Driving forces of the market. Traditional telephone networks (TDM-telephony)

Access network technologies

xDSL technology

xDSL -- (Digital Subscriber Line - digital subscriber line) a family of technologies (ADSL, ADSL2, ADSL 2+, SHDSL) that can significantly expand bandwidth subscriber line local telephone network by using efficient line codes and adaptive methods for correcting line distortions based on modern achievements in microelectronics and digital signal processing methods.

Figure 1.12 -- Network structure built on DSL technology

ETTH Technology

ETTH is a way to permanently connect to the Internet using the protocol fast ethernet. The use of broadband access using ETTH technology allows consumers to connect to the network at a speed of 100 Mbps with a consistently high connection quality. ETTH connection does not depend on the presence of a telephone line. Laying is carried out to each connected building optical cable, to which, in turn, a house node is connected with further wiring directly to the subscriber.

By connecting to the ETTH network, the user receives a single channel, a telecom operator and a single bill for services.

Figure 1.13 -- Network structure built using ETTH technology

xPON Technology

xPON(Passive optical network) -- technology of passive optical networks.

Figure 1.14 -- The structure of the network built on PON technologies

Distribution access network PON is based on a tree-like fiber-cable architecture with passive optical splitters at the nodes, represents an economical way to provide broadband information transmission. At the same time, the PON architecture has the necessary efficiency of increasing network nodes and bandwidth, depending on the current and future needs of subscribers.

The essence of the technology and its attractiveness lies in the fact that the network is built using passive optical power dividers (splitters) that do not require power supply and maintenance (passive network).

Feature: 100% optical channel to the client's home / office, which allows not only to increase the signal quality, but also to increase the transmission speed tenfold (up to 1Gb / s). When connecting using PON technology, an optical cable is installed in the subscriber's apartment / office and terminal equipment is installed - an ONT optical modem.

Traditional telephone networks (TDM-telephony)

Switching based on frequency division techniques was developed with the expectation of transmitting continuous signals representing voice. In the transition to a digital form of voice representation, a new technology multiplexing, focusing on the discrete nature of the transmitted data. This technique is called Time Division Multiplexing (TDM).

The equipment of TDM networks - multiplexers, switches, demultiplexers - operates in the time-sharing mode, servicing subscriber channels in turn during its operation cycle. The cycle of the TDM equipment is 125 μs, which corresponds to the repetition period of the voice measurement in the digital subscriber channel. This means that the multiplexer or switch manages to serve any subscriber channel in time and transmit its next measurement further along the network.

Ethernet To The Home (ETTH). Using Ethernet to access the Internet is a relatively new technology that has not yet become widespread in the Russian expanses.

The purpose of the Ethernet To The Home solution is to transmit data, voice and video over a simple and inexpensive Ethernet network. Uniqueness this decision is that the use of Ethernet with fiber as a transmission medium allows for gigabit network access directly from customer premises. There are a large number of buildings on the market that are attractive to network service providers: office complexes, commercial business parks, hotels, universities, apartment buildings, cottage settlements. To provide Ethernet connectivity for new buildings to metropolitan area networks (MANs), network service providers typically use optical fiber. The main advantages of such access are speed and distances - up to 100 km without intermediate amplification and regeneration with potentially unlimited bandwidth. Gigabit Ethernet (1 Gbps and 10 Gbps) has become attractive in terms of price/performance ratio, becoming a good choice for backbone applications when building not only dedicated corporate networks, but also operator networks Metro Ethernet. Single-mode and multi-mode fiber as well as Category 5 twisted-pair are the best options for in-building wiring. Designed as a technology local networks Ethernet technology provides huge and cheap bandwidth compared to DSL, cable modems, and wireless solutions. A typical architecture is the implementation at the first stage in each apartment in any room of the building 10- or 100-Mbit Ethernet channels connected to the switch serving this building. Gigabit or multi-gigabit Ethernet connections are available to connect buildings to the MAN fiber optic city network. Traffic aggregation of ring city networks is carried out by means of a layer 3 switch.

