 32-37dB)! This budget is enough to “punch through” more than 100 km of standard optical fiber! However, PON trees usually reach a depth of 10-15 km, with a depth limit of around 20 km. This is due to the fact that dividers introduce huge attenuation into the line (from 3 to 22 dB), providing branching and saving fiber.

It is worth noting that the GEPON standard is somewhat different from the usual Ethernet frame structure, so "non-GEPON" devices in the PON network will not work. Moreover, the IEEE 802.3ah standard was adopted relatively recently, and almost none of the manufacturers complies with it 100% (and many do not particularly want to). Because of this, there is no full cross-platform hardware compatibility (for example, ZYXEL OLT will not work with HUAWEI ONU, or HUAWEI OLT will not reveal its full potential when working with BDCOM ONU).

The technology of data exchange between ONU and OLT should be considered separately:

• any ONU broadcasts only at the time allocated for it by the OLT;
• for any ONU in the network, the OLT determines the time period during which the ONU can broadcast;
• the newly connected ONU interacts with the OLT using the protocol MPCP(eng. Multi-Point Control Protocol - Multipoint Control Protocol);
• any ONU cannot communicate with other ONUs without participating in the OLT's communication. All packets for any destination are centrally processed by one device in the network - OLT.

Figure 2 - Distribution of time intervals between ONUs

MPCP. This protocol is based on two Ethernet messages: GATE and REPORT. The GATE message is sent from the OLT to the ONU and is used to assign a temporary domain. The REPORT message is used by the ONU to inform the OLT of its status (buffer full, etc.) to help it accept the right decision about the allocation of a temporary domain. Both GATE and REPORT messages are MAC control frames (type 88-08).

Exists two modes of MPCP operation: auto-detect (initialization) and normal mode RTT(eng. Round Trip Time - the time from the moment the request was sent to the moment the response was received) and the MAC address of this ONU. Normal mode is used to assign temporary domains to all initialized ONUs.

Standard Ethernet frames in PON are slightly modified for the specifics of work in a TDM-shared environment, however, the OLT modifies outgoing packets so that output a standard Ethernet stream is obtained from the PON. In the opposite direction, the situation is similar. The structure of a standard Ethernet frame (IEEE 802.3), a PON frame (IEEE P802.3ah) and an IEEE P802.3ah control frame is shown below (Figure 3):

Figure 3 - Comparison of IEEE 802.3 and IEEE P802.3ah Frame Fields

The preamble of a standard Ethernet frame (Figure 3a) is modified by adding several service fields (Figure 3b):

• SOP(eng. Start Of Packet) - 1 byte, indicates the beginning of the frame;
• Reserve field, 4 bytes;
• LLID(eng. Logical Link Identificator) - 2 bytes, indicates the individual identifier of the EPON node. Remains open question: how many identifiers can an ONU have - one or more? The LLID is required to emulate point-to-point and point-to-multipoint connections on an EPON network. The first bit of the field specifies the frame transmission mode (unicast or multicast). The remaining 15 bits contain the individual address of the EPON node;
• CRC(Circle Redundancy Check) - 1 byte, preamble checksum (P802.3ah standard).

When a frame leaves the GEPON network, the frame preamble is converted to standard form- The tag is removed. For example, in the forward stream, the OLT modifies the preamble of each 802.3 frame entering the PON, in particular, a special LLID tag is added to the preamble. This tag is retrieved by the appropriate sublayer on the ONU where preamble recovery takes place. The ONU is in normal operation, i.e. when already registered, processes only those frames whose preamble LLID matches its own LLID. The remaining fields of the EPON frame are the same as the fields of the standard Ethernet frame:

• DA(Eng. Destination Address) - 6 bytes, indicates the MAC address of the destination station. This can be a single physical address (unicast), a multicast address (multicast), or a broadcast address (broadcast);
• SA(eng. Source Address) - 6 bytes, indicates the MAC address of the sender station;
• L/T(eng. Length / Type) - 2 bytes, contains information about the length or type of frame;
• Data field, variable length;
• PAD(filler) - the field is used to pad the frame to the minimum size;
• FCS(eng. Frame Check Sequence) - 4 bytes, frame checksum calculated using cyclic redundancy code;
• OpCode(English Optional Code) - 2 bytes, specifies the type of control frame. There are two categories of control frames that differ in the value of this field: the GATE message generated by the OLT and the REPORT message generated by the ONU;
• TS(Time Stamp) - 4 bytes, contains the timestamp of the sender;
• message– 40 bytes, actually this field contains service information necessary for the operation of the MPCP protocol.

