By cable or DOCSIS - this is international standard telecommunications, which allows you to add data transmission to an existing coaxial system cable television with high throughput. This is important for both Internet users and Internet providers because it allows you to increase Internet speeds without replacing coaxial cable networks. On a practical level, consumers will need to know which DOCSIS standard is needed when purchasing a cable modem.

Modem Connection Basics

DOCSIS allows the use of cable connections to serve high-bandwidth applications. It was created in March 1997. During this period, it went through several stages of improvements. The system includes a modem located at the user's premises, as well as devices located elsewhere, usually at the central station of the provider company or at an intermediate node.

There are two main components of DOCSIS: the physical layer (PHY) and the media access control (MAC) layer. The physical layer refers to the wiring and routing equipment used, and the transmission of data across these various physical systems. In general, faster transfer speeds mean better performance. However, there are several limitations in terms of physical distance.

These restrictions affect the areas where a DOCSIS 3.0 cable modem and other infrastructure can be installed, which affects their speed and price. The MAC layer is designed to intelligently manage the vast amount of information being processed at any time, allowing for a critical level of organization that prevents frequent traffic jams caused by opposing signals.

The evolution of Internet transmission speed

Overall, there have been three different major iterations of DOCSIS over the years: 1.x, 2.x, and 3.x. The original 1.0 and 1.1 specifications had an operating limit of 38 Mbps for transfer speeds and only 9 Mbps for speed increases. As technology evolved over the next few years, it was necessary to organize operations so that cable providers had greater flexibility as speeds improved and service levels increased. This led to the creation of DOCSIS 2.0 in 2002.

DOCSIS 2.0 did not introduce new features to reduce network speed, but it tripled the speed, allowing 30 Mbps connections. The most significant changes occurred in 2008 with the introduction of DOCSIS 3.0. This new iteration was a format that significantly increased speeds to 1.2 Gbps and 200 Mbps respectively. This was a huge leap, with DOCSIS 3.0 including the introduction of channel communications.

It allows you to assemble or combine multiple channels downstream and upstream with improved speeds across the entire range. With a channel connection, the more channels present, the better. So, installing 16 channels downstream and 4 upstream or 16x4 provides fast speed, and a 24x8 system even faster.

Latest Integration Standard

In 2016, DOCSIS 3.1 was released, which led to a sharp jump in speeds, including in the downstream direction. This iteration brought speed packages of up to 10 Gbps and 1 Gbps, respectively. Today, work is already underway to develop a new iteration, usually called DOCSIS 3.1 Full Duplex. This version will support symmetrical 10 Gbps up and down speeds.

It is inevitable that the DOCSIS cable modem will continue to evolve to accommodate new technologies and user requirements around the world. Consumers should stay on top of these changes to ensure they can upgrade to cutting-edge models in a timely manner.

As 4K and UHD become more common for both wireless and wired networks, their options are increasing in terms of volume and convenience. Therefore, there are still many exciting developments to come in the DOCSIS field in the coming decades.

Buy or rent

If a user leases a cable modem from their ISP, purchasing is an option that will save them hundreds of dollars in rental fees over the life of the device. Some companies charge about $120 annually for rent, and given the low cost of modems, most will pay for themselves very quickly. Additionally, choosing a modem for your personal needs allows you to get the most out of your internet plan, and the network performs better than rental equipment.

Not every modem is suitable for all types of Internet services. Cable internet will not work with because they use different delivery methods. DSL uses the telephone's terrestrial infrastructure. If the ISP is also a landline phone carrier, you will likely need the appropriate type of DSL.

More advanced users recommend a modem and router combo if you need an inexpensive and compact replacement for a rental device. However, keep in mind that they do not give much control over the router. If one device breaks, both will need to be replaced.

How a cable modem works

It provides data transmission over cable television networks and can be connected directly to the TV socket. This places it between the user's cable connection and the computer. It can also be connected to a computer via USB or network cable. If the user wants to connect several computers, then in addition to the modem, a compatible router or a combined device is needed that will combine both functions.

The data sent by the computer must be converted into a suitable format in order to be able to transmit it on special frequencies via a television cable. Today, Internet providers mainly provide combination devices from a cable modem router, which allows you to connect via WLAN to the Internet.

Multiple devices with one IP

The ISP only provides one IP address. But a situation often arises when you need to connect several devices via WLAN in parallel to the network. This is possible if this IP address is not directly associated with the PC, but with a router that connects the internal network to the outside world. It works with a public IP address. However, the internal network uses a separate block of IP addresses.

In theory they range from 192.168.0.0 to 192.168.255.255. In practice they are almost always 192.168.1.1 or 192.168.1.50. Addresses starting with 192.168 are, by definition, always private IP addresses. Devices with the same IP addresses are located on many millions of small and large networks. Almost every personal router defaults to internal IP 192.168.1.1.

It is very important in what order the devices are turned on. First, turn on the cable modem and wait until the LED lights up, indicating that it is ready to start and connected to the Internet. Then the router is started. Experience shows that this happens a little faster than with a modem. Only at the moment when they are ready, the terminals connect to the network in any order: mobile phone, tablet, laptop, desktop PC.

Connecting and setting up the router

Setting up network equipment with routers is much easier today than before. Before you connect your cable modem, it's helpful to understand which type is best for a fast connection to avoid unwanted problems in the future. Connection to Motorola:

1. Open an Internet browser. In the address field, enter for Motorola routers: 192.168.100.1, for the modem: 192.168.0.1.
2. Press "Enter". Default username: admin. Default password: motorola, all lowercase letters.
3. Click “Login”. If you can't login with 192.168.0.1, try using 192.168.100.1.
4. Make sure that the username is: admin and the password is: motorola.
5. Make sure that the connected Motorola cable modem model begins with the letter “M”, example: MB8600, MG7550, MD1600.
6. Set the device to factory default settings. Here you will need a pin or a straightened paper clip.
7. This is done when the power is turned on. Find the RESET hole at the back of the device.
8. Press the RESET hole with a paper clip for about 25 seconds. Wait until the device connects again.