According to various analysts, it is ETTH technology, and not DSL, that is the best broadband solution for subscriber access. ETTH doesn't have all the speed and distance limitations that DSL has that prevent it from being considered a long-term broadband option. ETTH is recognized as a long-term solution even though it requires a significant initial investment. This technology has a longer service life and does not have any significant limitations. And although there are several access technologies today to provide broadband multimedia connections, ETTH guarantees the service provider significant benefits relative to competitors. From a service provider's point of view, this technology allows them to compete successfully with more cost-effective solutions such as DSL. VDSL, one of the varieties of DSL, can even serve as a temporary solution last mile inside the building. Another, slower, temporary alternative would be an Ethernet radio.

An Internet connection that transmits several types of signals, provides a constant high-quality connection to most users of our country, is called ETTH. This is an abbreviation based on the first letters of the English expression "Ethernet to the home". An ETTH connection guarantees a data transfer rate of up to 1 Gbps and can be used to send encrypted packets, voice or video messages without a modem or other devices that create noise or interference.

How it works

ETTH technology is a system of transmitters that is connected into a single whole by optical fiber. Any data from the user's computer is translated into the language of numbers, divided into equal parts (packets) and transmitted over the cable. Each packet contains service information, which contains information about its recipient, serial number, and so on. When the first part arrives at the addressee, the computer checks whether all the data has arrived or not. If everything is in order, it requests the next one, and so on, until all the information has been delivered.

When all the packages are in place, they are combined into a single whole, from the language of numbers they are translated into the format of video, text, audio. For all of the above, the system spends fractions of seconds.

The packets travel from transmitter to transmitter over a fiber optic cable. In its middle are quartz or polymethyl methacrylate fibers that conduct light. Thanks to this method of transmission, data travels intact over long distances at great speed. For example, this year, scientists from the NICT Network System Research Institute, together with representatives of Fujikura Ltd, presented a new type of three-channel (or three-mode) fiber, through which information was transmitted at a speed of 159 terabits per second over a distance of 1045 kilometers.

To make ETTH affordable and reduce the cost, specialists combine several types of installed equipment:

the main optical node, which serves up to 250 subscribers;
backbone optical fiber connecting optical nodes;
a switch that receives information from a node and sends it to subscribers connected to it;
subscriber receiver;
twisted pairs (eight copper wires, twisted in pairs, covered with a braid, to which a ninth steel wire can be added for strength), connecting subscribers and switches into a network of one node.

This gradation makes it possible to simultaneously use expendable materials different costs (compare: a meter of optical fiber will cost 1,500 - 2,000 rubles, twisted pair cable UTP CAT 5e - about 15 rubles). Devices of different cost, make ETTH technology cheap for the end subscriber.

Advantages of information transmission over optical fiber

The cable used in ETTH technology, equipment, make it possible to:

create networks that will have a minimum number of equipment failures due to its small number and high reliability;
combine a large number of subscribers into a parallel digital network;
reduce the amount of extraneous noise, interference that affects the quality of communication;
maintain a high speed of data exchange between optical nodes;
use existing networks, such as cable television, to connect to the Internet;
get the best price / quality ratio for the end subscriber.

Modern OUs operate at a distance of up to 100 km from each other, maintaining a high-quality broadband Internet connection.

What the user needs

For ETTH technology, equipment is divided into two categories:

required by the provider;
needed by the subscriber.

In order to bring high-quality Internet to the apartment using fiber optics, the provider must first install an optical node. Then lay a fiber optic channel between the node and the switch. When the switch is installed, subscribers can be connected to it. That is, before the network starts working, the provider needs to spend money and effort on its preparation.

A twisted pair cable is brought into the client's apartment, which will connect the Wi-Fi router to the switch. Inside the apartment, you can conduct a twisted pair cable from the router to the computer or put a Wi-Fi receiver on the PC. Mobile gadgets like a laptop or tablet are equipped with such a receiver during the production process.

It makes no sense to bring fiber into a house or apartment for two reasons:

Cable cost: even if we take an apartment building in which the switch is on the technical floor, each floor is about three meters of cable, about 6 thousand rubles.
End equipment: Signals from the computer are transmitted using a network card. In the standard version, it is “sharpened” for working with copper wire (twisted pair). To connect a fiber optic cable to a PC, you will need to change the network card.

Today, large providers work with ETTH: significant investments are required to provide a connection for a city, region, home. They not only cover all the costs of equipping modern lines, but also offer users routers that are compatible with their network for rent for a symbolic amount of about a ruble per month. Thanks to this approach, most Russian cities are provided with high-quality broadband Internet using ETTH technology.

