Recommendations from ITU-T’s Study Group 9
provide the first steps towards the next generation of cable modems. According
to SG insiders new cable modems will boost bandwidth, increase security and
provide greater flexibility overall for network operators to deploy data
J.210-J.212 provide a basis for modularizing cable modem termination systems
(CMTS) and were designed as an extension to the DOCSIS Recommendations to allow
for flexibility and independent scaling of certain CMTS functions.
(data over cable service interface specifications) – defined in Recommendations
J.112 and J.122 - specifies transmission systems for interactive cable television
services - IP cable modems. It defines the requirements for the two fundamental
components that comprise a high-speed data-over-cable system: the cable modem
(CM) and the CMTS.
modular-CMTS (M-CMTS) architecture splits the CMTS function into three
fundamental components: the M-CMTS Core, the EQAM (downstream modulator), and
the Timing Server. Inasmuch as the modular components may be located on
different chassis, and potentially at different physical locations, the new
Recommendation J.211 (Timing Interface for CMTS) provides the robust and highly
accurate transport of timing signals from the Timing Server to the other
components of the M-CMTS network in order to ensure that the system components
work in lock-step.
J.212 defines the protocol used to tunnel downstream user data across an
Ethernet network between the M-CMTS Core and EQAM. Finally, the new
Recommendation J.210 defines the downstream physical layer modulator
requirements for the EQAM.
new Recommendation in the DOCSIS series, J.213, describes requirements on both
CMTSs and CMs in order to implement a Layer-2 Virtual Private Network feature
which allows operators to offer a Transparent LAN Service along the lines of