Home network with TP-Link AC1750

High-performance TP-Link AC1750 modem (with DOCSIS 3.0, equipped with a wireless router alternating current, which supports a reliable home network. It allows you to stream 4K without slowing it down. Now this incredible modem is priced a little higher than budget models, but the difference in performance makes the price point worth it. Positive traits:

1. Delivers up to 1750Mbps Wi-Fi speeds with 16 streaming and 4 upstream channels.
2. The 2.4 GHz processor supports heavy online games.
3. Equipped with internal antennas and powerful amplifiers, it can enhance signal strength and reduce interference.
4. Has convenient settings.
5. The Motorola cable modem is compatible with most Internet service providers.

Even if users have problems with the setup, the support team is available 24/7 and ready to provide assistance.

Disadvantages of the model:

1. The web interface for managing settings could be more user friendly.
2. File transfer speed could be better.

Despite a few complaints, this device still has overwhelmingly positive reviews.

Moreover, it is a device that offers excellent performance at a reasonable price.

Optimal NETGEAR home model

The NETGEAR CM500 - 1AZNAS is a DOCSIS 3.0 based cable modem that provides speeds of up to 680 Mbps and is ready to handle a wide range of connection packets. This is the best budget model because it can give you incredible speed for under $70. It is compatible with various operating systems: Microsoft Windows 7, 8, 10, Vista, XP, 2000Mac OS. Can work with most major cable internet providers. Functionality - simultaneous execution of 16 downloads and 4 upstream channels.

Positive traits:

1. Supports 4k and HD video streaming.
2. Works up to 300 internet plans.
3. Speed ​​up to 680 Mbps, 16 × 4-channel connection with DOCSIS 3.0 Gigabit Ethernet port.

Flaws:

1. The voice services included in the packages do not work well.
2. Does not work with Verizon, AT&T or CenturyLink.

ARRIS for fiber optic network

If a user uses gigabyte speeds on a fiber optic network, the Arris cm820 cable modem is the best fit for them, whether they are on a 1 Gbps network or not. This is one of the online gamers that also performs well among users who use huge data streams to download movies and games or simply need the latest technology.

Gigabyte Internet is the top of this model line. So, to enjoy all the advanced technology, you need to check with your provider whether they have fiber optic lines to provide services to your home. However, it should be noted that the maximum Internet speed will depend on the tariff plan.

Positive traits:

1. The fastest internet speeds with download speeds of up to 1.4 Gbps on fiber and 626 Mbps on cable. This is a true Arris Gigabit Cable Modem.
2. Internet speed is supported by 32 channels.
3. Is the latest DOCSIS 3.0.
4. IPv4 and IPv6 support.
5. Certified by most major ISPs.

The downside is that the LED lights are too bright and annoying.

If a person wants to enjoy all the benefits of fiber optic Internet, the ARRIS SURFboard SB6183 is the ideal modem. It is equipped the best technologies, which will help you optimize your gigabit subscription, but the main selling point is that it comes with a price tag under $100.

• CPU - P4, 3GHz or faster.
• RAM - 1 GB or more.
• Hard drive - 7200 rpm or faster.
• Ethernet - thousand BaseT).
• Windows.
• Ethernet connection- Windows 2000, Windows XP, Windows Vista or Windows 7 MacOS.
• Ethernet connection - System 7.5 to MacOS 9.2 (Open Transport recommended) or Mac OS X,Linux/other Unix.
• Ethernet connection - hardware drivers. Computers that do not meet this configuration will be able to run the CM820, but will not use its maximum throughput.

Budget model D-Link DCM-301

D-Link DCM-301 is the most affordable budget cable modem for home networks. In particular, it provides good speed and a simple design that works easily in a custom network setup. Plus, it's easy to pair with a cloud router or connect to a storage device for networking needs. So among all the others in this range this is the best choice modem

Positive traits:

1. Cheap and reliable for a $50 cost.
2. Uses DOCIS 3.0 technology, which is 8 times faster than DOCSIS 2.0.
3. Compatible with most Internet providers.
4. Easy setup.
5. Small design and doesn't take up too much space.
6. Available Internet speed taking into account its price: 343 Mbit/s.

Disadvantages: Some inconsistency in the connection, which is easily resolved with a quick reset.

Smart MG7550. If a user wants a small network layout, they will probably prefer a router. Since there is not always free space for cables and two separate devices, this circumstance makes the modem-router combo good option. It is a good choice for the best router combination, has reliable network quality and supports gigabyte internet. The combined technologies of this device provide maximum WI-FI speed and provide streaming capabilities just like a Cisco cable modem.

Positive traits:

1. Compatible with most major internet service providers, including Comcast, XFINITY, Time Warner Cable, Cox and Charter Spectrum.
2. Fast and reliable speeds up to 686 Mbps 4 Gigabit Etherport supporting over fast internet.
3. Easy to set up.

Disadvantages: The boost feature, which is supposed to provide a wireless signal anywhere in the home, often doesn't meet customer expectations.

Using the modem/router command has its advantages.

So while the Motorola Smart MG7550 with AC1900 may be a little pricey, it offers better transfer speeds and would still be ideal for a small apartment, home or office. Plus, this networking solution is great for gaming and streaming.

The first version of the standard, DOCSIS 1.0, ratified by Cable Labs in 1999, had rather limited capabilities. Let us recall that DOCSIS is a data transmission network superimposed on the HFC network.

The first version of DOCSIS 1.0 had a reverse channel transmission speed of no more than 5 Mbit/s, and the ability to manage service parameters was limited to setting upper and lower limits on the channel width allocated to one subscriber and fixing the maximum volume of data sent at a time. In addition, the standard included the 6 MHz band used in the United States, which is not optimal for European operators. The last problem was solved by adding European modifications to the standard, providing for the possibility of using the 7 and 8 MHz bands.