Information technology and telecommunications are already firmly established in our everyday life- have become part of not only business, but also modern life. Perhaps there is hardly a person today who does not understand the benefits of using these tools. Now it is impossible to imagine an office of even a small company that does not have a local network and access to the Internet.

At the dawn of the Internet, dial-up access was the main technology for accessing the network. Today, the vast majority of companies and private users have access to world wide web using a variety of broadband technologies such as: xDSL (mainly ADSL), DOCSIS (cable television networks), Ethernet To The Home - ETTH. These technologies provide the user with a number of advantages compared to dial-up access, these are, and much higher transmission speeds, moreover, over a symmetrical channel, i.e. transmission and reception of data is carried out simultaneously, and the absence of a dial-up procedure, i.e. the user is always connected to the Internet, and a free telephone line while browsing the Internet.

Of all broadband technologies, ETTH seems to be the most interesting and promising, as it is the fastest, and also supports symmetrical data transfer rates to and from the user. Theoretically, ADSL2+ technology allows the user to receive data at speeds up to 24Mbps and send at speeds up to 3Mbps, but the actual connection speed is very dependent on the quality of the cable line. Operators providing cable TV access using DOCSIS 3.0 technology typically provide users with a channel at up to 152Mbps (4-channel DOCSIS), although the maximum speed can reach 400Mbps (8-channel EuroDOCSIS). The speed from the user in both options is up to 108Mbps. The actual speed in DOCSIS 3.0 depends on both the quality of the line and the number of connected users, since the provided bandwidth is divided among all users connected to one CMTS port. Unlike the described technologies, ETTH allows you to deliver to the user and receive data from him at speeds up to 10Gbps. Of course, service providers do not offer such speeds to end users, but theoretically it is possible. Typically, the end user is provided with a 100Mbps or 1Gbps port. Moreover, given speed can be completely utilized by one subscriber (it is not divided into several users, as in DOCSIS or PON) and does not decrease when the line quality deteriorates, i.e. the connection is established, either at 100Mbps (1Gbps), or not at all if the line quality is very poor. As you can see, even today, the speeds provided by this technology are several times higher than the speeds provided by other technologies. I would especially like to note that the speeds provided to the user are symmetrical, i.e. data is received and transmitted at the same speeds, which in some situations is a very big advantage. Asymmetric technologies are suitable for users who use Internet resources, since in this case the amount of information received is much higher than that transmitted. But if there is a need to combine the local networks of two offices, or organize a video conference, or home users want to play computer games with each other, or one of the users wants to provide their resources to others, then in this case the reverse link speed can be a bottleneck.

ETTH networks are essentially the same Ethernet networks as office or corporate networks, and the same principles are used in their construction, but they still have a number of significant features that require a different approach to their design and construction. They have a large territorial distribution, which affects the choice of equipment, and the method of administration, require the use of optical fiber and related active equipment, increasing the initial cost of the project. Devices used in such networks should be able to remote control because it is nearly impossible to perform everyday administrative tasks, network monitoring, and troubleshooting locally. Such tasks should be performed centrally with the help of a special software, which allows not only to remotely administer devices, but also to localize the problem, receive certain notifications from the equipment, remove the necessary statistical data from it, etc. Provider networks have a low concentration of clients, which does not allow using major centers switches equipped with devices with high port density. On the contrary, devices with a small number of ports are required, which are installed separately and at the same time have a high level of manageability. The lack of access to client machines, the inability to configure them and install the necessary software on them leads to the application of specific security measures. The equipment for such networks is installed not in server rooms, but in anti-vandal cabinets in unsuitable rooms: in elevators, attics, and basements. Therefore, it should be as compact as possible, resistant to temperature and supply voltage fluctuations, resistant to static electricity, and it is desirable to support the possibility of being powered from low-voltage direct current sources to ensure uninterrupted power supply in case of failure of the main one.

The topology of such networks is also slightly different from office and corporate networks (Fig. 1). ETTH networks, like corporate networks, are built in accordance with a multi-layer hierarchical model, but the tasks performed by different layers and the protocols used by devices at these layers may differ from those in corporate networks. As a rule, the physical topology of the levels is also slightly different.

How are such networks built, and what functions of devices, and at what level are necessary?

