by March 1, 2001 0 comments

DOCSIS, or Data Over Cable Systems Interface Specification, is a set of
documents that defines interface requirements or specifications for developing
standard, interoperable cable modems. A cable modem is a device that allows
high-speed data access via the cable TV network.

Before DOCSIS, different vendors were making their own proprietary cable
modems and other interface equipment. Due to this, interoperability amongst the
equipment was a major issue. If a cable company was using network equipment from
one vendor, it couldn’t use another vendor’s equipment.

DOCSIS takes care of this problem by introducing a set of 12 cable modem
specifications (covering various equipment) that would make them interoperable.
These include the Cable Modem to Customer Premise Equipment Interface (CMCI),
which is the interface standard between a customer’s computer and the cable
modem; Cable Modem Termination System-Network Side Interface, which is the
interface standard between the cable modem termination system (CMTS) and the
data network; Operations Support System Interface (OSSI), which is the network
management layer interface standards between the network elements and the
operating system; Telephony Return Interface, which is the interface between the
cable modem and a telephone return path; Radio Frequency (RF) Interface
specification that defines the RF interfaces between the cable modem and the
cable network; and the Security (Baseline Privacy) specifications, which covers
the data over cable security specifications.

These specifications contain detailed information about how each of these
equipment should be made. Covering them, therefore, is not possible in this
little space. You can check out www. for details.

CableLabs is the certifying authority for DOCSIS compliance. It’s a
research and development consortium of cable TV system operators. Cable modem
vendors have to submit their products to this lab. If their equipment conforms
to the DOCSIS specifications, they get an interoperability seal from CableLabs.
Before receiving the seal of interoperability, a cable modem supplier will have
to complete the CableLabs conformance checklist, submit an affidavit of DOCSIS
conformance, and successfully complete CableLabs’ test suite for DOCSIS
compliance. A list of CableLabs certified products is available at

Neelima Vaid

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