The functionality of the standard was expanded in later versions. DOCSIS 1.1 introduced QoS mechanisms, allowing, in particular, the launch of voice services on the network. At the same time, the security system was improved and some additional mechanisms were introduced to increase the efficiency of using the strip. And finally, the return channel bandwidth was doubled.

In DOCSIS 2.0, the throughput of the reverse channel has become three times larger and reached 30 Mbit/s. This version added high-speed QAM modulation schemes and an S-CDMA multiplexing system for the return channel. The throughput of the forward channel remained at 47 Mbit/s (55 Mbit/s for the EuroDOCSIS version). As a result, the DOCSIS network has become more suitable for symmetric services. New multiplexing systems in combination with enhanced noise protection circuits have made it possible to reduce the minimum required C/N level at the input of the return channel receiver from 23 dB to 12 dB. DOCSIS 2.0 also introduced VLAN support.

DOCSIS 3.0.

The main goal of developing this version is to increase the throughput of DOCSIS channels.

This need is driven by the explosion of P2P applications involving the transfer of heavy video files, as well as plans to use DOCSIS networks to provide Video on Demand (VOD). The problem of sharply increasing the capacity of DOCSIS channels could only be solved in an “extensive” way, that is, by increasing their width. Previous versions of DOCSIS allow the use of multiple forward and return channels, the number of which is limited only by the width of the available spectrum. But these channels work independently of each other. This excludes the possibility of their simultaneous use by one subscriber, not to mention one application. Due to the inability to flexibly redistribute the load, the spectrum is not used optimally, and some “heavy” applications, such as VOD, quickly block the channel.

Thus, it was clear that expansion had to be done by expanding the channels themselves. This problem can be solved in two ways. One of them, proposed by Cisco and Broadcom, provides for linking at the level of MPEG-2 TS transport streams. MPEG-2 TS is a transport format for DVB networks, which is used, in particular, for transmitting Ethernet data packets in DOCSIS channels. The dimensions of the transport stream are limited by the width of the physical channel of the cable network, determined by the standard frequency plan. For America this width is 6 MHz, and for Europe 7 or 8 MHz. Combining multiple traffic streams into one would essentially mean expanding the bandwidth of one physical channel, which would entail recalculating the entire network to meet noise and intermodulation distortion conditions.

Therefore, CableLabs preferred the second option proposed by Arris and Motorola. It provides for maintaining the width of physical channels, but with the possibility of linking them into one logical channel. In this case, a separate transport stream is formed on each physical channel, but packets related to one service can be distributed over several channels. This option uses the transport lane somewhat less efficiently, but it is also less expensive in terms of implementation.

The standard defines the minimum number of physical channels that DOCSIS 3.0 equipment must support. In both the forward and reverse channels, a combination of at least 4 physical channels must be supported, and IP packets related to one service can be randomly distributed over all physical channels included in the logical association. Such a network will allow transmitting up to 160 Mbit/s in forward channel (EuroDOCSIS) and up to 120 Mbit/s in the reverse. The maximum number of channels is not explicitly limited, but the forward direction requires that all associated channels be located in the 60 MHz band. This is due to the difficulties of implementing a broadband receiver in a cable modem. The number of direct channels placed in this band does not exceed seven for the 8 MHz band and ten for the 6 MHz band.

The 60 MHz frequency segment itself can be located anywhere in the terrestrial range, the upper limit of which is raised to 1002 MHz. The upward shift is dictated by the spread of passive and active components in the United States distribution network, operating in the band up to 1000 MHz, although the operating band of the bulk of existing networks is still limited to 862 MHz. The standard does not impose other restrictions on the frequency placement of channels, although they may be dictated by the state of the spectrum or the characteristics of the modulators.

The maximum bandwidth of one return channel is still limited to 6.4 MHz, which allows transmission of up to 30 Mbit/s. But the cable modem must support the ability to simultaneously transmit on at least 4 channels. When it is necessary to go online with a specific application, the cable modem sends a request to the CMTS, which allocates slots within one or more channels for this purpose. The maximum number of channels that the modem can operate is reported to the CMTS during authorization.

The second feature of DOCSIS 3.0 compared to its predecessors is IPv6 support. It significantly expands the range of available addresses, which may soon prove useful for administration purposes, and in the future for assigning to subscribers.

Third innovation - support for multicast transmission. All information about the characteristics of multicast traffic is located on the CMTS, which allows you to support advanced multicast group management mechanisms.

In addition, the new standard introduced the ability to bind multicast services not to the modem, but to the CPE(Customer Premises Equipment), connected to the local network of the modem. Mechanisms for delivering multicast traffic can be supported for them and a specific QoS can be assigned. The latter function obviously requires QoS to be observed in the network behind the cable modem as well.

The standard also includes additional mechanism for prioritizing multicast traffic, for this purpose, the concept of a group service flow (Group Service Flow) is introduced, which can refer to a service class (Service Class Name) within which a given set of QoS mechanisms is implemented.

CMTS introduced proxy support for TFTP (Trivial File Transfer Protocol) server, which allows you to speed up the loading of configuration files while connecting large quantity modems.

An important point is to increase transmission security. In DOCSIS 3.0 appeared ability to encrypt modem traffic using AES(Advanced Encryption Standard) algorithm using 128-bit keys. The security management functions themselves have been expanded, verification of the sender's IP address has been introduced, the ability to securely load software and a number of other improvements have appeared.

It should also be said that the expansion of functions, and, most importantly, the emergence of the concept of modular CMTS, which is discussed in the next paragraph, is significant complicated the OSS operational support system(Operations Support System). The number of MIBs used by this system, running on the SNMP protocol, has increased from 1385 (DOCSIS 2.0) to 2130. Moreover, in terms of network monitoring, backward compatibility of systems is not observed.

