Interactive video distribution systems – Video distribution system with upstream communication – Having link to external network
Reexamination Certificate
1999-09-29
2003-04-22
Lim, Krisna (Department: 2153)
Interactive video distribution systems
Video distribution system with upstream communication
Having link to external network
C725S100000, C725S086000, C709S218000
Reexamination Certificate
active
06553568
ABSTRACT:
FIELD OF INVENTION
The present invention relates to communications in computer networks. More specifically, it relates to data rate enforcement, such as class-of-service or quality-of-service service enforcement for service level agreements on a cable television network.
BACKGROUND OF THE INVENTION
Cable television networks such as those provided by Comcast Cable Communications, Inc., of Philadelphia, Pa., Cox Communications of Atlanta, Ga., Tele-Communications, Inc., of Englewood Colo., Time-Warner Cable, of Marietta Ga., Continental Cablevision, Inc., of Boston Mass., and others provide cable television services to a large number of subscribers over a large geographical area. The cable television networks typically are interconnected by cables such as coaxial cables or a Hybrid Fiber/Coaxial (“HFC”) cable system which have data rates of about 10 Mega-bits-per-second (“Mbps”) to about 30+ Mbps.
The Internet, a world-wide-network of interconnected computers, provides multi-media content including audio, video, graphics and text that typically requires a large bandwidth for downloading and viewing. Most Internet Service Providers (“ISPs”) allow customers to connect to the Internet via a serial telephone line from a Public Switched Telephone Network (“PSTN”) at data rates including 14,400 bps, 28,800 bps, 33,600 bps, 56,000 bps and others that are much slower than the about 10 Mbps to about 30+ Mbps available on a coaxial cable or HFC cable system on a cable television network.
With the explosive growth of the Internet, many customers have desired to use the larger bandwidth of a cable television network to connect to the Internet and other computer networks. Cable modems, such as those provided by 3Com Corporation, of Santa Clara, Calif., Motorola Corporation, of Arlington Heights, Ill., Hewlett-Packard Co., of Palo Alto, Calif., Bay Networks, of Santa Clara, Calif., Scientific-Atlanta, of Norcross, Ga., General Instruments, of Horsham, Pa., and others offer customers higher-speed connectivity to the Internet, an intranet, Local Area Networks (“LANs”) and other computer networks via cable television networks. These cable modems currently support a data connection to the Internet and other computer networks via a cable television network with a data rate of up to about 30+ Mbps, which is a much larger data rate than can be supported by a modem used over a serial telephone line.
However, many cable television networks provide only uni-directional cable systems, supporting only a “downstream” cable data path. A downstream data path is the flow of data from a cable system “headend” to a customer. A cable system headend is a central location in the cable television network that is responsible for sending cable signals in the downstream direction. A return data path via a telephone network (i.e., a “telephony return”), such as a public switched telephone network provided by AT&T, GTE, Sprint, MCI and others, is typically used for an “upstream” data path. An upstream data path is the flow of data from the customer back to the cable system headend. A cable television system with an upstream connection to a telephony network is called a “data-over-cable system with telephony return.”
An exemplary data-over-cable system with telephony return includes customer premise equipment (e.g., a customer computer), a cable modem, a cable modem termination system, a cable television network, a public switched telephone network, a telephony remote access concentrator and a data network (e.g., the Internet). The cable modem termination system and the telephony remote access concentrator together are called a “telephony return termination system.”
The cable modem termination system receives data packets from the data network and transmits them downstream via the cable television network to a cable modem attached to the customer premise equipment. The customer premise equipment sends response data packets to the cable modem, which sends response data packets upstream via public switched telephone network to the telephony remote access concentrator, which sends the response data packets back to the appropriate host on the data network.
In a two-way cable system without telephony return, the customer premise equipment sends response data packets to the cable modem, which sends the data packets upstream via the cable television network to the cable modem termination system. The cable modem termination system sends the data packets to appropriate hosts on the data network. The cable modem termination system sends the response data packets back to the appropriate cable modem.
As a cable modem is initialized in a data-over-cable system, it registers with a cable modem termination system to allow the cable modem to receive data over a cable television connection and from a data network (e.g., the Internet or an Intranet). The cable modem forwards configuration information it receives in a configuration file during initialization to the cable modem termination system as part of a registration request message. A cable modem also helps initialize and register any attached customer premise equipment with the cable modem termination system.
A cable modem termination system in a data-over-cable system typically manages connections to tens of thousands of cable modems. Most of the cable modems are attached to host customer premise equipment such as a customer computer. To send and receive data to and from a computer network like the Internet or an intranet, a cable modem and customer premise equipment and other network devices have a network address dynamically assigned on the data-over-cable system.
Many data-over-cable systems use a Dynamic Host Configuration Protocol (“DHCP”) as a standard messaging protocol to dynamically allocate network addresses such as Internet Protocol (“IP”) addresses. As is known in the art, the Dynamic Host Configuration Protocol is a protocol for passing configuration information to network devices on a network. The Internet Protocol is an addressing protocol designed to route traffic within a network or between networks.
Initialization information forwarded to a cable modem termination system from a cable modem may include Class-of-Service (“CoS”) or Quality-of-Service (“QoS”) requests. As is known in the art, class-of-service provides a reliable (i.e., error free, in sequence, with no loss of duplication) transport facility independent of the quality-of-service. Class-of-service parameters include maximum downstream data rates, maximum upstream data rates, upstream channel priority, guaranteed minimum data rates, guaranteed maximum data rate and other parameters. Quality-of-service collectively specifies the performance of a network service that a device expects on a network. Quality-of-service parameters include transit delay expected to deliver data to a specific destination, the level of protection from unauthorized monitoring or modification of data, cost for delivery of data, expected residual error probability, the relative priority associated with the data and other parameters.
A cable modem termination system is typically responsible for providing class-of-service and quality-of-service connections to a cable modem in a data-over-cable system. However, there are several problems associated with using a cable modem termination system to provide class-of-service and quality-of-service connections to a cable modem. One problem is that the cable modem termination system is responsible for handling and balancing class-of-service and quality-of-service requests for tens of thousands of cable modems. The handling and balancing class-of-service and quality-of-service includes allocating bandwidth for guaranteed transmission rates requested by the cable modems. The handling and balancing requires significant computational and computer resources on the cable modem termination system. The cable modem termination system uses complex software that is not easily adaptable to new or additional class-of-service or quality-of-service parameters. In addition, multiple cable mode
Budinger Daniel M.
Fijolek John G.
Gilbert Irene M.
Jain Narij
Robinson Phillip T.
3Com Corporation
Lim Krisna
McDonnell & Boehnen Hulbert & Berghoff
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