Actually, many have heard the abbreviation DOCSIS, but not everyone understands what it is and why it is needed. The most curious could even be enlightened by this issue on Wikipedia, but as practice shows, quite a lot of questions still remain. So, we begin to tear off the covers, let's deal with the questions:
1. what is it?
2. who needs it?
3. what is needed for this?
4. how to start?

The faint of heart who do not want to delve into "How it" s made? please do not look under habrakat - there is nothing interesting there.

So let's start with the general theory.
The abbreviation DOCSIS (Data Over Cable Service Interface Specifications) denotes the standard for data transmission over a television cable, which was adopted in 98. This standard in the original assumes data transfer up to 42/38 Mbps downstream (to the user) and up to 10/9 Mbps upstream (from the user).
When faced with technology for the first time, the question often arises - is it for everyone? No - the strip is divided into all users hanging on these DS / US.

Actually there are several versions of DOCSIS:
- DOCSIS 1.0
- DOCSIS 1.1
- DOCSIS 2.0
- DOCSIS 3.0
- EURODOCSIS
Without going into details, the differences between them come down to QoS, frequencies, link aggregation, bandwidth, and modulations. Actually, all this is directly related to speeds and viability in noisy networks.

Who needs it?
Need it first existing cable TV operators to expand the range of services by providing end users with high-speed Internet access and related attachments (VoIP, IPTV, or whatever your imagination is enough for).
I highlighted the word "existing" and because of the following (obvious consideration, I think).

Deploying a coaxial network just for the sake of providing Internet access to users from scratch is at least stupid and not economically feasible, since there are much cheaper and faster technologies (for example, FTTB, ADSL, PON). As an example, if you are not a cable TV operator, but let's say an automatic telephone exchange, then again, building a coaxial network throughout the city does not seem to be useful, it is much cheaper to go to ADSL - I think it's understandable.

With the existing well-built coaxial network covering a significant area, DOCSIS can be an optimal start, requiring minimal intervention in physics. Especially in sparsely populated areas such as the private sector, where the density of plugging couplings / switches / boxes per unit of consumer can be cosmic in the case of FTTB. Again, in the case of multi-storey buildings (the so-called residential areas) with existing competition in the form of "home networks", it may make sense to deploy a parallel coaxial FTTB network, or since you really want to use HCNA - it will be cheaper and more promising IMHO.

Equipment
In general, a typical scheme would look like this:

Actually, from the googled picture, it immediately becomes clear that in order to provide the Internet to the end user, you need:
1. a cloud in which the Internet lives;)
2. server with DHCP, TFTP services installed
3.CMTS (Cable Modem Termination System)
4. coaxial network going to the subscriber
5. modem and desire to connect to the user

Let's briefly go over the points above.
1. everything is clear with the Internet - let's say we have it
2. We will use the server on something that the administrator is familiar with. Let's assume he's familiar with FreeBSD/Linux ;)
3. CMTS… there are different black ones, dirty white ones. You can get acquainted with a short list of manufacturers.
4. The main requirement for the network is serviceability and the presence of a reverse channel on amplifiers. Serviceability is a permanent cutting out of illegal immigrants and monitoring signal levels in the forward and reverse channels. Seasonal signal fluctuations can significantly spoil the lives of users and your support team.
5. A short list of modem manufacturers can be found. The Docsis modem is a rather specific device that provides quite a wide range of possibilities - from limiting the subscriber's bandwidth directly on his modem to filters (roughly remotely controlled firewall).

Where to begin?
Recently, admins whose bosses have been knocking on me with enviable regularity, guided by the considerations set forth in “Who needs this?” bought a CMTS (for some reason, most often it is something like a used BSR1000, BSR2000, CiscoUBR) and said "shove the Internet into a cable TV network."
For people already familiar with Ethernet or ADSL, the scheme of operation of a DOCSIS network may not be entirely transparent, and the number of gestures necessary for at least one modem to ping is completely stubborn. It is quite difficult to do something without presenting the general principles of how it should work. The first thought that comes to mind is to screw the modem directly to the CMTS and see what happens. Naturally, nothing will turn out - the modem will simply flicker light bulbs with light and music and that's it. Nothing else will happen.