Modular CMTS

Simultaneously with DOCSIS 3.0, the concept of modular CMTS was introduced. Its main idea is that the generation of RF signals is transferred from the CMTS to a separate Edge-QAM device. Such devices have existed for several years and are installed at the border of the IP/Ethernet digital transport network and the DVB-C access network. M-CMTS Core in this scheme retains the functions of distribution and synchronization of DOCSIS packets, packet classification, quality of service management and security.

This division is primarily due to the fact that the access segment in modern networks is increasingly closer to the subscriber. In the case of an integrated CMTS architecture, they must be installed at each gateway at the edge of the transport network and the access segment, and the closer the transport comes to the subscriber, the more CMTS will have to be installed. The modular architecture allows you to use one CMTS located at the central station, and install Edge-QAM devices at the edge of the transport network. These devices can simultaneously be used to convert TV streams. The idea of ​​separating RF interfaces has so far been implemented only for the forward channel; reverse channel stream receivers continue to be integrated with CMTS, which reduces the value of this modular solution. The price for the flexibility of the architecture was the appearance of additional servers coordinating the work of distributed components.

The block diagram of a modular CMTS is shown in the figure:

In addition to CMTS-Core and Edge-QAM, it includes a DOCSIS Timing Server that synchronizes them working together, as well as the Edge Resource Manager, which coordinates the distribution of Edge-QAM transport resources in accordance with requests from the headend service subsystems.

CMTS-C and Edge-QAM are connected via the GBE channel using the DEPI (Downstream External Physical Interface) interface specially developed for this purpose. The distance between them is limited only by the DVB / MPEG requirements for the relative packet delay. The DTI interface was developed for the interaction of M-CMTS with the DOCSIS Timing Server, and the ERMI interface was developed for interaction with the Edge Resource Manager.

DOCSIS 3.0 can also be implemented in integrated CMTS (I-CMTS), which have a traditional architecture. Moreover, the first implementations of Pre-DOCSIS 3.0 equipment were implemented precisely on the basis of traditional architecture.

Specifications.

Descriptions of the characteristics of DOCSIS 3.0 are collected in four documents and one technical report, available on the Cable Labs website.

• The MULPI (Media Access Control and Upper Layer Protocols Interface) specification defines the order of linking forward and reverse channels, compatibility with IPv6 addressing and its coexistence with IPv4, the transfer of multicast information from cable modems to CMTS, and a standardized mechanism for providing QoS for multicast sessions.
• The PHY (Physical Layer Specification) specification provides a typical system architecture and also outlines the principles of generation and processing of DOCSIS signals.
• The SEC (Security Specification) defines the principles of encryption and key administration when closing transmitted data with the AES algorithm.
• In addition to link bonding, IPv6, multicast and enhanced security, the OSSI (Operations Support System Interface Specification) details the principles of receiving multiple return channels on one port, methods for upgrading the network topology to implement DOCSIS 3.0, as well as improved diagnostic methods and signal quality monitoring , collection of network operational parameters and application of billing.
• The MGMT-3 DIFF (DOCSIS3.0 Management Features Differences) technical report summarizes the differences between DOCSIS 2.0 and DOCSIS 3.0 network management systems.

State of the market.

Thus, the standard offers many new features that vary in complexity and implementation urgency. So, for example, a combination of forward channels is easier to implement than a combination of reverse ones. At the same time, due to the asymmetric nature of most “heavy” applications, a combination of direct channels is more relevant today. Therefore, it is no coincidence that the combination of forward channels in CMTSs was implemented two years earlier than the combination of reverse ones.

To make it easier and faster for certified devices to come to market, Cable Labs has established three stages for qualifying CMTS with DOCSIS 3.0 support. Depending on the degree of completeness, they are called gold, silver and bronze. Gold, or full certification, is awarded to a CMTS that meets all specification requirements. The full list of requirements of the lower two levels is provided only to manufacturers of certified equipment, but, judging by press releases from Cable Labs, bronze qualification is assigned to equipment if it provides a combination of 4 channels in forward direction, and the silver one, if in addition to this it can link back channels, supports AES encryption and IPv6 addressing.

During the 56th wave of certification, which took place in December 2007, not a single device received full certification. CMTS Arris C4 and Cisco uBR10012 received bronze qualification, and CMTS Casa Systems C 2200 received silver qualification. In the coming days, the results of the next, 57th wave of certification should become known.

As for modems, only full certification is provided for them, which requires them to be tested together with a fully qualified CMTS. Therefore, there are no certified models yet and their appearance in the 57th wave is unlikely. Manufacturers now offer modems compatible with their own models CMTS. So at the end of February, Motorola announced a new line of Surf Board DOCSIS 3.0 cable modems working in conjunction with the BSR 64000, and Arris and Cisco, whose CMTS received bronze qualification, offer modems of the “2.0V” format that support a bunch of direct channels.

Implementation.

In the USA, the birthplace of the standard, operators are in no hurry to commercially implement these solutions, limiting themselves to laboratory tests and small-scale field trials. At the same time, in other markets there are already cases of implementation of DOCSIS systems with support for channel bundles. Thus, the Singapore Starhub network implements a pre-DOCSIS 3.0 system with a combination of three channels, allowing the transmission of streams up to 100 Mbit/s, using CMTS and Motorola subscriber modems. And the Canadian Videotron network also launched a system with a combination of three channels.

So! Subtleties of buying a router:

If you're looking for the best Internet speeds for your home, cable Internet service is still a good choice for most users. But what most users don't know is that they sometimes pay much more than they should for cable broadband—especially if they use equipment offered by the cable company.

Indeed, many users can save up to $5 a month—that's more than $60 a year—on their current cable Internet connection. To this end, I have compiled the five most popular questions from readers that I usually receive on the subject. cable Internet. I've included both short and long answers to each question, including suggestions for how to save money on your monthly bill (spoiler alert: buy, don't lease, your cable modem).

