Category Archives: DOCSIS 3.0

DOCSIS 3.0 | Impaired Service

December 21, 2011   Brady   2 Comments
DOCSIS 3.0 Impaired Service

“Impaired Service” in which case one or more bonded upstream channels are impacted by upstream RF impairments while other bonded channels are not. Since subscriber data is striped (that is broken into pieces and spread across each upstream channel and then re-assembled by the CMTS), some of the data will be lost or have errors while other data will not. Subscribers will most likely notice an impaired condition as upstream data rates slow down due to TCP/IP transmissions and/or VoIP, gaming, teleconferencing and other real-time applications will be noticeably impacted.

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DOCSIS 3.0 | Partial Service

December 07, 2011   Brady   1 Comment
DOCSIS 3.0 Partial Service

Partial Service is a new term encountered in the DOCSIS 3.0 MULPI specification and realized in field deployments of DOCSIS 3.0 cable modems using upstream bonding. This was a topic that I touched on in this years SCTE Cable-Tec Expo, but will explore in greater detail in this article. Partial service can be considered a feature because the cable modem will stay online even when one or more upstream transmit channels goes offline.

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BTR | Rollouts Continue as DOCSIS 3.0 Matures

September 28, 2011   Brady   No comments
DOCSIS 3.0 Matures

The following article just released by Broadband Technology Report was written by Carl Weinschenk.  A number of us from the industry contributed to Carl’s piece, but it is a nice high-level summary article on the status of DOCSIS 3.0.  Below you will find a snippet of the article with a link to the BTR website

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Why are my DOCSIS 3.0 cable modems transmitting at 52.2 dBmV?

September 09, 2011   Brady   3 Comments
DOCSIS 3.0 Cable Modem Maximum Transmit Power

A recent question from a reader provided an interesting response – the answer: maximum transmit power is 52.2 dBmV for DOCSIS 3.0 cable modems under certain conditions. The answer is very simple. They were transmitting at their maximum transmit level. That being in a 16-QAM modulation with four bonded upstream channels.

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Top 10 DOCSIS 3.0 Terms You Need to Know

September 05, 2011   Brady   No comments
Top 10 DOCSIS 3.0 Terms

This is the speak you need to know when talking DOCSIS 3.0 to any DOCSIS Engineer or specialist. It is important that you learn the full name, in many cases the acronym and also what value the particular terminology plays in a DOCSIS 3.0 network as it will likely be crucial in troubleshooting tough-to-diagnose DOCSIS impairments.

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DOCSIS 3.0 Modems Readily Available

June 25, 2011   Brady   1 Comment

If you have been upgraded to DOCSIS 3.0 and were issued a cable modem from your cable provider, you are probably paying a monthly fee for that device. I have always been a strong advocate of owning my own cable modems because it likely pay for itself over the two or three years you own it.

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DOCSIS 3.0 Tutorial – DOCSIS Does IPv6

September 05, 2010   Brady   7 Comments
DOCSIS 3.0 Cable Modems Support IPv6

Everyone is familiar with Internet Protocol version 4 (IPv4) addresses. You probably even set them up in your home network, such as 192.168.1.1 IPv4 is described in IETF publication RFC 791 (September 1981), which replaced the previous version RFC 760, dating back to January 1980. So its safe to say that IPv4 has been around for some time and serving us quite well. New in DOCSIS 3.0 has support for IPv6. Why do we need this new version? IPv6 has a vastly larger address space than IPv4. This results from the use of a 128-bit address, whereas IPv4 uses only 32 bits. Believe it or not, major cable operators are running out IP address. This is due to more customers, not just for cable modems, but also for set top boxes and VoIP eMTAs. Further, deployed in cable networks are IP devices such as power supplies with embedded cable modems for monitoring voltage, temperature, current and more. All networks are getting more IP devices requiring more and more IP addresses, so the 2128 addresses allocated in IPv4 are no longer sufficient and we turn to the 3.4×1038 addresses provided in IPv6.

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DOCSIS 3.0 Tutorial – Upstream Channel Bonding

August 22, 2010   Brady   5 Comments
DSAM DOCSIS 3.0 Throughput Test

The focus of this article will be on the mechanics of upstream channel bonding and how it works more from a DOCSIS protocol perspective. Much more detailed information can be found in the DOCSIS 3.0 MULPIv3.0 document located in the Library, but this will provide a high level overview for the layman who is curious about the basics. First lets understand that it is the cable modem that is doing the channel bonding, remember in the upstream the cable modem transmits data to the CMTS. Per DOCSIS 3.0, the CM can bond from one to four channels in the upstream as coordinated by the CMTS. The CM is always under control by the CMTS.

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DOCSIS 3.0 Tutorial – Downstream Channel Bonding

July 18, 2010   Brady   2 Comments

Downstream Channel Bonding is perhaps the ball bearings of DOCSIS 3.0, enabling subscriber data speeds in excess of 160 Mbps (4 times that of previous DOCSIS versions). While conceptually simple, the principle of combining multiple downstream DOCSIS channels together to carry the same user data must have tight constraints in order to preserve the integrity of the data and have the data arrive at the correct subscriber’s device and in sequence. This article will cover both the physical layer aspects and DOCSIS protocol aspects that enable channel bonding.

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DOCSIS 3.0 Tutorial – Basic Protocol 1

July 07, 2010   Brady   1 Comment

Now that we have established the two primary architectures available in DOCSIS 3.0, I-CMTS and M-CMTS (thought hybrids do exist), and the hardware components of these architectures, it is time to delve into the protocol of the DOCSIS specifications that make up DOCSIS 3.0. There are five primary specifications that I will be drawing upon from here on out listed below and located in my document library and also on the CableLabs website.

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