More detailed information about the logical operation of PON can be obtained at http://book.itep.ru.

The OLT and ONU provide data encapsulation into IEEE P802.3ah modified Ethernet frames using 8B/10B channel coding (8 user bits converted to 10 channel bits).

The final PON network operation algorithm after configuration is as follows:
- ONU "listens to the line";
- The OLT receives the IEEE 802.3 standard packet from the upstream device and modifies it to the IEEE P802.3ah standard;
- OLT sends the packet to a specific destination (ONU);
- All ONUs receive the packet, but only the destination keeps it - the rest of the packet is discarded;
- ONU modifies the IEEE P802.3ah standard packet to the IEEE 802.3 standard and sends it to the client PC;
- ONU from the client PC, modifies them from the IEEE 802.3 standard to the IEEE P802.3ah standard and buffers them;
- OLT allows data transmission of a specific ONU;
- ONU broadcasts a certain amount of time, and then falls silent and "listens" to the line again;
- The OLT receives the IEEE P802.3ah standard packet from the ONU, modifies it to the IEEE 802.3 standard, and then transmits it to the upstream device.

The PON network operation algorithm for converting packets from one standard to another can be represented as follows (Figure 4):

Figure 4 - PON algorithm for packet conversion

1.4 Comparison of PON with the classic FTTH scheme for connecting subscribers.

In classical FTTH, for example, 256 subscribers in the private sector need 256 optical fibers to connect. 256 fibers is a lot of very thick and expensive cables, as well as a whole bag of problems associated with their laying, switching and other unbearable routine.

In order for traffic to “walk” along these fibers, N switches are needed: N-1 access switches (subscribers will connect to them) and one for aggregating traffic from access switches. To solve the current problem, for example, the well-known D-Link DES 3200-28F needs 11 pieces (this is for access), D-Link DGS 3120-24SC needs one (this is for aggregation). Add to all this SFP modules, media converters, as well as problems with the power supply of all these devices (what did you think?!), placement (yes, under the roof, in warmth and dryness!) And administration - and the headache does not go away .

And now imagine all this not in an urban environment (where any attic is almost a server room, and any basement is a safe harbor for optics output), but in the harsh conditions of the private sector (without ubiquitous power lines, without a developed sewer infrastructure, without free premises under placement of active equipment)! And if you calculate how much fiber is dead weight (they removed one fiber from an 8-fiber cable, sent it to the subscriber, and then this fiber is used no more often than solar eclipses occur) - it becomes sad and hands drop.

When using GEPON for the same task, you need only 4 fibers, one OLT with SFP modules (8 pieces, 4 of them for Ethernet UpLink, 4 for PON DownLink), 256 ONUs (one for each client, they are powered directly from the client socket and all happy), as well as a set of splitters and PON boxes (or couplings) for working with the cable and placing these same splitters in them, and sometimes the ONUs themselves. The administrator's work will be limited to managing the OLT (ONUs are logically an "extension" of the GEPON ports of the OLT). Power supply - only on the subscriber's side and in the server room. Everything is easier, isn't it?

In addition, one should take into account the fact that it is easy and simple to start analog TV on an already built PON circuit (Figure 5):

Figure 5 - Application of PON as a medium for using CATV

So, positive sides PON:

• Minimal use of active equipment;
• Minimization of cable infrastructure;
• Low maintenance cost;
• Ability to integrate with cable TV;
• Good scalability;
• High density of subscriber ports.

At the same time, when considering GEPON technology, it is necessary to take into account its features, especially in comparison with point-to-point lines: the bandwidth shared between subscribers (the common environment may not be suitable for the client in terms of security), passive splitters make it difficult to diagnose the optical line , possibly the impact of a malfunction of the equipment of one subscriber on the work of the rest, less benefit in case of implementation at the construction stage.

Figure 2 - Distribution of time intervals between ONU

To support the assignment of time domains using the OLT, the IEEE 802.3ah group has developed a protocol MPCP. This protocol is based on two Ethernet messages: GATE and REPORT. The GATE message is sent from the OLT to the ONU and is used to assign a temporary domain. The REPORT message is used by the ONU to inform the OLT of its status (buffer full, etc.) to help it make the correct decision to allocate the temporary domain. Both GATE and REPORT messages are MAC control frames (type 88-08).

