WO2002035374A1

WO2002035374A1 - Utilization of connection admission control check on physical interface connections bearing traffic from multiple internet service providers

Info

Publication number: WO2002035374A1
Application number: PCT/US2001/028750
Authority: WO
Inventors: Thomas J. Cloonan; William P. Ward
Original assignee: Arris International, Inc
Priority date: 2000-09-12
Filing date: 2001-09-12
Publication date: 2002-05-02
Also published as: AU2001290921A1

Abstract

A cable modem termination system (200) that uses a connection admission control process to monitor a physical interface connection to the Internet for bandwidth usage. Internet service providers (301 and 302) are coupled to the cable mode termination system's physical interface port (201) through the Internet. Each of the Internet service providers are assigned a predetermined bandwidth based on the quantity of subscribers assigned to each Internet service provider. If the connection admission control process determines that an Internet service provider is over using the assigned bandwidth, that Internet service provider is given a message indicating this over usage. The connection admission control process is also used to monitor the bandwidth usage of cable modem channels and physical interface or other types of physical interface channels.

Description

UTILIZATION OF CONNECTION ADMISSION CONTROL CHECK ON

PHYSICAL INTERFACE CONNECTIONS BEARING TRAFFIC FROM

MULTIPLE INTERNET SERVICE PROVIDERS FIELD OF THE INVENTION

The present invention relates generally to cable data communications. Particularly, the present invention relates to checking of the bandwidth of a data link in a cable modem environment.

DESCRIPTION OF THE RELATED ART

In order to provide more service to their subscriber base, cable television companies are offering access to the Internet through their cable modem (CM) boxes. The benefits in using the cable companies instead of a dial-up Internet Service Provider is multiple services under one bill, always-on access and, in some cases, higher speed access. In order to provide their customer's with Internet access, the cable companies use some of the 50-800 MHz spectrum typically set aside for their television channels to provide the bandwidth required for the data transfers. A typical cable system has the bandwidth to provide 100 television channels to its subscribers. Each NTSC television signal requires 6 MHz of bandwidth. In order for a cable subscriber to access the Internet through their cable television provider, the subscriber must have a CM. The CM is similar to the Cable Modem Termination System (CMTS) equipment required at the cable company's headquarters, except for the greater size required at the headquarters. This is to accommodate a greater number of signals than is required by the home modem. The home CM box and the CMTS use well-known Ethernet frames to communicate between them. The cable system, however, uses different modulation scheme, Quadrature Amplitude Modulation (QAM), than is normally used in an Ethernet scheme.

Using QAM, the downstream (from the cable company equipment to the home CM) data rate is in the range of 30-40 Mbps for each 6 MHz channel. This can typically accommodate between 500 and 2000 subscribers. The more subscribers that the cable company tries to fit in that spectrum, the lower the bandwidth available for each subscriber.

The upstream data flow is different and more complex. In the past, cable companies did not have to worry about providing bandwidth for the customer to communicate in the upstream direction. Pay-per-view movies and sports events, however, required this ability. The cable companies, therefore, set aside the 5-42 MHz spectrum to allow the home CM to communicate in the upstream direction. The cable companies now use this 5-42 MHz spectrum to provide the necessary upstream access to the Internet from the home CM.

FIG. 1 illustrates a typical prior art CMTS block diagram. The CMTS typically is comprised of a cable interface card (101) to provide the interface signals and modulation to the signals transmitted to the home modem. An Ethernet card (1 10) interfaces the CMTS to the Internet by providing appropriate timing, control, and data signal formats for the Internet. A buffer circuit (105) between the cable interface card (101) and Ethernet card (101) stores data in both the upstream and downstream directions when the processing in either the cable interface card or the Ethernet card is slower than the incoming data.

The Random Early Discard scheme samples the depth (amount of memory space used) of the buffer (105) and randomly drop packets to prevent the buffer from overflowing. Using this scheme, a cable subscriber may not lose any data or may lose a lot of data, depending on a purely random occurrence.