When trying to connect, the modem scans the entire frequency range for the presence of downstream / upstream, and if it finds it, it tries to get an address via DHCP for the modem, if the address is received, the modem tries to get a specially assembled config for itself via TFTP, after which if the config is normally chewed, it tries to get DHCP address for CPE (customer-provided equipment) which will most likely be a network card or router.

It should work normally on a test bench like this:
1. CMTS configured
2. The above services are up on the server
3. The modem is connected through a pack of taps to ensure nominal signal levels for DS/US.

1. We will not particularly focus on setting up the CMTS, because depending on the manufacturer, the physical realities of the network and the planned network topology, it will vary greatly. I am glad that there is a comprehensive documentation that came with all the devices that fell into my hands - I think it should be more or less clear for people familiar with the cisco-like interface and the general theory of configuring network devices.

The minimum hand passes that should be made over the CMTS to make it ready for bench testing are as follows:
- prescribe the DS frequency
- prescribe frequencies and modulations for US
- prescribe the address of the DHCP server that we will relay
- write secret key for configs
- write passwords
- save

2. We raise the services we need on the server.

# cd /usr/ports/net/isc-dhcp31-server/ && make install (building with Option82 support)
tftpd most likely we have by default, just uncomment it in /etc/inetd.conf
#cd /usr/ports/net-mgmt/docsis && make install
Which we need to generate binary configs for DOCSIS-compatible modems, as pkg-descr says.

Let's say we configured the CMTS as 10.10.10.9 relaying DHCP requests to our network host with IP 10.10.10.10 which looks at the CMTS. Then our /usr/local/etc/dhcpd.conf should look like this
option domain-name "catv";
option domain-name-servers 10.10.10.10;
default-lease-time 3600;
max-lease-time 43200;
authoritative;
ddns-update-style none;
log facility local7;
one-lease-per-client true;
deny duplicates;

Subnet 10.10.200.0 netmask 255.255.248.0 (
default-lease-time 3600;
max-lease-time 86400;
option domain-name-servers 10.10.10.10;

option routers 10.10.200.1;

Include "/usr/local/etc/users_dhcp.conf";
}

Subnet 10.10.100.0 netmask 255.255.248.0 (
default-lease-time 3600;
option subnet-mask 255.255.248.0;
option routers 10.10.100.1;
server-name "10.10.10.10";
option tftp-server-name "10.10.10.10";
option bootfile-name "cm_config/other.b";
next-server 10.10.10.10;
filename "cm_config/other.b";
option time-servers 10.10.10.10;
option time-offset 2;

Include "/usr/local/etc/modems_dhcp.conf";

From which it should be clear that we reserve the 10.10.100/21 network for modems and the 10.10.200/21 network for user CPEs

For ease of work in the future, we will include hosts for subnets from /usr/local/etc/modems_dhcp.conf and /usr/local/etc/users_dhcp.conf respectively. To begin with, in /usr/local/etc/modems_dhcp.conf we enter our test modem in the form

Host m1002(
hardware ethernet 00:ff:ff:55:ff:f2;
fixed-address 10.10.100.3;
filename "cm_config/testmodem.b";
}

And in /usr/local/etc/users_dhcp.conf we add our test host:

Host m10102002 (
hardware ethernet 00:cc:cc:99:aa:ff;
fixed-address 10.10.200.2;
}

The filename directive should imply that it contains the path (relative to tftp root which is usually in /tftpboot) to the binary modem config. In the simplest case, the modem config (not suitable for real use! For testing purposes only! Achtung!) will look like this:

#cat /tftpboot/cm_source/testing

main(
Network Access 1;

GlobalPrivacyEnable 0;
UsServiceFlow
{
UsServiceFlowRef 200;
QosParamSetType 7;
MaxRateSustained 0;
Scheduling Type 2;
}
DsServiceFlow
{
DsServiceFlowRef 100;
QosParamSetType 7;
TrafficPriority 3;
MaxRateSustained 0;
}

