MAC Archives

11 11, 2013

DOCSIS Burst Demod – SCTE EXPO 2013 – Fresh Tech

Mia Colabrese2013-11-11T09:00:21-05:00November 11th, 2013|

DOCSIS Burst Demod SCTE EXPO 2013 - Fresh Tech There were some new and exciting things at this years SCTE. There was a good drum line at the opening event but also there were new products and innovative ideas (Cisco and PNM). In test equipment this year at the SCTE EXPO Rohde and Schwarz, JDSU and VeEx all had some new things on display. None of the items are currently shipping (with the exception of R&S who used existing equipment) but it does show that test equipment vendors are

27 02, 2012

DOCSIS 3.0 Cable Modem Registration

Mia Colabrese2021-08-17T16:15:14-04:00February 27th, 2012|

This article will discuss the channel bonding process and ultimately the DOCSIS 3.0 cable modem registration process. In order to be able to understand this article, I will make many references to my prior article on Cable Modem Registration which focused on DOCSIS 1.x and 2.0 cable modems.

22 11, 2011

Fresh Tech | DOCSIS Protocol Analyzer – Can’t stop a good idea!

Mia Colabrese2021-08-18T10:13:29-04:00November 22nd, 2011|

When I first heard rumor that a knew company had a DOCSIS protocol analyzer floating around I had to see it! With full disclosure, many of you know that after 10 years in RF and fiber-optic transport equipment, I spent a few years designing, marketing and selling DOCSIS protocol analyzers. More specifically I focused on making them available to cable operators because I knew they could detect really difficult to isolate problems. Averna know owns the technology from my Sigtek days, so it is nice to see a new competitor in the space. What's more is that its nice to see this competitor at SCTE Cable-Tec Expo who is interested in cable operator's issues.

22 08, 2010

DOCSIS 3.0 Tutorial – Upstream Channel Bonding

Mia Colabrese2021-11-24T09:39:36-05:00August 22nd, 2010|

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.

18 07, 2010

DOCSIS 3.0 Tutorial – Downstream Channel Bonding

Mia Colabrese2021-08-17T16:09:16-04:00July 18th, 2010|

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.

7 10, 2009

DOCSIS Upstream – Part II

Mia Colabrese2021-08-17T13:40:53-04:00October 7th, 2009|

This article will focus more specifically on DOCSIS 3.0 issues that will occur as you are deploying DOCSIS 3.0 or post -deployment.

9 03, 2009

DOCSIS and Cable Modems – How it works :: Quality of Service

Mia Colabrese2021-08-17T13:22:59-04:00March 9th, 2009|

DOCSIS 1.0 enabled data over coax with a "best effort" service using a data request-grant methodology. DOCSIS 1.1 and subsequent specifications added guaranteed Quality of Service (QoS) by providing Unsolicited Grant Synchronization (UGS) which means that a cable modem does not have to send a data request in order to receive a bandwidth grant from the CMTS. The new UGS service is an enabling technology which has allowed cable operators to successfully deploy the highly revenue generating Voice-over-IP (VoIP) services. In the following sections I will illustrate the differences between best-effort (request-grant) and QoS (UGS) services.

3 03, 2009

DOCSIS and Cable Modems – How it works :: Station Maintenance

Mia Colabrese2021-08-17T15:43:18-04:00March 3rd, 2009|

While the UCD provides the language of the DOCSIS network, the Station Maintenance messaging is the proverbial "heartbeat" of the DOCSIS network. A station maintenance session consists of a Range Request sent from a cable and a Range Response sent by the CMTS. The CMTS analyzes the signal quality of the Range Request message and sends back any necessary RF adjustments in the Range Response message. This "handshake" between every cable modem and the CMTS must occur once every 30 seconds as dictated by the DOCSIS specification.

28 02, 2009

DOCSIS and Cable Modems – How it works :: UCD

Mia Colabrese2021-08-17T10:36:51-04:00February 28th, 2009|

Just as a picture is worth a thousand words, so is a complete Upstream Channel Descriptor (UCD) as seen by a cable modem. This message, sent every two seconds by the the CMTS, contains an enourmous amount of valuable information that every cable modem on a DOCSIS network needs to know in order to communicate. Often undervalued, the UCD is a virtual Hitchiker's Guide to the DOCSIS network! So without any further ado, let me show you an example of a full UCD message and then explain its contents further

9 02, 2009

DOCSIS and Cable Modems – How it works :: Cable Modem Registration

Mia Colabrese2021-08-17T09:54:53-04:00February 9th, 2009|

Through DOCSIS tutorial seminars, I have found the most effective way to bring someone up to speed on DOCSIS communications is by teaching the cable modem registration process. During the registration process, we will cover the RF physical layer, theDOCSIS Media Access Layer (MAC) and the Internet Protocol (IP) layer. Yes, the cable modem exercises the first three layers of the Open Systems Interconnection Reference Model (OSI Reference Model or OSI Model)...