What Cable Modem Do You Really Need?

Short answer:
choose one that can support the speed of the tariff plan you subscribed to. When in doubt, choose one that supports DOCSIS 3.0. Of these, you should choose not the most expensive one, and to be sure, from the list of supported equipment of your provider.

Note: Your actual Internet connection speed depends on the speed of your modem, router, Wi-Fi connection, switches, and the user device itself, and by the way, on the tariff plan you have chosen. Most of the time, what you pay for is the lowest common denominator, and does not determine the actual speed of your Internet connection.

Long answer:
A cable modem is a device that receives an Internet signal from a cable provider and turns it into a data signal that computing devices such as personal computers, tablets, or smartphones can understand. The modem comes with a female coaxial connector - just like the one behind your HDTV - and a LAN port. This means that with a modem, you can only connect one computer to the Internet. To connect more devices, you will need to get a Wi-Fi router. (More on this below.)

Modems are usually very simple devices, and because of this, most of them are practically indistinguishable from each other. The biggest difference between them is the standard they support, which determines the internet speeds it is capable of supporting, both for downloading and uploading. This standard is called d ata over cable service interface specification, or DOCSIS.

Currently on the market there are DOCSIS 1.x, DOCSIS 2.0 and DOCSIS 3.0 modems. Both DOCSIS 1.x (basically a now obsolete standard) and DOCSIS 2.0 support only one channel, which supports download speeds of 43 Mbit/s and upload speeds of 10 Mbit/s and 31 Mbit/s, respectively.

In DOCSIS 3.0 (which is backwards compatible with older standards), single-channel speeds remain 43 Mbit/s download and 31 Mbit/s upload, but modems are now capable of processing multiple channels (channel bonding) at a time. A typical DOCSIS 3.0 modem typically offers four or eight download channels, resulting in speeds of 172 Mbps or 344 Mbps, respectively. For upload, they typically support four channels, offering speeds of up to 124 Mbps. DOCSIS 3.0 modems will appear relatively soon, which can handle even more channels.

Your actual Internet speed also depends on what you pay for; the faster you want, the higher the monthly payment. If you pay for an Internet plan with a download speed of 30 Mbps or less, there is a chance that you will need a DOCSIS 2.0 modem, which costs almost half the price of a DOCSIS 3.0. Moreover, if your tariff is called: Lightweight, Basic, Starter or Standard, then a DOCSIS 2.0 modem will probably be enough for you, but if you choose more high level, such as: Turbo, Premier, Super or Extreme, then a DOCSIS 3.0 modem with four or even eight download channels is a must.

Please note that all broadband services offer much slower upload speeds than download speeds. Most of the time, most tariff plans They offer upload speeds of only 10 Mbps. In addition, you need to check whether the modem supports the DOCSIS standard and is on the ISP's list of approved modems, otherwise it may not work at all. In addition, sometimes you come across one ISP that does not allow the use of consumer modems on its network.

On a typical home network, you need to connect the modem to the WAN port Wi-Fi router using (preferably) a short network cable.

Rent or buy?

Short answer:
Whenever possible, it is better to purchase your own modem. This is a good saving over time.

Long answer:
When you register a request to connect to a cable Internet service, the provider often includes a modem in the service package. This device is usually not free; it costs you monthly rent. Often, the provider does not clearly inform you about this when concluding a contract, and also that you can avoid this by using your own equipment. This modem rental fee may not be that high at first, but then it usually increases, sometimes up to $10 per month, which may not be entirely interesting to you.

It doesn't seem like it a large amount, but over time, this adds up to not so little. And if you plan to use the Internet for one year, it is much better to purchase your own modem, which costs between $50 and $100, and new. You can buy one before signing the contract or any time after that. In the latter case, make sure you return the modem provided by the service providers, or else you will be charged for it. From my personal experience, it is better to bring this device and return it in person to the nearest customer service center to avoid losing it.

Even if you plan to use the Internet from this operator for a short time, it is still a good idea to purchase your own modem. You can always use it again for a new connection, as long as the connection type is the same, or sell it and get most of what you paid for it back.

Continuing the conversation about selling an old modem, you can also purchase a used one.

New, used, or returned?

Short answer:
It never hurts to buy a brand new modem, but you can also save a lot without losing anything if you buy a used one or after a return.

Long answer:
Cable modems are simple devices and after initial installation they are usually left alone and simply left in the same place. You'll never have to change settings or tweak anything again. Also, modems have no moving parts (most of them don't even have fans). Therefore, they can work for a long time and simply become obsolete before they actually stop working. This means that purchasing a brand new modem will not benefit you any more than receiving a returned modem of the same type.

In truth, the most common reasons why modems are returned are either that they are no longer needed or that they do not fit appearance interior design devices. And from the inside they are practically no different from new devices. In many cases, the modem that the Internet provider offers you may just be returned, and this device was used by previous customers. On the market, when returned, modems cost up to two-thirds of the price of a new one.

Purchasing used modems involves a higher risk associated with previous owners. If the modem has not been dropped and there is no noticeable external damage, it should work well. However, if you buy a used one, make sure that you can return it after a few days because if it can work for a few days without any problems, then there is a chance that it will work for a long time. In turn, a used modem tends to cost about a third of the price of a new one.

From my personal experience, the most common thing that breaks in a modem is the power adapter, which is quite easy to replace.

Should I buy a modem with a built-in router or two separate devices?

Short answer:
If your provider does not provide you with a free modem with a built-in router (which is unlikely), always just ask for a modem and purchase a router separately. After receiving the modem, just take one of the routers, not the most expensive one, according to your need. If you really want a combo device for practical reasons such as reducing cable clutter, the Motorola SBG6782-AC Surfboard eXtreme is your best choice for this moment. Make sure you read his full review first.