Each cable company typically has a contract with one Internet Service Provider (ISP) in order to provide Internet service to their cable customers. Presently, two ISPs exist that provide the majority of ISP service to the subscribers of cable companies. This presents an open access problem since both ISPs (in addition to any future ISPs) would like to provide service to as many customers as possible. Additionally, cable customers would like to have the option of choosing between multiple ISPs instead of being stuck with the one choice of the cable company. There exists an unforeseen need to permit a cable company to operate with multiple ISPs and thus allow its customers to select their own choice of ISP.

SUMMARY OF THE INVENTION The present invention encompasses a process for utilizing a connection admission control process to determine a bandwidth of a data connection in a cable modem termination system. The cable modem termination system is comprised of an Ethernet port (or other type of connection port) that is coupled to the Internet. A plurality of Internet service providers are coupled to the cable modem termination system through the Internet. A plurality of cable modems are coupled to the cable modem termination system through cable modem channels.

The connection admission control process determines a data bandwidth that each of the plurality of Internet service providers is using through the Ethernet port. If one of the Internet service providers is over using the assigned data bandwidth, an error message is generated indicating to that Internet service provider that it should either cut back on bandwidth usage or obtain additional bandwidth.

The process determines the over usage by subtracting the total bandwidth used by all of the subscribers of a particular Internet service provider from the total bandwidth assigned to that particular Internet service provider. This bandwidth checking process is performed in both the upstream and downstream directions on the Ethernet port and the upstream and downstream directions on the cable modem channels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of a typical prior art cable modem termination system.

FIG. 2 shows a block diagram of a cable modem termination system apparatus of the present invention. FIG. 3 shows a block diagram of a cable modem termination system coupled to the

Internet in accordance with the present invention.

FIG. 4 shows a block diagram of a cable modem termination system operating in accordance with the process of the present invention.

FIG. 5 shows a flowchart of a process of the present invention that utilizes a connection control admission process to determine Ethernet resources.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention provides cable customers the option of using their choice of ISP. By performing a connection admission control check on the Ethernet port with the Internet, the process of the present invention determines and subtracts the subscribers' bandwidth requirements during the registration process. This provides the cable modem termination system (CMTS) with the knowledge of the required bandwidth to support a predetermined number of subscribers.

FIG. 2 illustrates the preferred embodiment of the CMTS apparatus of the present invention. While the present invention will be described as applying to a cable modem environment, the process of the present invention utilizing the connection admission control check can be used in other systems requiring a resource check ofthe bandwidth available to multiple users.

The CMTS apparatus (200) of FIG. 2 is comprised of a cable interface (201) that is coupled to a buffer circuit (205). In the preferred embodiment, the buffer circuit (205) is coupled to an Ethernet interface (210). In alternate embodiments, other types of physical interfaces can be used. In the preferred embodiment, each ofthe individual circuits (201 , 205, and 210) reside physically on separate circuit boards. In alternate embodiments, any circuits having substantially the same function can reside on one circuit board or even one integrated circuit. In other words, the present invention is not limited to three separate circuit boards.

The cable interface (201) is responsible for interfacing the CMTS to the home cable mode apparatus. The cable interface (201) also provides the functions of modulation and demodulation.

The cable interface circuit is comprised of a downstream packet flow path and an upstream packet flow path. The downstream packet flow path is comprised of a data throughout monitor (220) that is coupled to a flow limiter (215). The data throughput monitor (220) has an input that is coupled to the buffer circuit (205) from which the data packets flow and a feedback from the upstream path. The feedback from the upstream path is to allow a first CM to talk with other CMs. The data throughput monitor (220) has the task of determining the rate of data packet flow.

In the preferred embodiment of the CMTS, the downstream data packet flow rate is typically either 30 or 40 Mbps for each 6 MHz channel, using QAM techniques. Alternate embodiments use other flow rates. The cable company decides which data packet flow rate depending on the outcome desired by the company. The lower data rate is less susceptible to noise while the higher data rate can include more data per unit of time for the customers. The data packet flow rate signal is fed into the flow limiter (215). This signal controls the flow limiter function. If the flow is greater than a predetermined level, T_mav, the data packet flow can be limited. The flow limiter (215) reduces the data rate by dropping packets until the flow is reduced to below T_max. Another input to the flow limiter (215) is the "limiting type" input. This control input is set by the cable company depending on how strictly they wish a customer to adhere to the rules. If the "limiting type" input is set to "soft-limiting," the flow limiter (215) allows the data rate to go above the set data rate by a predetermined amount without dropping any packets. Some cable companies may strictly limit a customer to T_max. In this case, the

"limiting type" control input is set to "hard-limiting". If the data rate goes over the set hard limit, the flow limiter (215) drops any packets that force the customer to exceed T_max. The output of the flow limiter (215) is coupled to the cable that runs to the customers' cable modems. The output of the flow limiter (215) is input to the modulator (255). This block

(255) performs the QAM needed to transmit the data to the CMs.