The core level in such networks is often built on a ring or mesh topology. Devices of this level should have high performance and have optical 10 Gigabit ports. In order to reduce the load, all additional traffic processing tasks are removed from the kernel level. These tasks are transferred to the distribution layer, which is easily scalable by increasing the number of switches. Naturally, core-level switches must support the technologies necessary in the core: protocols that allow for device redundancy - ERPS and / or STP (RSTP, MSTP), IEEE 802.1Q and Q-in-Q for creating and forwarding virtual networks, IEEE 802.1p for quality of service, OAM/CFM for monitoring and troubleshooting, etc. In addition to the above protocols, it is necessary to support reliable and secure administration mechanisms: SNMPv3, SSL, SSH.

When building a ring topology, the question often arises which protocol to choose: ERPS or STP, because each of the protocols has its own advantages and disadvantages. The advantage of STP is that it can be overlaid on almost any physical network topology, unlike ERPS, which can be used exclusively in a ring topology. In all other respects, STP loses. ERPS has a shorter convergence time of 200ms on average, compared to 5 seconds for RSTP/MSTP. It allows you to unambiguously specify which port (RPL) and on which switch (RPL Owner) will be blocked by default, unlike STP, where this is done using priorities and is not unambiguous. In ERPS, by default, the port specified by RPL will be blocked, but if a break occurs somewhere in the ring, then, just like in STP, the blocked port is unblocked. If the connection is restored at the place of the break, then the return to the previous configuration will not occur immediately, but after some time (WTR Timer). This is done so that in the case of an unstable connection, there would be no constant rebuilding of the topology, as happens in STP.

Figure 1. ETTH network topology

Since core level switches are usually located in well-served sites and have enough links to allow any physical topology to be built, the use of the ERPS protocol is preferable at this level, as opposed to the distribution level, where the physical topology can be a limitation.

In large networks for the core level, D-Link recommends using the high performance and high functionality DES-7200 or DGS-6604 modular switches. The DES-7200 switch (Fig. 2) is available in two chassis options: 6-slot and 10-slot. In each chassis, two slots are reserved for installation of control modules, the rest are reserved for interface modules. There are a fairly large number of different interface modules that allow you to choose the desired combination of ports. The device is a highly functional and high-performance routing switch and supports a large number of protocols and technologies: MPLS, dynamic routing protocols: BGP, OSPF, RIP, multicast routing protocols (multicast): DVMRP, PIM-DM, PIM-SM, PIM-SSM, etc. The DGS-6604 switch (Figure 3) is quite new development from D-Link and is a 4-slot chassis, in which one slot is reserved for the control module, and the other three are for installing interface modules. The device offers high functionality and high performance at an optimal cost per port.

Figure 2 DES-7210 Switch

Figure 3 DGS-6604 Switch

In small networks, optical switches may be suitable for the core layer: the DXS-3600 or DGS-3620-28SC series. The DXS-3600 series includes two switches: the DXS-3600-32S (Figure 4) which has 24 10Gb SFP+ ports and the DXS-3600-16S (Figure 5) which has 8 10Gb SFP+ ports. Both switches have an expansion slot. This slot can accommodate additional modules that support various types of optical and copper ports: 1Gb/s, 10Gb/s, 40Gb/s, 120Gb/s. The DGS-3620-28SC switch (Figure 6) has 24 SFP ports (4 of which are UTP/SFP combo) and 4 SFP+ ports. Both lines of switches are L3 switches, support dynamic routing protocols: BGP, OSPF, RIP, multicast traffic routing protocols: DVMRP, PIM, and MPLS.

Figure 4. DXS-3600-32S Switch

Figure 5. DXS-3600-16S Switch

Figure 6 DGS-3620-28SC Switch

When building the distribution level, the following are used: ring, mesh or star-shaped topologies. Very often the question arises which topology to choose. Each topology has its own advantages and disadvantages. A star topology is easier to build, administer, implement various functions, and troubleshoot, but at the same time it does not have redundancy and it takes more optical cable and equipment to build it. In a ring topology, the opposite is true - it is more difficult to administer, but there is redundancy and it is cheaper. A mesh topology, on closer inspection, is a multiple ring topology. The choice of topology depends, first of all, on the presence of highly qualified specialists at the operator. If there are such specialists, and their qualifications allow you to correctly build and further maintain a ring or mesh topology, then it is better to choose them. If there are no highly qualified specialists, then it is better to stop at the star topology. Often, different topologies are used in the same network, since a feature of building ETTH networks is the inability to change external conditions for oneself, i.e. the cable is laid where it is possible to lay it, and not where you want to lay it, unlike office networks, where the route can be laid along almost any route, punching the necessary holes in the walls or ceilings and laying the cables in boxes or trays.

