Who Makes What: Docsis 3.0 Equipment

Who Makes What: Docsis 3.0 Equipment

March 26, 2009

22 Min Read
Who Makes What: Docsis 3.0 Equipment

Cable operators worldwide – from Brazil, to Japan, to Korea, to Singapore, to North America – are now moving to Docsis 3.0, the latest evolution of the CableLabs Docsis specifications and the cable operators’ big hope to countering the speed advantages that telcos are beginning to see from their fiber deployments. See, for examples:

  • Cablevision Says to Watch for Wideband

  • RCN Claims to Chase Competitors in Wideband

  • TWC in '09: Job Cuts, WiMax & Wideband

  • ONO! Another Docsis 3.0 Story!

  • J:COM Does Docsis 3.0 All Over

  • Comcast Widens Wideband Footprint

  • A Decade of Docsis

Docsis 3.0 (sometimes branded as "wideband") seems set to spark a new round of competition as operators scramble to prove that "ours is faster than theirs." (See Shaw Breaks 100-Meg Barrier).

And it’s not just a pure bandwidth play for the cable operators. Docsis 3.0 capabilities, when combined with PacketCable 1.5 VoIP applications and so on, make it possible to produce very functional customer premises equipment (CPE), thereby helping cable operators to deliver converged services.

Given that market analysis firm Infonetics Research Inc. estimates that the number of worldwide standard and wideband cable broadband subscribers exceeded 66 million in 2008 (and could top 97 million in 2011), the market opportunities for ultrafast cable broadband look to be considerable.

For all this to happen, of course, the first CableLabs-certified or fully qualified Docsis 3.0 products have recently appeared. Ubee Interactive (formerly Ambit Broadband), Arris Group Inc. (Nasdaq: ARRS), Cisco Systems Inc. (Nasdaq: CSCO), Motorola Inc. (NYSE: MOT), and SMC Networks Inc. received the first certifications for Docsis 3.0 cable modems; and Casa Systems Inc. scored the first "Full" qualification for a Docsis 3.0 cable modem termination system (CMTS), in May 2008. A month later, Arris and Motorola received the first certifications for Docsis 3.0 embedded multimedia terminal adaptors (EMTAs), thereby combining VoIP services with the high speeds offered by wideband.

Since then, more products have been certified, and more will be, as the move to Docsis 3.0 gains momentum. However, as this report shows, the number of certified or declared Docsis 3.0 products is still fairly small: Docsis 2.0 still rules the roost in many vendors’ product catalogues.

This report provides a short roundup of who's currently who in the Docsis 3.0 business and an overview of some recent drivers and product/technology developments. It uses a very simple breakdown into vendors of CPE (cable modems and EMTAs), network gear (cable modem termination systems and edge quadrature amplitude modulators) and specialized silicon. We have tried to make the listing as complete as possible, but this is where you, Dear Reader, can help with any companies that have been missed.

If any companies need to be added, or any information corrected, please bring it to our attention either on the message board below or by sending an email to [email protected] or to [email protected], placing "Who Makes What: Docsis 3.0" in the subject line.

To try to forestall some of the inevitable howls of protest from some quarters of the industry, we are well aware that there are many, many vendors of cable products that are Docsis x capable, where x = 1, 1.1, 2.0, or even, perhaps, 2+ – as some proprietary approaches have anticipated aspects of Docsis 3.0. But the number of declared Docsis 3.0 products that we have found is still very small, although this will doubtlessly increase.

Here’s a hyperlinked contents list:

— Tim Hills is a freelance telecommunications writer and journalist. He's a regular author of Light Reading reports.

Next Page: Docsis Dossier

Docsis – Data Over Cable Service Interface Specification – is a long-established and evolving family of technology specifications developed by CableLabs for enabling two-way high-speed data transmission over hybrid fiber/coax (HFC) networks.

Docsis 1.0 appeared in 1997, followed two years later by the Docsis 1.1 revision, which added QoS capabilities. Further enhancements (such as increased maximum upstream bandwidth to around 30 Mbit/s compared to the original 10 Mbit/s) emerged in 2001 in the Docsis 2.0 specification. The most recent version is Docsis 3.0, which was released in mid-2006. The specification continues to evolve slightly through change requests from interested parties, but a CableLabs spokesman describes it as “98.6% closed out." (See Docsis 3.0 Specs Head to the Freezer .)