The upstream data path is comprised of a demodulator and Filter (260) that converts the QAM signal into data bits in order to be processed by the other blocks in the upstream path. The demodulated data bits are input to a data throughput monitor (225) that is coupled to the upstream port from the customer's CM. This data throughput monitor (225) has the same functionality as the downstream monitor (220) of monitoring the data rate but in the upstream direction to the Internet.

In the preferred embodiment, the upstream data rate can be in the range of 320 kbps to 10.24 Mbps. Alternate embodiments use other rates. The upstream data throughput monitor (225) is coupled to a flow limiter (230).

This flow limiter has similar functionality to the flow limiter (215) in the downstream path. The upstream path flow limiter (230) has the data rate input from the data throughput monitor (225) as well as the "limiting type" control input that, in the preferred embodiment, is set to either "hard-limiting" or "soft-limiting" depending on the cable company rules. As in the downstream flow limiter (215), the upstream flow limiter. depending on the "limiting type" input, drops all packets that force the customer to exceed

' max-

The upstream path further comprises a congestion control block (235) that is coupled to the upstream data path out of the flow limiter (230). The data packets from the upstream data path flow through the congestion control block (235) to the buffer circuit (205). The function of the congestion control block (235) is to drop packets when the buffer depth is reaching a maximum point. By dropping the packets before they reach the buffer, the buffer will not overflow.

In order to accomplish the task of congestion control, the congestion control block (235) has control inputs that are used to determine when to drop packets and which packets to drop. In the preferred embodiment, these control inputs include the data rate signal from the upstream data throughput monitor (225), a buffer depth signal from the buffer (205), and a priority signal.

The data rate signal from the upstream data throughput monitor (225), as described above, quantizes the data rate and feeds that value to the congestion control block (235). The buffer circuit depth signal from the buffer circuit (205) instructs the congestion control block (235) as to the depth of the buffer. In other words, if the buffer (205) is 75% full, the buffer depth signal instructs the congestion control block (235) of this.

The priority signal that is input to the congestion control block (235) informs the congestions control of the priority of each packets. This is important in determining which packets to drop.

A group of packets is assigned a priority based on the customer's level of service plan. If the customer has signed up for the basic service plan and paid the smallest fee for the most basic service, his packets are assigned a low priority. This priority is embedded in a packet identification that is assigned to the group of packets and is decoded when the group of packets enters the cable interface.

If the customers has signed up for the premium service plan with the cable company, his packets are assigned the highest priority. If the customer has signed up for any service plans that are in between the premium and the basic plans, this priority is also assigned to each packet. As described before, the priority is added to the packet identification for a particular group of packets. A customer may also decide to dynamically change his service level for a given session. In this case, different packet groups from that particular customer will have different priorities assigned to different packet identifications.

The buffer circuit (205) stores the packets until the Ethernet circuit (210) has time to process that packet. The packets are fed from the buffer circuit (205) to the Ethernet circuit (210) as more processing time is freed up.

The downstream path of the Ethernet circuit (210) is comprised of a data throughput monitor (250) that is coupled to the connection to the Internet. This monitor (250) provides substantially the same function as the previously described data throughput monitors on both the upstream and downstream paths.

The data packets from the Internet flow from the data throughput monitor (250) to the Ethernet's circuit flow limiter (245). This flow limiter (245) has substantially the same functionality as the above described flow limiters. This flow limiter also has the same inputs as described previously; the quantized data rate and the "limiting type" control input.

The data packets flow from the flow limiter (245) to the congestion control block (240). As in the upstream congestion control block (235), the Ethernet's downstream congestion control block (240) has the three control inputs to determine which packets to drop: the quantized data rate, the buffer depth signal, and the packet priority signal. The congestions control block then drops a particular packet based on these control signals.