MaxCPE 16;
}

Now we should compile it into a form acceptable for the modem using the previously assembled docsis utility using the secret-key specified on the CMTS

#echo "sosecret" > /somewhere/key
#docsis -e /tftpboot/cm_source/testing /somewhere/key /tftpboot/cm_config/testing.b

We register routes for modem networks and users on CMTS in rc.conf:

static_routes="cable modems"
route_cable="10.10.200.0/21 10.10.10.9"
route_modem="10.10.100.0/21 10.10.10.9"

3. We assemble a structure from matches and acorns of pigtails and taps that combines DS and one of the US and ensures that the signal levels specified in the documentation pass to the modem.

If we did everything correctly, then on the CMTS in
bsr#show cable modem

We will see something like
Cable 0/0/D0/U0/C0 431 online 1458 26.0 10.10.100.3 00ff.ff55.fff2

And, accordingly, our test modem and test host, which, as we remember, 10.10.100.3 and 10.10.200.2, should ping.

See how simple and clear everything is? - and you were afraid. =)

In the case of segmenting the network into multiple CMTS to provide increased resiliency and performance, things look the same. And it comes down to the separation of different networks according to receptions.

The above config is not adequate for real use for a number of reasons:

Least:
- no filters for isolating users
- there are no registered snmp for collecting statistics
- there is no modem binding to a specific CPE
It would also be nice to do:
- channel shaping directly on the device
- take into account the features of various devices
- cut off the web face of the modem, the user has nothing to do there
- correctly build QoS

Initially, I really wanted to write a step-by-step manual on how to make not just “the Internet go”, but also on how to competently sell them to end users, in fact, with examples of configs, ready-made ACP, etc. But since I'm not a writer, to be honest, I'm just ashamed to show my bydlock code, which is also quite narrowly specific and in any case requires deep fine-tuning for a specific operator :)
In general terms, the requirements for billing working in a DOCSIS network are very simple:
- be able to count traffic
- be able to count money
- make flexible tariffs from the calculated traffic money
- flexibly limit custom bandwidth
- be able to compile configs for modems on the fly for each user + edit dhcpd hosts.

If everything is clear with the first four points - and in fact all ACPs are mainly involved in them, then the last one should focus on the last one. Naturally, you can issue one config for everyone, and then authenticate the user using the internal ACP mechanisms (motley authorizers) or, say, using the PPtP tunnel method, but I consider this just an additional crutch and a conscious rejection of the very convenient features provided by technology.

I think now many, many people will say that the technology is dead, expensive, not relevant and poke me in the face in FTTB, PON, HCNA. Yes, I am aware that there are such and that, for example, in densely populated high-rise buildings, the price / speed of the port is much cheaper with FTTB and that HCNA provides much more delicious speeds over the same coax with a comparable cost of subscriber hardware and no need to purchase relatively expensive CMTS. If interested, I can explain on my fingers why FTTB in the private sector is expensive, and why HCNA in the same place is reduced to “almost FTTB” in terms of the cost of the port, and also why the public is not yet ready for PON. Again, for any technology that is still alive, there are always motives from “let's use the existing network” to “otherwise it will be too expensive and time consuming”. Again, the choice to play dumping and race with the speeds of home networks is not the best option with the above performance characteristics and the DOCSIS provider's own trump card should be, IMHO, the services provided over a single cable and their quality.
At this stage of development, DOCSIS 2.0 can compete more successfully with ADSL, and 3.0 is advancing on the heels of the rest as a promising platform for Triple Play.

As always at the end of the article, I use my weak excuse sounding like:

“Yes, I am not literate, I know. The language is not native, they were not taught at school, although I guess this is a weak excuse. If you take the missing comma as a personal insult, I apologize in advance. Honestly, I didn't want to

It usually works ;)

The article was written by special order of the journal

The Internet is transmitted over telephone, television, fiber optic cables and twisted pair. 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, next to the standard, you can see a numerical value. It denotes the version of the technology specification. Between themselves, the versions differ in the features of network organization, and for the user, the main difference is in the speed of the Internet.

