Com21

Com21 Inc.

Former type	Public (NASDAQ: CMTO)
Industry	Computer networking
Fate	Bankruptcy
Founded	1992
Defunct	2003 (2003)
Headquarters	Milpitas, California
Number of employees	260 (2000)

Com21 was an early pioneer in developing cable modem networks in the era before the standard DOCSIS was introduced for Internet access via cable television networks. The company filed for bankruptcy in 2003.

Com21 Inc. was an American public company. Com21 shares traded on Nasdaq using CMTO as symbol. The headquarters of the company was located in Milpitas, California. Com21 had offices in 13 countries. The European head office was located in Delft and had a development centre in Cork, Ireland. In 2000 the company had over 260 employees.

Com21 was quite successful with their cable modem line of products in the years before the new standard DOCSIS was available. The Com21 portfolio can be divided into three segments: the central or head end equipment, cable modems or CPE, and the management platform.

The central system, typically installed in the head end or CATV hub locations were called ComControllers. A ComController provided the same function as a CMTS in modern Docsis networks. A ComcCntroller was a 19" rack module that was built around an integrated ATM switch and needed several modules to become a functional cable modem head end system. The main components or modules in a ComController were:

The management module provided the interface between each ComController system and the Com21 network management platform NMAPS. The management module offered a single Ethernet interface to an out of band management network.

Each ComController had one HF Downstream module. The downstream controller had two F-connector interfaces to connect a coax cable towards the distribution section of a hybrid fibre coax cable TV network. Below the primary interface a test interface connector was available, making it possible to connect test equipment without having to disconnect the main downstream signal from the network. The frequency of the downstream signal was configurable via the management interface.