Cable modem system

Details Cable modem system Cable modem system

1999-12-23

2003-11-18

Thompson, Marc D. (Department: 2142)

Electrical computers and digital processing systems: multicomput

Network computer configuring

C709S221000, C709S222000, C709S250000

Reexamination Certificate

active

06651092

ABSTRACT:

BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention generally relates to a cable modem system comprising a mechanism which dynamically assigns an Internet protocol (IP) address in response to a client request. More particularly, the present invention relates to a cable modem system in which an IP address-assigning mechanism assigns a private address and a global address according to a classification of a requesting client.
II. Background and Material Information
Cable modem systems, which enable digital communication over a coaxial cable network for cable television (CATV), have recently become widespread. The cable modem system realizes high-speed computer communication using the same signal that a regular television system uses, i.e., a radio frequency (RF) signal. In the cable modem system, both television service and digital communication service can be provided to a member via the same cable.
FIG. 3
is an exemplary block diagram showing the configuration of a cable modem system.
FIG. 4
is an exemplary block diagram showing the configuration of a cable modem (CM).
FIG. 5
is showing exemplary communication between two CMs connected to the same cable.
As shown in
FIG. 3
, a cable modem system mainly comprises a cable modem terminate system (CMTS)
302
, a CM
304
, and a CATV cable
306
via which CMTS
302
and CM
304
are connected to each other. CMTS
302
receives data from a provider's network
308
, which conforms to a standard for local area networks (LAN) such as 100BASE-T or asynchronous transfer mode (ATM), and transforms the data into an RF signal and vice versa. CM
304
is generally located at a home, for instance, to realize a small office/home office (SOHO). CM
304
is connected to a user computer such as personal computer or workstation (PC/WS)
310
via a user's network
312
conforming to a standard such as 10BASE-T or 100BASE-T.
CMTS
302
and CM
304
enable unsymmetrical high-speed communication in the cable modem system, i.e., communication from CMTS
302
to CM
304
(hereinafter referred to as “downstream communication”) at a predetermined rate, e.g., 10 Mbps-40 Mbps and communication from CM
304
to CMTS
302
(hereinafter referred to as “upstream communication”) at a predetermined rate, e.g., 1 Mbps-10 Mbps. A plurality of CMs
304
a
-
304
b
connected to single CATV cable
306
share both the downstream frequency (F
1
) and the upstream frequency (F
2
) on CATV cable
306
.
As shown in
FIG. 4
, CM
304
a
comprises an RF receiver
402
and an RF transmitter
404
. CM
304
a
assists PC/WS
310
a
in communicating with another user computer
310
c
connected to another CM
304
b
, however, CM
304
a
can not receive an RF signal directly from CM
304
b
because of the difference in frequencies between the downstream communication and the upstream communication.
Therefore, as shown in
FIG.5
, CMTS
302
comprises a relay unit
502
which receives a data frame sent from CM
304
a
and sends it to another CM
304
c
. Relay unit
502
enables the CATV cable
306
to be treated in the same way as an ethernet LAN and allows the application of techniques used for a regular LAN.
Originally, CM
304
just needed a media access control (MAC) address and did not need an IP address. However, recently, even a hub or a modem has become a mechanism conforming to a network management protocol such as simple network management protocol (SNMP), which requires an IP address, so that a provider's SNMP server can grasp conditions of the hub or the modem and alter their definition information.
Single CM
304
is usually supposed to be assigned to single user. For an operator to manually assign those IP addresses would be a hard task. Therefore, a mechanism conforming to a dynamic host configuration protocol (DHCP) is usually used. A server which comprises the mechanism is called DHCP servers and it dynamically assigns an IP address to a client, such as CM
304
or PC/WS
310
, in response to a request from the client.
In the case of a huge cable modem system, the number of CMs
304
is very large, e.g., thousands through ten thousands. Moreover, because CM
304
is usually kept working without being shut off the power, many IP addresses are capable of being held by most CM
304
s. Therefore, more IP addresses are required so that the system can efficiently work in this situation.
However, the number of IP addresses is limited and an exhaustion of IP addresses has turned into a grave issue. Therefore, it is difficult to own many IP addresses and costly for a company.
An IP address for accessing to the Internet is also called a “global address”. Originally, an “IP address” meant an address used in an IP network, one of which is the Internet. However, “IP address” is now often used to mean just an address used for the Internet. To avoid confusion, an IP address for accessing to Internet will be referred as to “global address” and an IP address other than a “global address” will be referred to as a “private address” in the following.
SUMMARY OF THE INVENTION
In view of the foregoing, the present invention is directed to a system and method for managing an assignment of IP addresses in a cable modem system that substantially obviates one or more of the problems due to limitations and disadvantages of the past approaches.
In accordance with an aspect of the present invention, as embodied and broadly described, the present invention is directed to a cable modem system. The system comprises at least one cable modem, at least one user computer connected to the cable modem, a CMTS, a cable via which the cable modem and the CMTS are connected, and means connected to the CMTS for assigning an IP address of a specific kind according to the classification of a client in response to a request for an IP address from the client.
In accordance with another aspect of the present invention, there is provided a method for managing an assignment of IP addresses in a cable modem system. The method comprises issuing a request for an IP address by a client and issuing an IP address of a specific kind according to the classification of the client by a server.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. Further features and/or variations may be provided in addition to those set forth herein. For example, the present invention may be directed to various combinations and subcombinations of the disclosed features and/or combinations and subcombinations of several further features disclosed below in the detailed description.


REFERENCES:
patent: 5884024 (1999-03-01), Lim et al.
patent: 6009103 (1999-12-01), Woundy
patent: 6023464 (2000-02-01), Woundy
patent: 6101182 (2000-08-01), Sistanizadeh et al.
patent: 6178455 (2001-01-01), Schutte et al.
patent: 6212563 (2001-04-01), Beser
patent: 6240464 (2001-05-01), Fijolek et al.
patent: 6370147 (2002-04-01), Beser
patent: 6405253 (2002-06-01), Schutte et al.
patent: 6421728 (2002-07-01), Mohammed et al.
patent: 6466986 (2002-10-01), Sawyer et al.
Droma, R. Dynamic Host Configuration Protocol. RFC 2131. Mar. 1997.*
Srisuresh, P.Load Sharing using IP Network Address Translation. RFC 2391.Aug. 1998.*
Egevang, K.The IP Network Address Translator.RFC 1631. May 1994.*
Droms, “Dynamic Host Configuration Protocol,” Bucknell University (Oct. 1993), pp. 1-39.

Affiliated with

Also associated with

Rating

Cable modem system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Cable modem system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cable modem system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3144936