DOCSIS connection technology

The standard for connecting subscribers to a network via a 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 terminating system. Simply put, this is the operator's modem to which user devices are connected. It encodes and moderates data streams, translating them into the desired frequency range.

Such a scheme involves the distribution of the Internet through the main modem, CMTS, to all connected subscribers at the same time.

When did the DOCSIS standard appear and to whom is it useful

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

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

What are the varieties of Doxis technology

Docsis is divided into types of specifications. The division is carried out in order of release of updates with additional functions:

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

The differences between the types are determined by the quality of service (QoS) criteria, stream capacity, modulations, and noise immunity. EuroDOCSIS is an 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 transfer at a speed of no more than 42 Mbps, and in the opposite direction - up to 10 Mbps.

The asymmetry of the channel existed in subsequent years, with the release of updates. Only in the latest version of the specification was it possible to equalize the speed of the streams.

Starting with DOCSIS 3.0, the data rate has been increased to 170 Mbps on the forward link and up to 122 Mbps on the reverse link.

The version 3.1 regulation specifies the forward channel speed up to 10 Gbps, and the reverse channel speed up to 1 Gbps. These values ​​significantly exceed previous specifications. In addition, the standard provides for the reduction of energy intensity through energy management tools. This approach makes the industry of data transmission over coaxial cables more economical.

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

The first version of DOCSIS 1.0 had a transmission rate in the reverse channel of no more than 5 Mbps, and the ability to control service parameters was limited to setting the upper and lower limits of the channel width allocated to one subscriber, and fixing the maximum amount of data sent at a time. In addition, the 6 MHz band used in the USA, which is not optimal for European operators, was included in the standard. The latter 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 has been extended in later versions. QoS mechanisms appeared in DOCSIS 1.1, which, in particular, allow launching voice services on the network. At the same time, the security system has been improved and some additional mechanisms have been introduced to increase the efficiency of the use of the band. And, finally, the reverse channel bandwidth was doubled.

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

DOCSIS 3.0.

The main goal of developing this version is to increase the bandwidth 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 a sharp increase in the bandwidth of DOCSIS channels could only be solved in an "extensive" way, that is, by increasing their width. Former versions of DOCSIS allow multiple forward and reverse links, limited only by 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 impossibility of flexible redistribution of the load, the spectrum is not optimally used, and some "heavy" applications, such as VOD, quickly block the channel.

Thus, it was clear that the 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 a bundle 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 packets with data 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 several transport 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 the preservation of the width of physical channels, but with the possibility of their bundle into one logical channel. In this case, a separate transport stream is formed in each physical channel, but packets related to one service can be distributed over several channels. With this option, the transport lane is somewhat less efficiently used, but it is also less costly in terms of implementation.

The standard defines the minimum number of physical links that DOCSIS 3.0 equipment must support bonding. Both in the forward and in the reverse channel, a bundle of at least 4 physical channels must be supported, and IP packets related to one service can be arbitrarily distributed over all physical channels included in the logical combination. Such a network will allow transmitting up to 160 Mbps in the forward channel (EuroDOCSIS) and up to 120 Mbps in the reverse. The maximum number of channels is not explicitly limited, but for the forward direction there is a requirement that all associated channels be placed in the 60 MHz band. It is due to the complexity of implementing a wideband receiver in a cable modem. The number of direct channels placed in this band does not exceed seven in the 8 MHz band and ten in 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 proliferation of passive and active distribution network components in the US operating in the band up to 1000 MHz, although the operating band of the majority of existing networks is still limited to 862 MHz. The standard does not impose other restrictions on the frequency distribution of channels, although they may be dictated by the state of the spectrum or the characteristics of the modulators.

The maximum bandwidth of one reverse link is still limited to 6.4 MHz, which allows transmission up to 30 Mbps. But the cable modem must be able to transmit at least 4 channels simultaneously. When it is necessary to go on line with a certain application, the cable modem sends a request to the CMTS, which allocates slots for this purpose within one or more channels. The maximum number of channels that the modem can operate on 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 be useful for administration purposes, and in the future for assignment to subscribers.