Exists two modes of MPCP operation: autodetection(initialization) and normal mode. The auto-detect mode is used to detect newly connected ONUs and determine RTT(eng. Round Trip Time - the time from the moment the request was sent to the moment the response was received) and the MAC address of this ONU. Normal mode is used to assign temporary domains to all initialized ONUs.

Standard Ethernet frames in PON are slightly modified for the specifics of work in a shared by principle TDM environment, however, OLT modifies outgoing packets so that output from pon it turns out standard ethernet flow. In the opposite direction, the situation is similar. Structure of the standard Ethernet frame (IEEE 802.3), PON frame (IEEE P 802.3ah ) and control frame IEEE P 802.3ah shown below (Figure 3):

In economically developed countries, this technology has long been widespread. It began to develop intensively from the distant 90s.

The rapid adoption of the technology in Europe, as well as in Japan and the United States, has been greatly influenced by its high network speed, reliability and low operating costs.

Today, in the cities of the Russian Federation, some providers also provide their subscribers with access to communication services through this progressive technology, thanks to which only one cable makes it possible to simultaneously use telephony, interactive television and high-speed Internet.

Technology Description

Answering the question: “What is GPON?”, Firstly, its capabilities should be noted.

The technology provides several services simultaneously via one communication channel, while ensuring a high speed of information exchange, which is especially important during the broadcast of sound and video.

Secondly, it would be advisable to familiarize yourself with the decoding of some abbreviations. The operation of a passive optical network, or "PON" (Passive Optical Network) for short, is to provide multi-access over a single fiber optic wire through the multiplexing of the receive-transmit paths.

PON technologies quickly improved and the Ethernet PON standard was developed to provide high-speed information transfer, and soon an upgraded version of Gigabit EPON was released, which is now second only to gigabyte passive optical systems, i.e. "GPON" for short.

The decoding of this abbreviation in English language looks like this: Gigabit capable Passive Optical Network.

Pros and cons

The technology involves the use of a light channel to transmit information via fiber optics.

It is this circumstance that imposes some disadvantages, although the advantages of the technology more than cover the accompanying disadvantages.

GPON provides for the laying of fiber directly into the subscriber's home and allows you to reach the speed of work on the world wide web up to 2.5 kbps.

To connect, the client needs to install an optical terminal or, in the original language, "Optical Network Terminal" - abbreviated as ONT. It is usually provided by the provider itself.

The terminal, or as it is used to be called in our country, the ONT modem is already equipped with a Wi-Fi module, so there is no need to extend the cords further from the device around the apartment.

To transmit a light pulse through a special cable, it does not consume as much energy as to ensure the reception and transmission of data over a metal conductor.

It is quite difficult for attackers to intercept such a signal, and also fiber optic cable not afraid of electromagnetic interference. This determines the reliability and quality of communication.

The GPON network makes it possible to provide the subscriber with high-quality telephone communication using an IP telephone, several numbers on a single line, and, if the client wishes, you can save the number after changing the place of residence.

Of the main advantages, it should also be noted the high throughput and the simultaneous use of various services.

The word "passive" is not in vain used in the name of the technology. It implies operation without the use of intermediate equipment, that is, there are no switches and similar equipment on the line between the client and the station.

As you know, any device has a habit of breaking down and needs to be serviced periodically, not to mention the fact that it does not work without a power supply. These factors add up to the economic benefits of GPON.

Since there is no electrical energy in the optical fiber, there is no danger for the subscriber to suffer from a current discharge, and such a cable is absolutely indifferent to high humidity.

The user should be well aware of all the shortcomings of the technology. This will help him avoid unjustified financial expenses and maintain his personal psychological health, not only his own, but also that of specialists from service center provider.

Optical fiber is very easy to damage by mechanical impact on it. Even minor local bends often lead to damage, therefore, in order to avoid such risks, it is recommended to install the modem as close as possible from the entry point to the gpon house.

Often, small cable crushing, for example, with a chair leg, led to a decrease in its throughput. Typically, devices are mounted right at the entrance to the living space.

The wire must be located out of reach of pets, as cats and especially dogs feel it is their primary duty to test the strength of the cable with their teeth.

Restoring a fiber or replacing it for a subscriber is an expensive procedure, and it is better to immediately stop all non-warranty cases in the bud.

The main disadvantage, which is indicated by engineers, relates to the economic issue of payback for the introduction of technology. The infrastructure of the appropriate equipment and cables pays off only if there are a large number of subscribers and the payback period is relatively long.