Figure 1 shows the baseline Docsis architecture in very simplified form. The cable modem termination system (CMTS) is located typically at the cable headend or hub, and plays a role similar to the DSLAM in DSL networks, terminating both the upstream and downstream data from and to the customer, and linking onwards to the Internet or the operator’s IP network. The edge quadrature amplitude modulator (eQAM) modulates the data onto the RF signal(s) transmitted over the (bonded) channel(s) to the customer’s cable modem (CM), which has a role analogous to that of the DSL modem. Finally, by using the PacketCable specifications, CMs can be integrated into other devices known as embedded multimedia terminal adapters (EMTAs) to support VoIP applications.

5128.jpgAll versions from 1.1 upwards assume an industry-standard HFC cable architecture, and there are corresponding EuroDocsis versions for cable networks using the European 8 MHz TV channel spacing instead of the North American 6 MHz.

Docis is also an International Telecommunication Union, Standardization Sector (ITU-T) Recommendation: J.122 (Docsis 1.0/2.0) and J.222 (Docsis 3.0). An important point is that all the Docsis versions are cross-compatible, so that the two end devices of the architecture – the home cable modem and the CMTS – will automatically use the lower version supported between them.

New! Improved!
Docsis 3.0 is important to cable operators because it supports much higher upstream and downstream bandwidths than Docsis 2.0, and also supports IPv6. With the increasing availability of telco fiber access, whether to the home, building, or curb, cable operators need an upgrade path to meet this competition. And IPv6 will offer them much more potential to manage the large numbers of consumer CPE that the future digital home could connect to the cable network.

There are also other enhancements over earlier versions, especially in terms of security, where the use of Data Encryption Standard (DES) to protect the link to the CPE has been abandoned in favor of the much more secure Advanced Encryption System (AES). The provisioning process has also been strengthened against certain hacks against the cable modem.

Docsis 3.0 obtains its higher speeds by the technique of channel bonding (or inverse multiplexing, as it is sometimes called) in which multiple 6 MHz or 8 MHz channels are logically combined, thereby greatly increasing the throughput compared to just the single channel used previously. The basic Docsis 3.0 specification cites a minimum of four bonded channels (for both upstream and downstream), but vendors are free to increase this if they wish, and currently much of the industry seems to be aiming for eight – Docsis, after all, is an interface specification, and doesn’t seek to limit the upside on what can be achieved by bonding multiple channels. So the label “Docsis 3.0” on a product or service doesn’t of itself say much about the maximum bit rates obtainable. It’s necessary to read the small print.

How this translates into a usable bit rate for the customer is complicated further by the fact that different vendors and operators obtain different per-single-channel rates – typically from about 38 Mbit/s to 40 Mbit/s. So Table 1, which compares the various versions of Docsis, is only an approximation.

Table 1: Docsis Approximate Maximum Usable Bit Rates


Upstream, Mbit/s

Downstream, Mbit/s












152 (4 channels), 304 (8 channels)

Channel bonding has also the desirable result of helping to reduce latency and jitter introduced at the PHY layer, since the physical transmission path is paralleled by the channels that have been bonded. This is nice for voice and video services, which is very much what cable operators are interested in, but, of course, it does nothing to improve things at the MAC and higher layers.

Note that some vendors’ pre-Docsis 3.0 systems already support some Docsis 3.0-type capabilities – for example, the Docsis 2.0 cards on BigBand Networks Inc. (Nasdaq: BBND)'s M-CMTS support downstream channel bonding. [Ed. note: BigBand has since gotten out of the "core" CMTS business but still makes eQAM gear; please see BigBand Terminates CMTS.] As there have been various proprietary approaches to channel bonding, Docsis 3.0 creates a standard, interoperable way of doing this and, in principle, removes the need for specific CMTS/CM combinations.

Also, higher downstream speeds have been implemented without channel bonding. This is the approach taken by C9 Networks , for example, in its C4400 CMTS, which has a capacity of four DS or 160 Mbit/s downstream, but without bonding. Customers can use existing 1.0/1.1/2.0 cable modems with a maximum of 40 Mbit/s to a single customer, but, once bonding is implemented, the capacity increases to a 160 Mbit/s bonded channel.