The third innovation multicast support. 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 a modem, but to a CPE(Customer Premises Equipment) connected to the modem's local network. For them, mechanisms for delivering multicast traffic can be supported and a certain QoS can be assigned. The latter feature obviously requires QoS to be maintained on 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 the service class (Service Class Name) within which a given set of QoS mechanisms is implemented.

Introduced in CMTS proxy support for the TFTP (Trivial File Transfer Protocol) server, which allows you to speed up the download of configuration files while connecting a large number of modems.

An important point is to improve the security of transmission. DOCSIS 3.0 introduced the 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, it has become possible to download software securely and a number of other improvements.

It should also be said that the expansion of functions, and, most importantly, the emergence of the modular CMTS concept, which is discussed in the next paragraph, is essential. complicate the OSS operational support system(Operations Support System). The number of MIBs used by this SNMP-based system has increased from 1385 (DOCSIS 2.0) to 2130. Moreover, there is no backward compatibility of systems in terms of network monitoring.

Modular CMTS

Simultaneously with DOCSIS 3.0, the concept of a modular CMTS was introduced. Its main idea is that the formation of RF signals is taken out of the CMTS into 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. The M-CMTS Core in this scheme retains the functions of DOCSIS packet distribution and synchronization, packet classification, quality of service management and security.

This separation is primarily due to the fact that the access segment in modern networks is increasingly approaching the subscriber. In the case of an integrated CMTS architecture, they must be installed in 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 using one CMTS located at the central office, and installing Edge-QAM devices at the edge of the transport network. These devices can be simultaneously used for converting TV streams. The idea of ​​separating the RF interfaces has been implemented only for the forward channel so far, the receivers of the reverse channel streams continue to be integrated with the CMTS, which reduces the value of this modular solution. The price for the flexibility of the architecture was the appearance of additional servers that coordinate the work of spaced components.

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

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

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 requirements of DVB / MPEG to the value of the relative packet delay. The DTI interface was developed for M-CMTS interaction with the DOCSIS Timing Server, and the ERMI interface for interaction with the Edge Resource Manager.

DOCSIS 3.0 can also be implemented in integrated CMTS (I-CMTS) that have a traditional architecture. Moreover, the first implementations of Pre-DOCSIS 3.0 equipment are based on the traditional architecture.

Specifications.

The characteristics of DOCSIS 3.0 are summarized in four white papers and one white paper, available from the Cable Labs website.

• The Media Access Control and Upper Layer Protocols Interface (MULPI) specification defines forward and reverse channel binding, compatibility with IPv6 addressing and its coexistence with IPv4, transfer of information about the use of multicast from cable modems to CMTS, and a standardized QoS mechanism for multicast sessions.
• The PHY specification (Physical Layer Specification) provides a typical system architecture, as well as the principles of generating and processing DOCSIS signals.
• The SEC specification (Security Specification) defines the principles of encryption and key administration when closing transmitted data with the AES algorithm.
• The OSSI (Operations Support System Interface Specification) specification, in addition to channel bonding, IPv6, multicast, and enhanced security, details the principles of receiving multiple reverse channels on a single port, ways to upgrade the network topology to implement DOCSIS 3.0, as well as advanced methods for diagnosing and monitoring signal quality , collecting network performance parameters and applying 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.

Market condition.

Thus, the standard offers many new features, varying in complexity and urgency of implementation. So, for example, a bunch of direct channels is implemented easier than a bunch of reverse ones. At the same time, due to the asymmetry of most "heavy" applications, a bunch of direct channels is more relevant today. Therefore, it is no coincidence that the bundle of direct channels in CMTS was implemented two years earlier than the bundle of reverse ones.