This leads to the introduction of GPON only in cities, and residents far from them have to continue to be content with the Internet using outdated transmission technology. copper wires, fortunately, that telephone cables in Russia are laid almost everywhere.

GPON equipment

The equipment for connection is provided by the provider, for example, you can make an application to Rostelecom in many cities of the Russian Federation. Sometimes equipment is rented or purchased by the user with fiber optic connectivity.

Therefore, the nuances must first be clarified with the communication service provider. It will also help in the future to properly configure the connected subscriber devices (PC, TV, telephone, mobile gadgets, etc.).

A cable is laid in the client's house and a gpon optical terminal is installed, next to which is located electric socket from which the instrument will be powered.

This terminal is designed to convert the fiber optic interface to an Ethernet interface.

Terminal models have different functionality, so before installation, you should clarify the possibility of connecting devices via Wi-Fi channel, IPTV, telephony, etc.

How to connect?

Due to lack of awareness, users are often extremely surprised to learn that the connection procedure includes drilling a wall in an apartment (otherwise how to insert a cable into a room), installing equipment (technically ignorant subscribers ask a perplexed question: “Why is there a device and cabling in the house?” do you need wireless internet?” etc.).

In addition, if the client needs interactive TV, then a special set-top box must be connected. Some need to ensure the operability of a fixed telephone and connect a security fire alarm, video surveillance.

Therefore, the instruction for resolving the issue of how to connect depends on each specific case and the wishes of the person who has entered into an agreement with the provider.

During the connection, the fiber from the client's home to the distribution equipment is laid in reliable boxes that protect the fragile material. In the connection diagram, this is a key point.

Connection of ONT with PC (if Internet service is available) and ONT with IPTV set-top box (if interactive TV service is connected) is performed via twisted pair cable.

The only thing that is required from a person who decides to connect GPON is to choose a provider and, by visiting his website or by phone, contact him.

Next, clarify the possibility of connection by providing the exact address and, if the outcome is positive, apply for connection. Further, having concluded an agreement with the provider, meet the installers at home, who, having installed the terminal, will set up communication services.

Then, if the subscriber wants to change services, they are adjusted remotely.

Internet GPON

GPON technology is able to provide the user with Internet at a speed of up to 500 Mpbs, and this is with the simultaneous operation of several devices. The network is not adversely affected by radio and magnetic interference.

Internet via Gigabit PON is reliable, since there is no active equipment on the Client-PBX line, which means that there is simply nothing to fail.

The throughput value reaches 1 Gpbs, however, routers that do not have enough power to transfer such a volume of virtual data often become a weak link in the chain.

Of course, the characteristics in numbers may not tell people anything, but even a value of 0.5 Gpbs is more than enough for the average user, for example, at such a speed, you can download a full-length movie in HD quality in a few minutes, and such files weigh about seven gigabytes .

Tariffs

The Russian Federation is a large country stretching for thousands of kilometers from west to east. It should be noted that the farther to the east, the more expensive the tariffs. It is more profitable to connect the services of Russian providers offering GPON tariffs in cities in the western part of the country, for example, in Moscow.

But the most expensive fiber-optic communication will cost citizens living on Far East. It is recommended to find out the latest prices on the official resource of the communication service provider.

A popular provider in the Russian Federation that provides Internet via fiber is RTK.

For example, for residents of cities in the central part of the country, on average, the provider will need to pay monthly services in the amount of 350 rubles, but this is at a minimum access speed. The billing by the provider is subject to the generally accepted formula: “The more the subscriber pays money per month, the cheaper each megabit costs”.

The billing already includes the cost of equipment provided to the client by the company. Given this fact, the prices of tariffs for users are justified.

So MGTS provides equipment to customers free of charge. The initial setup by the company's specialists is free of charge.

Conclusion

The technology is attractive and versatile, however, in the absence of a sufficient customer base, it is unprofitable, therefore, it is used only in apartment buildings large cities.

If the user lives in the private sector, remote from optical communications, then it is not profitable for the provider to pull the infrastructure to him.

Of course, only if you do not agree with all the inhabitants of the suburban village and connect to high speed internet collectively.

GEPON (Gigabit Ethernet PON)- the technology of data transmission on a fiber optic network gaining popularity. Its essence is in a tree-like point-to-multipoint topology, when only one fiber optic channel is used to build a network for tens and hundreds of subscribers.