Docsis 3.0 also improves the multicasting capabilities of the cable network by supporting RFC3376 IGMPv3 (as opposed to Docsis 2.0’s IGMP) and RFC3810 MLDv2, which together mean that source-specific multicasting (SSM) is possible. SSM adds an extra layer of security to multicasting by making the stream’s source address one of the criteria for membership. The improved multicasting offers QoS, too, so that the CMTS can define and manage the appropriate level of QoS for a specific multicast session to the joined devices. Again, this is very nice for video services and video-on-demand (VoD) – key drivers for additional bandwidth in the first place.

And, to be really nerdy, there’s a new protocol for managing devices: IP Data Record/Streaming Protocol (IPDR/SP). This is an XML-type protocol and will give cable operators access to more information, more efficiently than SNMP (but which continues to be supported).

Next Page: Cable Modems & EMTAs

For the customer, the cable modem (CM) and embedded multimedia terminal adapter (EMTA) are the most visible parts of Docsis 3.0. And, since the customer is paying for them, their cost is critical to how quickly ultrafast cable broadband can become a mass-market phenomenon.

Greatly increasing the throughput of the CM through channel bonding inevitably requires faster processing, more memory for buffering, and faster interfaces (Gigabit Ethernet and USB 2.0) for the home network side – all factors that increase costs and mean that Docsis 3.0 CMs will be at a price premium to Docsis 2.0 versions for some time. [Ed. note: At least one silicon vendor thinks a sub-$50 Docsis 3.0 modem will be achievable as more and more components are integrated; please see Broadcom: Sub-$50 Docsis 3.0 Modem in Sight .]

There is an incentive to start with the minimum of four bonded channels to keep prices to a minimum, and then work upwards. This so-called 4x4 configuration offers around 150 to 160 Mbit/s of downstream bandwidth and 110 to 120 Mbit/s of upstream bandwidth in 6 MHz-channel systems, which is much faster than the 50/20Mbit/s currently offered by Verizon Communications Inc. (NYSE: VZ) over fiber, for example.

How quickly vendors will move wholesale to higher configurations (such as 8x4, offering up to 320 Mbit/s downstream, which is generally seen as the next sensible increase) will presumably depend very much on how the competitive dynamics between the cable operators and the telcos plays out, and how seriously the cable operators target the business market for high-speed data. Some MSOs are also looking to deliver IPTV services via eight-channel downstream configurations. (See TI Flexes Docsis 3.0 Muscle .)

So a fairly typical early Docsis 3.0 CM is the BRG-35502 from Hitron Technologies Inc. This product, launched in March 2008, offers:

  • Docsis 3.0 / EuroDocsis compliance

  • RoHS compliance

  • 4x4 channel bonding with downstream data transmission speeds up to 160 Mbit/s and upstream up to 100 Mbit/s

  • RJ-45 10/100/1000BaseT Ethernet port; USB-A Host Interface for Web CAM, Wireless LAN or USB HD as NAS file server

  • SNMP management support – MIB-II, Ethernet-like MIB, Bridge MIB, Cable Device MIB, Baseline privacy Interface MIB, RF Interface MIB

  • IP address filtering and IPV6 support

Thomson S.A. (NYSE: TMS; Euronext Paris: 18453), however, launched in May 2008 its DCM475 Docsis 3.0 CM, which uses 8x4 channel bonding to support shared download speeds of up to 320 Mbit/s.

Docsis 3.0-certified CMs are also appearing specifically for business applications as the cable operators look for opportunities in the SME market. These devices essentially add extra features relevant to business networking to the basic consumer designs. For example, SMCD3BCM Business-Class Docsis 3.0 CM from SMC Networks Inc. includes capabilities for static IP, firewall, NAT, VPN termination, and highly featured CLI. (See New SMC Gear Is Docsis 3.0 Ready.)

The arrival of the first significant numbers of Docsis 3.0-certified CMs during 2008 was also accompanied by similarly certified EMTAs from vendors such as Arris, Thomson, and Netgear Inc. (Nasdaq: NTGR). Arris claimed in June 2008 that its Touchstone TM702G EMTA was the first in the industry to achieve both Docsis 3.0 and PacketCable 1.5 compliance, and trumpeted that this opened the way for cable operators “to deploy primary line telephony service in conjunction with channel bonded wideband data service, through the versatility and efficiency of one device in a customer's home.”