In order to facilitate and accelerate the introduction of certified devices to the market, Cable Labs has established three stages of CMTS qualification with DOCSIS 3.0 support. Depending on the degree of completeness, they were called gold, silver and bronze. Gold, meaning full certification, is awarded to a CMTS that meets all requirements of the specification. A complete list of the requirements of the two lower levels is provided only to manufacturers of certified equipment, but judging by press releases from Cable Labs, a bronze qualification is assigned to equipment if it provides a bundle of 4 channels in forward direction, and silver, 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. Bronze qualification was given to CMTS Arris C4 and Cisco uBR10012, and silver was awarded to CMTS Casa Systems C 2200. In the coming days, the results of the next, 57th wave of certification should become known.

As far as modems are concerned, only full certification is provided for them, which requires their verification 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 2.0V modems that support a bunch of direct channels.

Implementation.

In the US, home of the standard, operators have been slow to commercialize 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 a bundle of channels. For example, the Singaporean Starhub network implemented a pre-DOCSIS 3.0 system with a bundle of three channels, allowing the transmission of streams up to 100 Mbps, using CMTS and Motorola subscriber modems. And in the Canadian Videotron network, a system was also launched with a bundle of three channels.

So! The subtleties of buying a router:

If you are 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 that end, I've compiled five of the most popular questions from readers that I usually receive on the subject. cable internet. I've included both short and long answer options for each question, including suggestions on how to save on your monthly bill (spoiler alert: buy, don't rent your cable modem).

What cable modem do you really need?

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

Note: Your actual Internet connection speed depends on the speed of the modem, router, Wi-Fi connection, switches, and the user device itself, and by the way, on which 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:
cable modem A device that receives an Internet signal from a cable provider and converts it into a data signal that computing devices such as personal computers, tablets or smartphones can understand. The modem comes with a coaxial female 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 your hands on 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 the two is the standard they support, which defines the internet speeds it's capable of supporting, both for downloading and uploading. This standard is called d ata over cable service interface specification, or DOCSIS.

There are currently DOCSIS 1.x, DOCSIS 2.0, and DOCSIS 3.0 modems on the market. Both DOCSIS 1.x (mostly a now obsolete standard) and DOCSIS 2.0 support only one channel, which supports 43Mbps download and 10Mbps and 31Mbps uploads, respectively.

In DOCSIS 3.0 (which is backwards compatible with older standards), the single link rate remains 43 Mbps download and 31 Mbps upload, but modems are now capable of handling multiple channels (link 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 uploads, they usually support four channels, offering speeds up to 124 Mbps. Relatively soon, DOCSIS 3.0 modems will appear that 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're paying for an internet plan with download speeds of 30 Mbps or less, chances are you'll be fine with a DOCSIS 2.0 modem, which costs almost half the price of DOCSIS 3.0. Moreover, if your tariff is called: Lite, 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 offer upload speeds of only 10 Mbps. In addition, you need to check if 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 one ISP comes across that does not allow the use of consumer modems in its network.

In a typical home network, it is necessary to connect the modem to the WAN port of the Wi-Fi router using a (preferably) short network cable.

Rent or buy?

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

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

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

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

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

New, used, or returned?

Short answer:
It never hurts to get a brand new modem, but you can save just as much and lose nothing if you buy used or return it.

Long answer:
Cable modems are simple devices and after the initial installation they are usually not touched, they just remain in the same place. You will never change settings or tweak anything again. There are also no moving parts in the modems (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 do you any more good than getting a returned modem of the same type.

In truth, the most common reasons for returning modems are either no further need for them, or a mismatch. appearance interior design devices. And from the inside, they are practically no different from new devices. In many cases, the modem that the ISP offers you may be just after the return, and this device was used by previous customers. On the market, modems after return cost up to two-thirds of the price of a new one.

Purchasing used modems comes with 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 used, make sure you can return it after a few days, because if it can work for a few days without a problem, then there is a chance 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 modem failure is the power adapter, which is fairly easy to replace.

Buy a modem with a built-in router or two separate devices?

Short answer:
Unless your ISP provides you with a modem with a built-in router for free (which is unlikely), always just ask for a modem and purchase a router separately. After receiving the modem, simply take one of the routers, not the most expensive one, according to your need. If you really want a combo device for practical reasons like reducing the amount of wires, the Motorola SBG6782-AC Surfboard eXtreme is your the best choice at the moment. Make sure you read its full review first.

