VoIP Archives

19 03, 2014

The Future of Test Equipment

Mia Colabrese2014-03-19T11:54:39-04:00March 19th, 2014|

The Future of Test Equipment and the Role of Proactive Network Maintenance At a recent convention, I had the opportunity to listen to Daniel Howard, CTO of the SCTE, speak about how Comcast is using, Rohde & Schwarz in conjunction with their PNM (Proactive Network Maintenance) Scout Flux system. This highlights that although PNM is the future of troubleshooting cable plant problems proactively, high-end test equipment will still be needed. One common thread across the industry that I like to re-iterate is that the cable plant does not

14 11, 2011

Press Release

Mia Colabrese2011-11-14T07:00:04-05:00November 14th, 2011|

Press Release The Volpe Firm offering solutions, services and products for the broadband telecommunications industry The Volpe Firm gets Seal of Approval from Clients Alpharetta, GA November 14, 2011: The Volpe Firm offers solutions, services and products for the broadband communications industry with a focus in DOCSIS, data, video, and VoIP communications. We provide everything from specialized DOCSIS 3.0 seminars and or tailored DOCSIS training to high level hardware architecture engineering design and system troubleshooting. The Volpe Firm, with 30 years of combined telecommunications experience, specializes in DOCSIS,

5 09, 2010

DOCSIS 3.0 Tutorial – DOCSIS Does IPv6

Mia Colabrese2021-11-24T09:23:28-05:00September 5th, 2010|

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.

1 07, 2010

DOCSIS 3.0 Tutorial – The EQAM

Mia Colabrese2021-08-17T15:58:05-04:00July 1st, 2010|

In my article on DOCSIS 3.0 M-CMTS architecture, I talked about the distributed nature of the CMTS with an M-CMTS core (the CPU of the system), a DOCSIS Timing Server, and an edge Quadrature Amplitude Modulator (EQAM). I am going to cover the EQAM in detail in this article because in the past couple of years, EQAM (also spelled eQAM) has rapidly become part of our vocabulary but its operation and value often go unappreciated. Further, in order to fully understand DOCSIS 3.0 operation, downstream channel bonding, and possible issue which may arise, a thorough understanding of the eQAM is critical.

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.

16 02, 2009

Troubleshooting DOCSIS – VoIP Impairments > Delay & Jitter

Mia Colabrese2021-08-17T15:54:55-04:00February 16th, 2009|

In this blog I will address delay and jitter as they pertain to VoIP in a DOCSIS network. Delay, jitter and packet loss are the three primary impairment in a VoIP network, but packet loss was addressed in my Troubleshooting DOCSIS - VoIP Impairments > Packet Loss blog. After packet loss, delay is the second most disruptive impairment in VoIP networks. The effects of delay to the caller generally appear as echo and talker overlap. In PSTN communications, echo can arise as acoustic echo between the mouthpiece and

15 02, 2009

Troubleshooting DOCSIS – VoIP Impairments > Packet Loss

Mia Colabrese2021-08-17T15:45:30-04:00February 15th, 2009|

In this blog I am going to focus on VoIP packet loss, which is just one of the three (3) primary types of VoIP impairments that are present in a DOCSIS network. I will cover many RF and IP terms in this blog that I have not discussed in my previous tutorials, not to worry! This terminology is all fodder for future blogs. :-) To review, the three fundamental impairments which impact call quality of VoIP communications are as follows: * Packet Loss – The complete or partial loss of a packet containing actual voice payload. * Delay – The time a packet takes to traverse the space between the source and destination of a voice call. The space is comprised of both the physical distance the data must travel in addition to the active network routing and switching elements, which contribute additional delay. * Jitter – The variance of inter-packet arrival time from one transmitted packet to the next sequential packet.

13 02, 2009

Troubleshooting DOCSIS – VoIP Impairments

Mia Colabrese2023-02-18T10:49:47-05:00February 13th, 2009|

In this blog I am going to digress for a moment from my standard DOCSIS 101 tutorial and spend a little time on DOCSIS troubleshooting basics, especially with respect to Voice-over-Internet Protocol (VoIP). I am doing this as due to many offline questions specific to this topic. Don't worry, though I may start to inter-mix some troubleshooting blogs now and again, just check the DOCSIS 101 page to stay on top of the latest DOCSIS tutorial blogs.