But industry firsts are not what they were, and within six months Netgear had launched a similarly endowed EMTA – the CVD31XT.Table 2 lists vendors of Docsis 3.0 cable modems and EMTAs.

Table 2: Vendors of Docsis 3.0 Cable Modems (and EMTAs)


CPE products include

Ambit/Ubee Interactive

U10C035 Docsis 3.0 Modem


Touchstone TM702G EMTA, Touchstone Wideband Modem WBM750


DPC3000 DOCSIS 3.0 Cable Modem, DPQ3202 EMTA

Hitron Technologies

BRG-35502 Docsis 3.0 Cable Modem


CM: SURFboard SB6120 Cable Modem. EMTA: SBV6120 SURFboard Digital Voice Modem


CMD31T Cable Modem, CGD34N Cable Modem, CVD31XT EMTA

SMC Networks

SMCD3CM Residential Cable Modem, SMCD3CM-DD (targeted to business services)


CM: DCM475. EMTA: DHG575

ZyXEL Communications

P2910 Cable EMTA

Next Page: Cable Modem Termination Systems

Rolling out a Docis 3.0 upgrade unfortunately involves a lot more than selling a lot of suitably priced CMs and EMTAs to willing consumers. Apart from related issues of upgrades to 1 GHz plant (Docsis 3.0 increases the upstream/downstream frequency bands from 5-42/88-860 MHz to 5-85/88-1008 MHz) and switched digital video (SDV) architectures, a major requirement is Docsis 3.0-enabled cable modem termination systems (CMTSs).

As Figure 1 shows, the CMTS can integrate the RF QAM (see next page), and this has been the traditional approach (the integrated CMTS or I-CMTS). However, there is a move toward separating out the edge QAM, thereby creating a modular CMTS (M-CMTS), which, it can be argued, adds more flexibility – in choice of vendors, upgrading and rollout, and upstream and downstream bandwidth allocations.

In the M-CMTS approach, the core CMTS and edge QAM are separate devices (but linked by open data interfaces such as Gigabit Ethernet), whereas in the I-CMTS approach they are combined into one device. Protagonists of M-CMTS, such as BigBand Networks, Cisco Systems Inc. (Nasdaq: CSCO), and Harmonic Inc. (Nasdaq: HLIT), argue that the separation of Docsis MAC processing from RF QAM signaling offers many advantages, including:

  • A best-of-breed approach, so, for example, less-expensive QAMs can be used as appropriate, thereby lowering capital expenditure.

  • Higher scalability for CMTS solutions because: (a) The larger investment is the core CMTS, so an M-CMTS approach allows the core CMTS to feed many edge QAMs (as opposed to the I-CMTS approach, where there is a limited number of RF ports) and fiber nodes. Thus the core CMTS is a shared resource that can serve a greater number of nodes (service groups), which is very beneficial for VOD. And (b) Video requires much bandwidth, which is a design strength of the edge QAM rather than the CMTS, which helps cable IPTV.

  • M-CMTS and Docsis 3.0 open up the architecture, thereby enabling innovation – for example, Harmonic's Direct-2-Edge (D2E) approach to cable IPTV, which bypasses the core CMTS and goes direct to the Docsis 3.0 cable modem through the downstream edge QAM.

However, it can be argued that migrating from a Docsis 2.0 to a Docsis 3.0 network is highly straightforward for the I-CMTS case, as it involves upgrading only a single device, whereas the M-CTMS case results in a more complex arrangement (see Figure 2).

5129.jpgFurther, some vendors are thinking in terms of a new generation of CMTSs that is necessary to handle other cable developments beyond the pure addition of Docsis 3.0 capability. For example, Casa Systems argues that its C3200 Docsis 3.0 CMTS goes further by:

  • Supporting the separation of downstream and upstream channel capacity in a single physical chassis, thereby providing flexible downstream/upstream channel ratios

  • Having higher channel density than a second-generation CMTS – up to 80 downstream QAM channels in 3 RU compared to the 12-14 RU that a second-generation CMTS needs to support even fewer

  • Supporting both Docsis and MPEG/DVB traffic in a single platform, thereby allowing cable operators to manage their HFC spectral resources in a single device

As an example of the flexibility of Docsis 3.0 channel bonding, the C3200 is capable of 16x16 operation – 16 downstream and 16 upstream channels.