Distribution layer devices must support basic set required technologies: ERPS, STP (RSTP, MSTP), IGMP/MLD Snooping, 802.1Q, Q-in-Q, GVRP, 802.1p, OAM/CFM, SNMPv3, SSL, SSH, NTP. At this level, as a rule, traffic is routed, respectively, the switches must support the required protocols: OSPF, DVMRP, PIM-DM, PIM-SM, PIM-SSM, VRRP.

When choosing a protocol for routing multicast traffic, the question often arises which protocol to choose: DVMRP, PIM-DM or PIM-SM. Best Choice will be PIM-SM, since PIM-DM and DVMRP create unnecessary network load. These protocols periodically translate all available multicast groups to all their interfaces until these interfaces receive an unsubscribe from them. PIM-SM works only on request and only broadcasts to the interface those groups that the join report was in. True, in large busy networks, the use of PIM-SM can lead to significant delays between switching channels for the end user, since the report needs to go along a long route through all the switches to the multicast source, and then the requested group must return along the same or another route . To reduce these delays in the kernel, and in some cases at the aggregation level, all multicast groups are translated, and processing on request (report) occurs only at lower levels.

Depending on the size of the network, it is recommended to use switches of the DXS-3600 series (Fig. 4, 5) or DGS-3620-28SC (Fig. 6) as aggregation level switches. In some cases, an aggregation level may have several sublevels, usually two or three. Then, for the sublayer that is closest to the core, you can use switches with a large number of 10-gigabit ports, i.e. DXS-3600 series. For the next sublayer, L3 switches with a large number of optical gigabit ports and some 10 gigabit ports (for connection to the upper sublayer of the distribution layer) can be used, for example, DGS-3620-28SC. And the lowest sublevel of the distribution level can be an L2 sublevel and serve as an optical hub for combining access level switches. Switches of the DGS-3420 or DGS-3120-24SC series can be used at this sublayer. The DGS-3420 series includes two optical switches DGS-3420-28SC (Fig. 7) and DGS-3420-26SC (Fig. 8). The devices of this series support static routing and all necessary technologies and protocols: ERPS, STP (RSTP, MSTP), IGMP/MLD Snooping, 802.1Q, Q-in-Q, GVRP, 802.1p, OAM/CFM, SNMPv3, SSL, SSH, NTP, etc. The DGS-3420-28SC has 24 SFP ports (4 of which are UTP/SFP combo) and 4 SFP+ ports, while the DGS-3420-26SC has 24 SFP ports (4 of which are UTP/SFP combo) and 2 SFP+ ports. The DGS-3120-24SC switch (Figure 9) is similar in functionality to the DGS-3420 series, but has 24 SFP ports (8 of which are combined UTP/SFP) and 2 CX4 copper ports.

Figure 7 DGS-3420-28SC Switch

Figure 8 DGS-3420-26SC Switch

Figure 9 DGS-3120-24SC Switch

The level of access in ETTH networks is quite specific. On the one hand, at this level, most of the tasks of ensuring security and ensuring the quality of service are solved, i.e. the devices must be quite highly functional, and on the other hand, they must be quite cheap, since they are installed directly in homes and, accordingly, quite a lot of such switches are required. The use of small-port switches, in which the cost of a port is higher than in multi-port switches, can also lead to an overall increase in the cost of the access layer.

The access layer is built, as a rule, according to a ring or star topology. The specific functionality of access level switches depends very much on the service delivery model chosen by the operator. For example, if the operator authenticates the user by his IP address (today this is one of the most popular options), then, accordingly, the switch must support mechanisms that prevent the user from substituting his address. In D-Link switches, this feature is called IP-MAC-Port Binding. It allows you to specify the IP and MAC address of the client on the switch port, and if it is changed, the user will not get access to the network. For large operators, the use of the IP-MAC-Port Binding function is inconvenient, since the change of MAC addresses on user ports can occur quite often and the operator in this case needs to either rebind itself every time, or provide the user with the opportunity to do it on their own, for example, through the web portal. More convenient for the provider is the DHCP Snooping mechanism. In this case, there is no need for the operator to manually bind IP and MAC addresses on each port. The distribution of IP addresses in the network is done via DHCP, and the switch keeps track of which IP address was received by the client and automatically binds it to the port. In order to be able to track which IP address was issued to which port of the switch, it is necessary to support another function - DHCP Relay with the ability to insert Option 82. When using it, the switch will insert information about the switch to which the client is connected to the client DHCP request ( usually, this is the MAC address of the switch) and the port number.