Long answer:
As mentioned above, you need a router to share the Internet connection from the cable modem on more than one computer; the total number is up to 254 devices for most routers. You just have to connect the LAN port of the modem to the WAN port of the router using a network cable. This is the preferred setup and also the most popular, as it gives you the flexibility and ability to customize your network based on your need and your budget.

There are also combo devices that consist of a modem and a router in one box. I generally don't recommend them for two main reasons. First of all, it's dangerous. If any part of the device, modem or router module, is damaged or outdated, you must replace the entire device. The second reason is that in most existing combination devices, the router portion is usually very limited, making your home network less flexible and functional than it could be.

If you run a business, try to avoid purchasing a combo device because the router portion of it likely won't have all the configuration options your business needs. Capable System Administrator You can still get everything working fine by adding another router to the network, but that's a lot more work than just purchasing a modem and the right router outright.

Do I need to purchase an extended warranty?

No, it's not worth it. Cable modems (or combination devices), even those returned, usually come with a factory warranty ranging from 90 days to two years. Since these are simple devices, if anything unusual should happen, such as a defective device or you encounter problems installing it, it will happen immediately after purchase. After this, it is unlikely that something like this will happen.

Buying an extended warranty is simply a waste of money. Instead, it's better to use that money to buy surge protection for your home network devices, since power surges and lightning are two of the most common things that damage equipment. It is also better to install the device in an open space and where it is dry to avoid damage caused by water or overheating.

Should you try to reduce the price?

Definitely!!

It is true that most of us live in an area that is served by just one cable company, but there are other alternatives such as FDDI, satellite or DSL (which is available almost everywhere and is usually cheaper). You should use them as your leverage in negotiations with the cable company for a better deal. You can also get better deals by signing up for packages with multiple services such as TV, internet and phone, although don't sign up for anything you don't plan to use.

Some cable companies may give you good terms for a period of time, for example six months, and then start charging you the full rate, which is up to 50 percent higher. You can always dial the operator or check the website when this period ends and ask about current or new promotions, or you can simply terminate the contract and then re-subscribe. It costs nothing and you already have a modem.

Most importantly, check back from time to time to see if there are new promotions or discounts, or simply call them to ask for a lower rate. It works. After all, you can't get what you didn't ask for.

That's all for now. If you still have questions, feel free to write to me at,

Even 3-4 years ago, the cable operator firmly knew that the best solution for providing a package of triple play services (television, Internet access and telephony) was a television cable network with a return channel for data transmission using DOCSIS technology. This concept of cable networks was supported by all CATV equipment manufacturers without exception, providing the opportunity to equip all active distribution equipment with passive or active return channel modules. Exactly following this concept, a huge number of large and small cable networks were built in Russia. Not all built networks actually used the reverse channel, but the potential for activating the reverse channel is available to almost any cable operator using equipment from such vendors as Teleste, Wisi, Hirschmann, Arcadan, Fuba, C-Cor, Gl, Vector and many others .

In Russia, there are examples of quite successful commercial triple play projects implemented precisely using this technology. For example, in Kostroma, many thousands of subscribers of the cable network of the Verkhnevolzhsky branch of CenterTelecom receive not only multi-program cable television and the Internet, but also telephone services using cable modems with telephone adapters. It would seem that by introducing a package of triple play services (or, more often, double play, i.e. without telephony) based on the once advanced DOCSIS 2.0 technology, the cable operator could feel quite confident in the market for many years. However, in the last 3-4 years, the market situation has been changing rapidly, and in the new conditions, the cable operator, which has a classic HFC network with a return channel, is clearly losing its position to operators with a higher technological level.

Recently, not only in Moscow and other large cities of Russia, but also in small regional and district centers, competition in the market for broadband access services has become extremely intense. If just a few years ago it was enough for operators to “capture” the most attractive territories in a timely manner and geographically divide their zones of influence, now it is quite common practice for several multi-service operators to operate in the same territory. Moreover, large companies they begin expansion or buy up regional players, hoping to quickly cover the market.

Let us briefly list the most important trends in the Russian market of broadband access services that are already taking place or are expected in the very near future:

• increased competition even in small localities;
• exit to regional markets major all-Russian players;
• massive consolidation (merger, acquisition) of operators;
• a significant increase in access speeds and quality of service provision;
• the emergence of new services (HDTV, VOD, content on demand, etc.);
• the emergence of new business models, penetration of non-mass (target) demand products and services into the television advertising market, etc.

Naturally, in the conditions of such intense competition, the best prospects are for operators who provide subscribers and corporate customers with the most advanced level of broadband access. In connection with increased modern market demands, widespread construction of MetroEthernet networks begins, providing subscribers with an unprecedented access speed of 100 Mbit/s, and large corporate customers can connect directly to the IP backbone, in which speeds range from 1 to 10 Gbit/s. Such high access speeds make it possible to provide a wide variety of previously unavailable services, for example, IPTV in high-definition format for several TVs in an apartment at once, network ultra-dynamic games and much more.

It is clear that a multiservice operator building its network “from scratch” today has good reasons to build a network using the “Optics to the Home” technology with a parallel GigabitEthernet network, physically combined in a common construction infrastructure with a television network, in other words, for each logical The network is allocated its own fiber in the main optical cable. But what situation does a cable operator find itself in today, having long ago built its broadband network based on far from outdated technologies with developed infrastructure and a return channel and having invested considerable funds in its construction? Can it provide subscribers with access speeds commensurate with what MetroEthernet operators offer? Can it deliver the latest, cutting-edge services based on extremely fast access speeds?

