24 06, 2019
  • Low latency

Low Latency and Virtualization

2021-08-15T18:44:51-04:00June 24th, 2019|

Happy Friday Everyone.  Today is June 14th and this is episode 48 of Get Your Tech On, our show on All Things DOCSIS.  I'm Brady Volpe, Founder of The Volpe Firm and Nimble This.  With us is, John Downey. John is also CMTS Technical Leader at Cisco Systems, welcome John.    AQM (active que management) Mini slot proactive grant service OFDMA John thank you for your time today. This was a great episode. Our next Episode 49 is scheduled in July 12. We do our best to bring our

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2 10, 2009

Speeding Upstream – Part I

2021-08-18T10:19:55-04:00October 2nd, 2009|

The first part of this article (in CT's March 2009 issue) discussed downstream potential issues, while this one focuses on the potential issues associated with upstream deployments. In particular, this article covers the critical upstream areas that one should be aware of when getting ready to deploy or already deploying DOCSIS 3.0.

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9 03, 2009
  • docsis qos

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

2021-08-17T13:22:59-04:00March 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.

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28 02, 2009
  • DOCSIS Upstream Channel Descriptor - UCD

DOCSIS and Cable Modems – How it works :: UCD

2021-08-17T10:36:51-04:00February 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

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22 02, 2009
  • DOCSIS cable modem data burst defined

DOCSIS and Cable Modems – How it works :: Anatomy of a Burst

2021-08-17T22:35:57-04:00February 22nd, 2009|

DOCSIS Cable Modem Data Burst Defined Previously I have discussed that cable modems share the upstream channel by using Time Division Multiple Access (TDMA).  This means that when a cable modem is not transmitting data its RF transmitter is turned off.  In order to transmit data it must transmit a burst of data which contains a REQUEST to the CMTS.  The REQUEST relays the cable modem's Service IDentifier and the number of bytes of information the modem has to transmit in its buffer.  The CMTS prioritizes all incoming

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