Another popular authentication mechanism is the use of tunneling protocols such as PPPoE, PPTP and L2TP. The most convenient of them is PPPoE. In this case, access switches are not required to support IP-MAC-Port Binding and DHCP Snooping mechanisms, but on the client side, support for the tunneling protocol used by the provider is required, and on the operator's side, installation and support of BRAS is required. When using the PPPoE protocol, it may be useful to insert a Circuit-ID into the headers of PPPoE packets. This function is called PPPoE Circuit-ID Insertion and is similar to the DHCP Option 82 function. It makes it possible to track from which switch port the client establishes a session, allowing certain policies to be applied to this port.

If the operator provides the user with not only access to the Internet, but also some Additional services, for example, IPTV, VoIP, Video-on-Demand, then the question arises how best to do this in order to ensure the optimal quality of each service. From a technical point of view, the most convenient option for the operator is to provide each service in its own VLAN. With this model, manage services and provide each service best quality maintenance is the easiest, but this method leads to certain problems on the client side. In order for the user to receive all services, he needs to install a device that will accept tagged traffic and provide it to the user in the form of several untagged ports. If the user wants to receive all services at the same time, then he will need additional devices, such as an IP Set-Top-Box and an IP phone. The minimum cost of all three devices will exceed $200, which may be critical for a subscriber. If the operator is going to provide these devices to the subscriber, then this amount for him may be even more critical than for the subscriber, since it is more than 20 times the cost of the switch port. If the user wants to simultaneously receive all three services on his computer, then he will also fail, since each service is available only in its own port of the subscriber switch or router. Those. he will be able to receive services only individually, and each time he will need to switch his cable to a different port on the device. And if the user wants to receive services via Wi-Fi? And if the user wants to receive the service on several TVs and / or several IP phones, what will the cabling look like in his apartment?

The second way to provide services is to use dynamic wlans. In this case, data is transmitted in a normal static welan, and voice and video, respectively, in a dynamic voice (VoIP) and multicast (ISM) wean. When using such a model, there are certain problems with the classification of voice traffic. Unlike a corporate network, in a provider network it is quite difficult to separate voice traffic from everything else and place it in a separate wlan. In this case, we cannot use OUI, since we do not know which manufacturers' phones will be installed on subscribers, and we cannot use any automatic device type detection protocols, such as LLDP, since it may not be supported by these devices. OUI cannot be used also for the reason that subscribers for voice communication can use computers or communicators, as a result, their normal network traffic can get into the voice weed.

The third way of providing services remains quite popular, when voice and data transfer traffic go in one static wilan, and multicast traffic in a separate dynamic multicast wilan. In this case, it is a little more difficult for the operator to ensure the quality of services, but the subscriber is provided with an untagged port. Those. the user does not need to purchase additional devices, and he can simultaneously receive all services on his computer.

The issue of security is quite acute in operator networks, and it is much more difficult to solve it than in corporate ones. This happens because in operator networks: it is practically impossible to use organizational security measures, client equipment is not unified and the provider's technical services do not have access to it, i.e. cannot install the necessary software on it and apply the necessary policies. As a result, all security tasks must be performed on the operator's side, and not just on the operator's side, but at the access level. If all security tasks on the subscriber port are not solved, then the user, having connected to the access switch, will already be able to perform certain attacks. If the operator issues addresses to users via DHCP, it is necessary to use the DHCP Screening function, which allows you to disable the use of DHCP servers on user ports. If subscribers are authenticated by IP address, then mechanisms are needed to prevent the subscriber from changing the address, such as: IP-MAC-Port Binding or DHCP Snooping. To prevent attacks like ARP Spoofing, you need to use functions like: ARP Spoofing Prevention or ARP Inspection. If the provider's network uses the STP protocol, then mechanisms are needed to prevent attacks on this protocol. On user ports, you must enable the Restricted Role function, which prohibits the switch port from becoming root, and Restricted Tcn, which drops TCN (Topology Change Notification) packets. If there are several rings in the network, then Restricted Tcn can also be enabled on the ports of the ring switches that are connected to higher levels so that changes in one ring do not lead to the restructuring of all rings of the network. Also, it must be remembered that the STP protocol in some situations does not know how to deal with rings. Such conditions can occur when, for a switch that has STP enabled, the ring is within the same port. To avoid problems caused by such topologies, the Loopback Detection feature must be enabled.