Having honestly answered these questions, we must state that today, in the conditions of such intense competition and the emergence of the latest advanced access services, a cable operator that has a technological base for data transmission based on the recently latest version of DOCSIS, i.e. DOCSIS 2.0 can no longer fully meet modern market requirements. Using DOCSIS technology version no higher than 2.0, deployed by most operators, it is impossible to achieve a data transfer speed of more than 55 Mbit/s for a sufficiently large group of subscribers, and realistically for one user - no more than 25 Mbit/s.

The cable operator is now beginning to acutely feel that DOCSIS 2.0 technology poses development limitations additional services, namely high-speed and ultra-high-speed Internet access, IP telephony, etc. In conditions of fierce competition with MetroEthernet operators, the cable operator is experiencing increasing difficulties, having as the main argument for the fight for subscribers no longer access speed, but more affordable rates, i.e. In any case, it reduces its income. In addition, the HFC network requires significant personnel effort to bring it to normal conditions and maintain it in working order in most cases. Thus, the cable operator, on the one hand, continues to bear significant operating expenses, and on the other hand, cannot make an adequate competitive offer.

In this situation, he actually has 2 options:

1) either look for all existing opportunities to significantly increase access speed without changing the architecture and infrastructure of the network, that is, make maximum use of the considerable reserves of DOCSIS technology, as we will see later;

2) either become an Ethernet operator, i.e. build a parallel Ethernet network and operate 2 networks at once, making significant capital investments and increasing operating expenses, which sharply reduces today's profits and pushes the payback period into the future.

Generally speaking, it is quite logical for a CATV operator to use exactly the technology that was invented by the community of large cable operators and telecommunications equipment manufacturers, namely the DOCSIS standard. The authors, frankly speaking, have never heard that, for example, COMCAST would seriously consider the issue of switching to MetroEthernet, just as, however, no one has heard that any large Ethernet provider has seriously displaced even the average cable or telephone operator in North America. Those. in the USA or, say, in Germany, the use of a technology other than DOCSIS by a cable operator, namely MetroEthernet, PON, etc., is considered unnatural. The natural approach is when the cable lies and is used until a broadband signal can be quite successfully transmitted through it.

Also, recently, operators are increasingly switching to digital television broadcasting, while using complexes to provide services that do not interact with each other in any way, except perhaps located within the same rack and using the same network. The generalized solution scheme used by the operators in this case is presented in Fig. 1.

Fig.1

So how far can a cable operator push the technological limitations of the DOCSIS 2.0 standard? The answer lies on the surface - not so long ago, thanks to the efforts of the CableLabs consortium, the newest standard appeared - DOCSIS 3.0 with its European version EuroDOCSIS 3.0, which, apparently, solves all pressing issues and, as usual, does not require construction new network. Moreover, all subscriber devices already installed at subscribers can continue to be used with new DOCSIS 3.0 stations, although they will work with them according to their previous version.

The main advantage of DOCSIS 3.0 is the ability to combine multiple frequency channels, providing much higher access speeds. When explaining the principle of operation of the new standard, they usually provide a graphic illustration showing that when several frequency channels are combined, a kind of “pipe” is formed with a much larger diameter than the “pipe” of an individual channel. Thus, combining 4 frequency channels into a downstream pipe allows you to achieve speeds of over 200 Mbit/s.

So, the most important differences between the 3rd version of DOCSIS and the 2nd are in the channel bonding of downstream and in the bonding of upstream channels. Downstream channel aggregation is the most important feature of DOCSIS 3.0 and is already supported by a number of cable modem manufacturers. Today you can purchase custom modems that support combining, for example, 3 downstream channels, i.e. today it is possible to give subscribers speeds of up to 150 Mbit/s, see fig. 2. And this is already something. This is exactly what knocks the trump cards out of the hands of the cable operator's competitors! In addition, DOCSIS 3.0 provides:

Rice. 2.

• advanced multicast functions;
• IPv6 support;
• support for improved AES encryption method;
• additional functions management.

For the capabilities of each version of DOCSIS in terms of access speed, see table. 1.

CableLabs also made innovative changes to the CMTS architecture. The new QAM standard now physically separates modulation from DOCSIS MAC. The CMTS still sits between the IP backbone and telematics services on one side, and the user modems on the other; the difference is that the downstream modulation unit is physically located separately. This concept is called M-CMTS (modular cable modem termination system), see Fig. 3, and this brings a lot of benefits.

First, it effectively reduces the cost of downstream modulation. Secondly, it is finally possible to combine digital broadcasting with IP via a single QAM. Moreover, manufacturers have a free hand to implement DVB processing options on one platform.

Currently, many manufacturers have announced that they support the new standard, but so far none of them have implemented all the features of DOCSIS 3.0, so all implementations are called “preDOCSIS 3.0”. However, the most important task - providing a much higher speed of incoming subscriber traffic (from 100 Mbit/s) compared to DOCSIS 2.0 - is successfully solved by CMTS stations in the preDOCSIS 3.0 version. Further upgrade to full version 3.0 will be produced in software. In the authors’ opinion, two US vendors have the most impressive results in terms of practical implementation of DOCSIS 3.0 systems: BigBand Networks and CASA Systems.

The first vendor, Bigband Networks, unlike all other vendors, provides support for the new standard based on its Cuda 12000 developed for DOCSIS 2.0. Thanks to the innovative MeshFlow architecture, which ensures that all traffic is processed not in the core, but distributed across station modules, which ensures non-blocking and increased reliability and availability of the entire system, the new capabilities of DOCSIS 3.0 are conceptually easily combined with the Cuda 12000 and thus make it possible to simply upgrade the software to DOCSIS 3.0, all available interface modules can be used in M-CMTS and beyond. Those who have already purchased the Cuda 12000 and installed them are especially lucky. For these operators, migration to DOCSIS 3.0 will be the easiest and most cost-effective. This is very difficult on equipment from other vendors.

Rice. 3.

