Electrical computers and digital processing systems: multicomput – Network-to-computer interfacing
Reexamination Certificate
1998-02-04
2001-05-29
Breene, John (Department: 2177)
Electrical computers and digital processing systems: multicomput
Network-to-computer interfacing
C709S238000, C370S351000
Reexamination Certificate
active
06240464
ABSTRACT:
FIELD OF INVENTION
The present invention relates to communications in computer networks. More specifically, it relates to a method and system for managing addresses for network host interfaces.
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 30+ Mbps.
The Internet, a world-wide-network of interconnected computers, provides multi-media content including audio, video, graphics and text that requires a large bandwidth for A- 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 30+ Mbps available on a coxial 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., U.S. Robotics Corporation of Skokie, Ill., 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 “downstream” data rate of 30+ Mbps, which is a much larger data rate than can be supported by serial telephone line used over a modem.
However, most cable television networks provide only uni-directional cable systems, supporting only a “downstream” 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, such as a Public Switched Telephone Network provided by AT&T and others, (i.e., “telephony return”) 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 a cable modem termination system, a cable television network, a public switched telephone network, a telephony remote access concentrator, a cable modem, customer premise equipment (e.g., a customer computer) 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 responses data packets to the cable modem, which sends response data packets upstream via the 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. The data-over-cable system with telephony return provides transparent Internet Protocol (“IP”) data traffic between customer premise equipment, a cable modem and the data network (e.g., the Internet or an intranet). As is known in the art, IP is a routing protocol designed to route traffic within a network or between networks.
When a cable modem used in the data-over-cable system with telephony return is initialized, it will make a connection to both the cable modem termination system via the cable network and to the telephony remote access concentrator via the public switched telephone network. If the cable modem is using telephony return, it will acquire telephony connection parameters on a downstream connection from the cable modem termination system and establish a Point-to-Point Protocol (“PPP”) connection to connect an upstream channel to the telephony remote access concentrator. As is known in the art, PPP is used to encapsulate datagrams over a serial communications link. After a PPP connection is established, the cable modem negotiates a telephony IP address with the telephony remote access concentrator. The telephony IP address allows the customer premise equipment to send IP data packets upstream to the telephony remote access concentrator via the public switched telephone network to the data network.
The cable modem also needs to make an IP connection to the cable modem termination system so that IP data received on the cable modem termination system from the data network can be forwarded downstream to the customer premise equipment via the cable network and the cable modem. In one embodiment of the present invention, the cable modem establishes an IP address with the cable modem termination system through the telephony remote access concentrator using a Dynamic Host Configuration Protocol (“DHCP”). As is known in the art, DHCP provides configuration parameters for network host interfaces (e.g., IP interfaces) to network hosts.
There are several problems with using DHCP to configure network host interfaces such as IP interfaces available on the cable modem termination system. DHCP was not originally intended for use in configuring a system like the data-over-cable system with telephony return. In the data-over-cable system with telephony return, a cable modem desires to establish an IP connection with the data network with an IP interface available on the cable modem termination system. However, the cable modem only has a downstream connection from the cable modem termination system. The cable modem has an upstream connection to the telephony remote access concentrator via the public switched telephone network. However, the telephony remote access concentrator does not have any DHCP servers for receiving DHCP requests. The cable modem termination system has DHCP servers for receiving DHCP requests for network host interfaces, but it cannot be accessed directly by a cable modem in a data-over-cable system with telephony return.
The cable modem desires to send a DHCP-discover message to the telephony remote access concentrator via the public switched telephone network and have the telephony remote access concentrator forward the message to a DHCP server associated with network host interfaces available on the cable modem termination system. However, there is currently no way to accomplish the connection scenario with DHCP since the telephony remote access concentrator has no mechanism to forward DHCP-discover messages to DHCP servers associated with the cable modem termination system. The DHCP servers are not directly addressable by a cable modem since the cable modem has only a downstream connection from the cable modem termination system via the cable network.
As a result, the cable modem cannot create a transparent IP data path using DHCP to receive IP data packets from the data network on a downstream data channel on the cable network from a network host interface available on the cable modem termination system and send IP data packet responses back to the data network upstream though the telephony remote access concentrator via the public switched telephone system.
A network host interface address is obtained for a cable
Beser Nurettin B.
Fijolek John G.
3Com Corporation
Breene John
Lesavich Stephen
McDonnell & Boehnen Hulbert & Berghoff
Robinson Greta L.
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