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

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

If you're in business, try to avoid purchasing a combo device because the router part of it probably won't have all the configuration options your business needs. Capable System Administrator can still get things working by adding another router to the network, but it's a lot more work than just getting a modem and the right router at the same time.

Do I need to purchase an extended warranty?

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

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

Should I try to bring down the price?

Definitely!!

It's true that most of us live in an area served by just one cable company, but there are other alternatives such as FDDI, satellite, or DSL (which is almost everywhere and usually cheaper). You should use them as your leverage in negotiating with the cable company for a better deal. You can also get better deals by subscribing to multi-service packages such as TV, Internet and phone, although don't subscribe to anything you don't plan on using.

Some cable companies may give you good terms for a period of time, say six months, and then start charging you the full rate, which is up to 50 percent higher. You can always dial an operator or look on the site for 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 for new promotions or discounts, or just give them a call 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 have any other questions, feel free to write to me at

The scalable 5354 is cable certified and also certified by Comcast, Time Warner Cable and other leading cable providers. It uses the Broadcom BCM3383G chipset and is equipped with Broadcom Full Band Capture (FBC). FBS Allows the modem to use any downstream frequency without adjacent channel restrictions or specific capture bandwidth windows.

The 5354 scalable model integrates the N300 Wireless-n Router, which has two internal antennas, 4 GigE LAN camera ports, and 2 USB ports for network cable name storage. User setup is simple and includes a quick and secure wireless setup using the unique security settings shown on the bottom label.Wireless WiFi is compatible with high bandwidth and wide range.Four GigE LAN ports provide wired connection to computers, TVs, HomePlug adapters, MoCA adapters and other devices. Two USB ports allow users to connect a USB flash drive or hard drive for Network Addressed Storage (NAS) and/or DLNA-enabled streaming media.

The router is also equipped with a powerful security firewall, parental controls and support for up to 253 client devices. Wireless features include advanced wireless security, WDS for extending wireless range using repeaters, and WPS for easy wireless setup.

Model 5354 Support for remote connection to IPv4 and IPv6.

Integrating a cable modem with a router saves workspace, simplifies setup, reduces cable clutter, and eliminates points of failure created by wired connections between individual devices. This product is designed and built for high performance today and for years to come. He has One year warranty and quality technical support fromUSAZoom Telephonics, a leader in communications products for over 37 years.

Please note that the sale of this product is limited to use by cable service providers on their own cable networks. Packed in a plain brown box labeled "not for resale".

Model 5354 features include:

• DOCSIS 3.0/2.0/1.1 performance with CableLabs, Comcast and Time Warner Cable Certification

• Up to 8 downlinks and 4 uplinks, with wideband capture

• Provides shared high-speed internet via cable:

Wi-Fi Compatible 802.11n, g, and b wireless devices

Devices with an Ethernet port, including computers and gaming stations

• Easy setup and management with unique on-label security settings, universal plug and play (UPnP), WPS wireless security setup, and browser-based control

• Four 10/100/1000 (Gigabit) Ethernet ports

• Two USB NAS ports with DLNA support for media servers

• Includes Advanced Firewall and Wireless Security

• One year warranty and support from Zoom, the U.S. communications leader since 1977

Specifications

Working parameters:

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Transfer rate:Up to 343 Mbps (8 channels)Up to 123 Mbps (4 channels)

Frequency:

Modulations: 64 or 256 QAM

Working level range:-15 to +15 dBmV

8 to +58dBmV (QPSK)

Status indicators:

Ethernet LAN interface:

USB interface:

Wireless connection:

Network Solutions:

IPv4 and IPv6

Router mode:

Dynamic DNS

DHCP server and client

Mosta

RIP V1 and V2

Control:

SNMP v1, v2, v3

Safety:

Parental control

Attack protection

IP/MAC/Port Filtering

Denial of Service

WiFi wireless network:

2 transmit/receive, MIMO

802.1x authentication

8 SSIDs

Transmission power: 20 dBm

The size:

Weight of packing:

1.25 lb (57 kg)

Power adapter:

110V/220V alternating current

12 volt 2 amp output

Working temperature:

0 °C to 50 °C

System requirements:

Must have an Ethernet port.