The second vendor is CASA Systems, which provides extremely high downstream and upstream densities in a single unit device. In particular, a configuration such as 32 ds × 16 us is supported. Such a high density was achieved thanks to the innovative solutions used and the high engineering skill of the developers. In fact, at the moment, this is the only pizza box manufacturer for DOCSIS 3.0. What sets this platform apart is that it is used for DOCSIS, DVB, and IPTV. This is such a universal solution that it is difficult to find an analogue for it. Most likely, this will be a whole rack with various telecommunications equipment, as well as many software solutions. This solution is truly unique in that operators who choose to build MetroEthernet networks can use such a device subsequently, after a complete transition to Ethernet, as a scrambler and QAM modulator for DVB broadcasting. It should be noted that, unlike many others, the two mentioned manufacturers are not limited to declarations of readiness to release CMTS DOCSIS 3.0 in some happy future, but are already actually placing orders for the production of such CMTS.

For example, BigBand Networks is currently supplying and installing a modular M-CMTS headend to a large cable operator Multikabel (Holland), which is the first company in the world to practically deploy a data network based on DOCSIS 3.0. At the same time, CASA Systems offers the market a ready-to-ship flexible and efficient solution that provides DOCSIS functionality, as well as QAM modulation together with PSI/SI processing, CAS Symulcrypt support, etc. on one compact 1U platform!!! Thanks to this solution, the operator can purchase one platform for both tasks, and also flexibly adjust the bandwidth for services as needed.

Now the implementation of IPTV through this platform, incl. and through DOCSIS, absolutely real. This, for example, applies to a service such as “video on demand”, the bandwidth for which can be allocated in QAM. The deployment of the M-CMTS platform makes it possible to more effectively use UEQ (universal edge QAM). To receive the new benefits of DOCSIS 3.0, you must purchase a new modem. Not every user will want to pay for this. This is easiest for a small business to do, for which the price of the issue is small compared to the new opportunities, while most subscribers will weigh and think for a long time. However, the technology allows cable operators to move with the times and more effectively fend off competitive pressure. For example, M-CMTS produced by BigBand Networks and CMTS C2200 manufactured by CASA Systems allow cable operators to offer access speeds of over 100 Mbit/s on a single chassis to subscribers with DOCSIS 3.0 modems and speeds of about 25 Mbit/s to those with current generation modems.

The deployment of the M-CMTS architecture, as the initial stage of the strategy towards DOCSIS 3.0, allows cable operators to grow according to market needs - to add capacity and functionality according to demand.

Thus, the new standard gives cable operators the opportunity to develop the DOCSIS standard, offer high-speed access over 100 Mbit/s based on it now, successfully compete in the access services market, and offer a range of services that require wide bandwidth, incl. DVB and IPTV on the same platform using the flexible M-CMTS architecture. By purchasing solutions now based on the preliminary version of preDOCSIS 3.0, in the future, without replacing the hardware, the operator can move to the finished DOCSIS 3.0 standard, only by changing software. This allows you to effectively protect the investments made in the construction of the HFC network.

In our opinion, only with the advent of the third version of DOCSIS did this technology make a truly strong leap forward, ensuring the introduction of new high-speed services; previous versions only tried to adapt CATV networks for Internet access, using its resources 5 percent in the same way as a person uses a tiny part of his brain's capabilities. DOCSIS 3.0 allows you to use the CATV network to its full capacity.

The Internet is transmitted via telephone, television, fiber optic cables and twisted pair cables. The choice depends on the existing network infrastructure and financial feasibility. Each option has its own data transfer standard.DOCSIS is one of the standards. In accordance with it, data transmission is carried out through deployed television (coaxial) cables. Often you will see a digital value next to the standard. It indicates the version of the technology specification. The versions differ from each other in terms of network organization, and for the user the main difference is in the Internet speed.

DOCSIS connection technology

The standard for connecting subscribers to the network via coaxial cable uses a downstream channel, that is, it is carried out from top to bottom.

In general terms, the scheme looks like this:

where CMTS is the cable modem terminal system. Simply put, this is the operator’s modem with which user devices connect. It encodes and moderates data streams, transferring them to the desired frequency range.

This scheme involves distributing the Internet through the main modem, CMTS, to all connected subscribers simultaneously.

When did the DOCSIS standard appear and who is it useful for?

Doxis began to be used in 1998. The purpose of the standard is to unify the requirements for data transmission over coaxial cable and guarantee the compatibility of equipment supplied by different manufacturers.

At the time of implementation, the technology was promising. It made it possible to conduct the Internet through existing networks, which means reducing the costs of creating new infrastructure. For cable television operators, this meant the possibility of expanding the list of services provided, and for users - inexpensive Internet with a fairly high speed.

Nowadays, connection via DOCSIS is inferior in speed to other network connection options - FTTB, PON, HCNA.

What are the different types of Doxis technology?

Doxis is divided by type of specification. The division is carried out in the order in which updates with additional functions were released:

• Version 1.0.
• Version 1.1.
• Version 2.0.
• Version 3.0.
• Version 3.1.
• Version 3.1 FD.
• EuroDOCSIS.

The differences between types are determined by quality of service (QoS) criteria, flow capacity, modulations, and noise immunity. EuroDOCSIS – adaptation of the standard to the European frequency grid.

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What is the speed of Doxis

The very first standard assumed data transmission at a speed of no more than 42 Mbit/s, and in the opposite direction - up to 10 Mbit/s.

Channel asymmetry also existed in subsequent years when updates were released. Only in the latest version of the specification was it possible to equalize the speed of flows.

Starting with DOCSIS 3.0, the data transfer speed was increased to 170 Mbit/s on the forward channel and up to 122 Mbit/s on the reverse channel.

The regulations of version 3.1 specify the speed of the forward channel up to 10 Gbit/s, and the reverse channel up to 1 Gbit/s. These values ​​significantly exceed previous specifications. In addition, the standard provides for reducing energy intensity through energy management tools. This approach makes the coaxial cable transmission industry more economical.