Table 3 lists vendors of Docsis 3.0 CMTSs.

Table 3: Vendors of Docsis 3.0 Cable Modem Termination Systems


CMTS products include



Arris C4c CMTS

BigBand Networks

Cuda CMTS (product officially terminated in fall 2007)

C9 Networks

In development -- Pre-Docsis 3.0 capabilities in C4400

Casa Systems

C3200, C2200, and C10200


uBR10012 CMTS

Coaxial Networks

IRISNG Docsis 2.0/3.0 Cable Modem Termination System


Developing an outdoor DOCSIS 3.0 CMTS for small networks


BSR 64000 CMTS/Edge Router

Next Page: Edge Quadrature Amplitude Modulators

The RF Edge QAM perhaps has a somewhat lower profile than the CMTS, partly because, as already pointed out, there are two options on how this function can be implemented, and the I-CMTS approach somewhat hides it from view. Nevertheless, the edge QAM is a vital element as it provides the downstream PHY function, and its capabilities play a key role in supporting applications such as VoD, network DVR, switched digital video (SDV), and edge encryption.

Further, as Light Reading’s Cable Industry Insider report, "Docsis 3.0 Opportunities: IPTV & SMB Lead the Way," points out, the M-CMTS alternative creates the opportunity for the universal edge QAM, in which data and video services share QAM channels instead of using dedicated resources. As a result, cable operators using M-CMTSs can change a specific edge QAM's tasks based on the type of traffic it needs to handle at that time. So universal edge QAMs have begun to ship in increasing volumes, according to Infonetics Research, because of their suitability for both Docsis 3.0 and SDV.

Table 4 lists vendors that specifically offer separate Docis 3.0 edge QAMs. Key requirements include support for triple-play services, high port density, cost effectiveness, scalability, upgradability, and reliability. Further, the introduction of Docsis 3.0 does require the edge QAMs to support the following new interfaces in hardware and software (see Figure 2):

  • Docsis Timing Interface (DTI) Protocol, for synchronizing the M-CTMS components to a common timing reference

  • Downstream Radio Frequency Interface (DRFI), which allows multiple downstream channels on each RF connector

  • Downstream External PHY Interface (DEPI), which transports the control and data packets between the M-CMTS Core and the edge QAM

  • Edge Resource Manager Interface (ERMI), which is currently optional but helps managing the MAC domains

  • Operations Support System Interface (OSSI)

Table 4: Vendors of Docsis 3.0 Edge Quadrature Amplitude Modulators (EQAMs)


QAM products include


D5 Universal Edge QAM (UEQ)

BigBand Networks



xDQA-24 edge QAM


NSG 9000 universal edgeQAM

LiquidxStream Systems



APEX1000 Edge QAM

RGB Networks

Universal Scalable Modulator (USM)

Tandberg TV

EQ8096 Edge QAM


Virtuoso edge QAM

Vecima Networks

HyperQAM Universal Edge QAM

A typical example of a recent device is Harmonic's NSG 9000 universal edgeQAM, which was released in a higher-density form (with 144 QAM channels in 2 RU) in mid-2008. The NSG 9000 is described as a highly integrated digital video gateway, capable of performing multiplexing, scrambling, QAM modulation, encryption, and RF upconversion for on-demand content streamed over an IP network. The rack capacity has been doubled through a new 48 MHz (eight QAM field) upgradable module released in mid-2008, and the vendor says that the module’s technology maximizes bandwidth utilization by providing significant flexibility in allocating individual frequencies across the 48 MHz spectrum, rather than as adjacent or contiguous block of QAM channels.