Any bike trip.

Guarantee:

One year

Package included:

Power cube

Stand

Ethernet cable

Quick start flyer

Specifications

Cable modem service interface:

F-type female 75 Ω (standard coaxial connector)

Working parameters:

descendingascending

Transfer rate:Up to 343 Mbps (8 channels)Up to 123 Mbps (4 channels)

Frequency: 88 to 1002 MHz (edge ​​to edge)5 to 42 MHz (edge ​​to edge)

Modulations: 64 or 256 QAM QPSK and 8, 16, 32, 64, 128, 256 QAM

Communication channels: Up to 8 channels Up to 4 channels

Working level range:-15 to +15 dBmV A-TDMA: +8 to +54 dBmV (32QAM, 64QAM)

8 to +58dBmV (QPSK)

S-CDMA: +8 to +53 dBmV (all modulations)

Status indicators:

Power, downlink, uplink, online status, wireless link, WPS, 4 Ethernet LAN, 2 USB ports

Ethernet LAN interface:

4 X RJ-45 10/100/1000 Mbps Ethernet, with auto-MDI/MDX

USB interface:

2 X USB 2.0 with UPnP and support for DNLA media servers and network storage

Wireless connection:

802.11n/g/b, 2X2 MIMO (multiple input multiple output)

Network Solutions:

IPv4 and IPv6

Router mode:

Dynamic DNS

DHCP server and client

NAT (network address translation)

Mosta

Fragmentation and IP Reassembly

NTP (Network Time Protocol)

Support port forwarding/DMZ

RIP V1 and V2

Support for up to 253 client devices

Quality of Service (QoS) support

Control:

SNMP v1, v2, v3

Support remote firmware update

Versatile plug and play

Safety:

Unique factory label security settings for each device

Packet Status Inspection (SPI)

VPN end-to-end: PPTP, IPsec tunnel

Parental control

Attack protection

Password protected system management

IP/MAC/Port Filtering

Denial of Service

Wireless mac address filtering

Supports time display under reference conditions Encryption (BPI) Management

Universal Plug and Play (UPnP)

Cable Management Diagnostic Log

WiFi wireless network:

Complies with IEEE 802.11n, g and b standards

Wireless data rate up to 300 Mbps*

2 transmit/receive, MIMO

Frequency band 2.4GHz-2.484GHz ISM band

Wireless Distribution System (WDS)

Wireless Multimedia (WMM/WME)

64/128 bit wired privacy equivalence (WEP) with passphrase

Wi-Fi Protected Access (WPA2, WPA) with pre-shared key

Wi-Fi Protected Security (WPS)

802.1x authentication

8 SSIDs

Wireless QoS

Transmission power: 20 dBm

Two external antennas adjustable position (2 dBi)

The size:

9.5" wide x 6.5" x 1.25" (24.1x16.5x3.2cm)

Weight of packing:

1.25 lb (57 kg)

Power adapter:

110V/220V AC 50/60Hz input to power adapter

12 volt 2 amp output

Working temperature:

0 °C to 50 °C

System requirements:

The cable modem must be connected to a cable modem service that uses any of the

DOCSIS-3.0, 2.0, or 1.1 standards.

Directly connected devices such as computers, switches and home connection adapters,

Must have an Ethernet port.

. Devices connected wirelessly must have Wireless-N, Wireless-G, or Wireless-B (Wi-Fi)

Any bike trip.

Guarantee:

One year

Certifications: Toy Safety Certifications

UL 60950-1 BV Safety Certification, FCC Parts 15B and 15C, Cables, Comcast, Time Warner Cable

Package included:

DOCSIS 3.0/2.0/1.1 cable modem

Power cube

Stand

Ethernet cable

Quick start flyer

Manufactured in mainland China with additional quality control tests in North America.