The network tree is built in such a way that the branch for the subscriber is separated from the main trunk as close as possible to its location. Used for separation passive distributor - splitter. This is fundamentally different from conventional fiber optic network topology, which is predominantly point-to-point architecture, and each branching of the line requires the installation of active network equipment.

GEPON structure

To build an optical passive network In addition to fiber optics, the following are used:

• OLT(Optical Line Terminal) - optical line terminals that provide communication between the PON network and external networks;
• Modules SFP OLT for PON connection, with increased power and signal encoding;
• ONU(Optical Network Unit) - the end network unit (modem) at the subscriber.
• Splitters- passive splitters in network nodes.

The GEPON tree structure assumes various construction options, from the simplest - 1 OLT, 1 SFP OLT module, 64 ONUs and required amount splitters for branching to "multi-trunk", where all ports of the OLT can be used, as well as several OLTs or multi-port models.

GEPON Network Architecture Diagram:

The picture also clearly shows how the data is transferred. All packets leave the central node, at the end point each ONU "picks up" only its own, designated by an identifier.

On the way back, packets from subscribers are collected into one channel. PON networks use TDMA protocol when packets from different points are transmitted at different times.

In addition, incoming and outgoing traffic, as well as TV traffic are separated.

Diagram of the complex structure of GEPON:

When designing complex passive optical network schemes, it is important to remember that one channel cannot be divided by more than 64 subscriber units, and the optical budget of the system should be taken into account.

Optical budget systems - the difference between the transmit power of the OLT and the receive sensitivity of the ONU.

Max Distance, to which you can stretch a passive optical network, taking into account the losses on the channel - 20 km.

Maximum number of subscriber devices connected to one "tree" PON - 64 . However, the final number of subscribers may be greater if a switch is connected after the ONU. Here, restrictions are imposed only by the table of MAC addresses of the OLT and ONU, and, of course, by the channel bandwidth.

Minimum speed per 1 subscriber- 16 Mb/s (1024 Mb/s for 64 ONUs).

Equipment for the GEPON network

Optical line terminals - OLT

These devices are second-level switches equipped with Uplink ports - for connecting to external data sources (Internet, TV, telephony) and Downlink - for the PON network.

OLT-terminals are issued with designations:

• AC - the switch is powered by a standard 220 V power supply;
• DC - the terminal needs a 36-72V direct current source;
• 2-AC 2-DC - the presence of 2 power supplies, the main one and an instant backup.

Subscriber terminals (modems) - ONU

Devices on the subscriber's side, optical terminals equipped with one PON port and one or more, depending on the model, ports for connecting client equipment. There are models with cable TV output.

Splitters

Inexpensive compact simple devices that do not require power supply, heating cabinets, control and settings. Them the main task- traffic separation on the way from the provider to the subscriber, and traffic mixing - on the reverse. There are welded (with the possibility of uneven distribution of traffic) and planar (equilateral). Branching - from 1*2 to 1*128.

Technology Disadvantages

• Signal attenuation at each branch node. As a result, in a network with 64 ONUs, the total attenuation can exceed 20 dB.
• The need for maximum bandwidth of all devices. Although each specific subscriber receives from 16 Mbps, each point of the network (ONU) is forced to support the maximum throughput of GEPON - 1 Gbps.
• Insufficient level of data security. The technology is definitely not suitable for financial and similar organizations.
• Difficulty of modernization. In order to increase network bandwidth, it may be necessary to replace the entire cable on the backbone.
• Interference in the operation of the entire PON with one faulty ONU transmitting a continuous light signal in the opposite direction. It is possible to provide WathDog to control accidental breakdowns, but it is much more difficult to prevent the actions of intruders.
• Difficulty in finding faults. Splitters, due to their extreme simplicity, are unable to help in determining the faulty section of the network.

Benefits of GEPON

• Economical consumption of optical cable. In fact, GEPON technology can reduce the length of the cable infrastructure by almost three times.
• Lack of active equipment at the network nodes, which significantly reduces the cost of its implementation and maintenance.
• High sustained speed- up to 1 Gbps.
• Efficient load distribution in the channel. Theoretically, the speed for each subscriber will be the channel capacity / number of subscribers. In fact, if some subscribers in this moment they do not use their entire traffic band or are not connected at all - the speed of the rest increases.

As you can see, GEPON has both its pros and cons. However, the growing popularity shows that many still find more advantages.

In one of our next issues - answers to FAQ relative to passive fiber optic network.