For the access level, it is recommended to use devices of the DES-3200 series (Fig. 10), which has all the necessary functionality and includes various models with the required number of ports for connecting users: 8, 16, 24, or 48, and the required number of ports for connecting to the backbone : 2 or 4. For many, the switch of the younger DES-1210-28 / ME / B2 series is also suitable. In terms of its functionality, it resembles the DES-3200 series, but it lacks support for such technologies as: ERPS, SIM, CFM/OAM.

Figure 10 DES-3200 Series Switches (DES-3200-10, DES-3200-18, DES-3200-26, DES-3200-28,DES-3200-28F, DES-3200-28P, DES-3200-52,DES-3200-52P)

Building networks of providers is a rather specific and complex task. Such networks are not an auxiliary tool for solving basic business problems, but a means of doing business, and its success depends on how such a network functions. Therefore, it is necessary to approach the construction of ETTH networks and the selection of equipment with special care and accuracy. D-Link is committed to helping operators solve their technical and business challenges. D-Link has significant experience in designing and building provider networks. Many large projects around the world work on our equipment.

Learn more about D-Link products and solutions at the weekly free technical trainings at the company's offices. The training schedule can be found on our website at

ETTH technology from Rostelecom appeared on the telecommunications market not so long ago and, unfortunately, has not yet had time to spread everywhere. Its main advantage over its competitors is the consistently high speed of Internet access. Often, data transmission in this way is called fiber optic, which is explained by the use of this type of cable.

What is ETTH technology from Rostelecom

What is ETTH technology from Rostelecom and where is it used? The answer to this question lies in the abbreviation itself, which stands for Ethernet To The Home. ETTH is one of the most modern methods of gaining access to the Internet. Its operation is based on the Fast Ethernet protocol.

Broadband Internet access has a stable connection speed of 1 Gb / s, just like when working in your own office or home network. The technology allows you to forget about the location of the server and comfortably work with remote files, even the largest sizes.

Technically, the Internet connection to the house is made via an optical cable. Further, the signal is distributed to the apartments using a special switch installed for the house. In the house itself, from the switch to the user's network device, the signal passes through a twisted pair of category 5. Less often, you can find the laying of an optical connecting cable.

Pros and cons of ETTH from Rostelecom

Rostelecom's ETTH technology boasts high speed internet connection and stability. The latter is ensured by the fact that when using Ethernet To The Home, the quality of the connection is not affected by atmospheric factors, as is the case with DSL.

Creation new technology was justified not only by the increase in speed indicators, but also by the need to provide direct access. ETHH does not require additional substations to equalize the signal over more than 100 km of the line. The technology has become very popular among providers that provide Internet connection services to office complexes and residential buildings in large cities.

In addition to creating private and corporate networks, the performance of Ethernet To The Home is also sufficient for operator use in Metro Ethernet backbones. The speed in this case reaches 10 Gbps.

The local server communication technology provides the best cost/performance ratio by eliminating the need for complex signal conditioning.

Interesting: Compared to DSL, Ethernet To The Home can not only receive data, but also send it to the server at high speed without any delay. Two-way transfer provides the ability to comfortably work with remote files within ETTH networks.

A significant disadvantage, which does not allow to accelerate the development of fiber-optic connection type in Russia, is the need for large initial investments. Despite this, it is ETTH that is recognized as the most promising technology for broadband Internet access.

How to set up ETTH equipment from Rostelecom

To connect the Internet using ETTH technology from Rostelecom and its subsequent configuration, the user does not need to purchase expensive equipment. All costs for switches and other devices are covered by the provider. A regular network cable will be connected to the apartment, which is compatible with many models of routers.

Due to the high cost of manufacturing new network equipment and the need to lay optical fiber, providers are forced to increase the final cost of services. Therefore, there are many alternative offers on the Russian telecommunications market with cheaper tariffs and, accordingly, lower Internet access speeds.