To obtain high reliability, the HyperQAM from Vecima Networks Inc. (Toronto: VCM) combines automatic failover, redundancy, and hot-swap ability of the QAM modules, power supplies, and fans with granular redundancy on the Gigabit Ethernet input side of the platform from the CMTS. Vecima says that, with 10x1 GbE input ports, the 128 QAMs of HyperQAM can be sourced fully with five of the 1 Gigabit Ethernet inputs, while the remaining five are dedicated to redundant backup. The redundancy can be specified at resolutions ranging from the full Gigabit Ethernet, to the MPTS, SPTS, or program levels – so, if a single program fails on the live Gigabit Ethernet port, it will be sourced from the redundant port while other content continues to be pulled from the original port.

Next Page: Silicon

Docsis 3.0 devices inevitably use a range of silicon chipsets, but most do fairly standard things that are not specific to Docsis 3.0. Of those that are, the main development over the past year is chipset families and systems-on-a-chip (SOC) for CMs and CMTSs.Table 5 lists some vendors of silicon specifically for Docsis 3.0.

Table 5: Vendors of Docsis 3.0 Silicon Devices


Products include


BCM3380 CM chipset, Docsis 3.0 CMTS chipset


MT2170 Single-Chip Docsis 3.0 Wideband Tuner, MT1570 Wideband Upstream Amplifier

Texas Instruments

Puma 5 family of Docsis 3.0 chipsets

Typical of the chipset families is Texas Instruments Inc. (NYSE: TXN)'s Puma 5 cable modem, set-top-box (STB), and transport gateway platform, which received CableLabs Docsis 3.0 certification in May 2008. The family comprises the TNETC4800 for EMTA applications, TNETC4810 for cost-sensitive EMTA applications, TNETC4820 for advanced STB and multimedia applications, TNETC4830 for optimized data cable modem applications, and TNETC4840 for data and video applications. Of these, the 4820 is the most recent addition (May 2008) and reflects the growing industry interest in creating hybrid STBs as powerful in-home digital platforms.

So TI says that the TNETC4820 is compatible with both legacy QAM cable video and IP-based data streams, and can function as either a transport or video gateway into the home. It allows operators to deliver video over IP concurrently with an existing video over MPEG distribution system, and can translate any video signal into IP format for further delivery via the home network to other low-cost STBs. So the architecture includes high-speed interfaces like Gigabit Ethernet and USB 2.0 – and wireless networking, powerline technologies, and advanced coaxial networking solutions can also be integrated into the platform.

On the SOC side, Broadcom Corp. (Nasdaq: BRCM) laid claim to the industry’s first fully integrated CM SOC for Docsis 3.0 in January 2009 – its BCM3380 family, which offers bonding of eight downstream Docsis channels. The company says that only memory has to be added to provide complete Docsis functionality – an integrated multichannel upstream power amplifier and integrated Gigabit Ethernet and USB transceivers are included. It claims a technical first in integrating a flexible QAM receiver with split wideband tuners to avoid channel lineup limitations in single-frequency window approaches.

Working in conjunction with the BCM3380 family, and announced at the same time, is Broadcom’s CMTS chipset for Docsis 3.0. This includes the BCM3215 QAMLink octal downstream Docsis modular CMTS (M-CMTS) core media access controller (MAC); the BCM3216 QAMLink Docsis 3.0 upstream media access controller; and the BCM3142 QAMLink 12-channel universal advanced time-division multiple access (A-TDMA) and synchronous code division multiple access (S-CDMA) physical layer (PHY) receivers. As proof that specifications don’t thwart vendors’ claims for product differentiation, Broadcom says that, compared to other solutions, the QAM technology used “provides a 33% improvement over reverse path speeds and a 25% improvement over downstream speeds in support of the Docsis 3.0 specification.”

But Docsis 3.0 has led also to developments in the linear RF devices, such as wideband amplifiers and wideband and narrowband tuners, as the specification imposes, for example, strong transmit-noise and linearity requirements. For example, Microtune Inc. (Nasdaq: TUNE)’s new linear MT1570 wideband RF amplifier (announced in November 2008) amplifies four upstream data channels from the CM to the CMTS. It is integrated into a small 5mm x 5mm QFN 20-pin package, and Microtune emphasizes its backwards compatibility and coexistence with legacy Docis equipment, thereby eliminating the need for new cable infrastructure investment – something that many Docsis 3.0 vendors are keen to stress about their products.

— Tim Hills is a freelance telecommunications writer and journalist. He's a regular author of Light Reading reports.

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