The downstream data flows from the congestion control block to the buffer circuit (205). The buffer circuit (205) stores the packets until the cable interface circuit has the processing time to work on additional packets.

The buffer circuit (205) is comprised of 128 MB of RAM, in the preferred embodiment. Alternate embodiments use other values of RAM or even other types of memory instead of RAM. The alternate types of memory include hard drives or other types of temporary memory.

The cable interface card (201 ) and the Ethernet interface card (210) are each controlled by an on-board controller (270 and 280 respectively). In the preferred embodiment, these are central processing units with memory that control each interface and communicate with the other controllers in the system. The controllers (270 and 280) distribute the connection admission control process of the present invention.

It is possible for the connection admission control process to determine the bandwidth requirements for a particular subscriber, because each subscriber must initially sign up for a pre-specified service level (which can be comprised of multiple packet streams or service flows) when they register for a service level agreement. There is a distinct bandwidth range (between T_max and T_mιn) associated with each of the service flows that a particular subscriber will be using. Thus, a subscriber's bandwidth requirements are known before the subscriber even begins to transport data across the CMTS. Whenever a subscriber activates one or more of their service flows by powering up their cable modem or by interacting with a service level agreement server, a weighted value based on the bandwidth range values (T_maX and T_mln) that are themselves associated with that particular service flow is used by the connection admission control process. The connection admission control process uses this weighted value to determine if there is adequate bandwidth remaining on the shared resources that will be used by the service flows.

The connection admission control process stores a set of credits for each of the shared resources that will be used by the activated service flows, and it decrements the credit count by the associated weighted value whenever a service flow is enabled. The connection admission control process increments the credit count by the associated weighted value whenever a service flow is disabled. If the credits are depleted down to zero, then the connection admission control process can prevent any future service flows from being set up on the shared resource. In an alternate embodiment, the connection admission control process will allow future service flows to be set up even if the resource credits are depleted down to zero, but it will generate an error message to the network management system indicating that the shared resource is being over-subscribed.

In an alternate embodiment, the controller functions that are performed by the individual controllers (270 and 280) are contained in a single controller that controls the entire CMTS. In such an embodiment, the controller, including the memory, may be located on one of the interface cards or may comprise a separate controller card. In such an embodiment, the connection admission control process would be provided by this controller card.

Most of the functions illustrated in FIG. 2 may be implemented in various ways. These functions can be performed in software by a processor or multiple processors performing each function. Each function can also be implemented in discrete logic hardware, a digital signal processor, or some other form of programmable logic.

FIG. 3 illustrates a block diagram of the system of the present invention. The system is comprised of a CMTS (200) as described from FIG. 2. The CMTS is coupled to the Internet (305) through the Ethernet ports. The ISPs are also coupled to the Internet (305). FIG. 3 only illustrates two ISPs: ISP1 (301) and ISP2 (302). In alternate embodiments, additional ISPs may be added and still be encompassed by the present invention.

The ISPs of the present invention are of the type that provide "always on" Internet service to subscribers. As an example, a company such as ROADRUNNER provides this type of service.

The CMTS is also coupled to a plurality of CMs (310). For clarity, only one CM (310) is illustrated in FIG. 3. The CMTS may accommodate 500-1000 subscriber CMs depending on the quality of service desired by the cable company. The present invention is not limited to a certain quantity of CMs. A CM has substantially the same functional block diagram as the CMTS. The main difference between the two is that the CMTS is designed to handle hundreds of subscribers whereas the CM is designed for single home use.

The CM (310) is coupled to the subscriber's personal computer (3 15). In the preferred embodiment, this PC (315) is a computer that runs operating systems such as WINDOWS or MACINTOSH. Alternate embodiments couple the CM (310) to personal digital assistants or other types of smaller computers. FIG. 3 also illustrates only one PC (3 15) being coupled to the CM (3 10). Alternate embodiments are not limited to a single PC.

FIG. 4 illustrates an example of the system of FIG. 3 in operation. For purposes of the illustration of operation, a total bandwidth of 100 Mbps in the upstream direction and a total bandwidth of 100 Mbps in the downstream direction is assumed for both the Ethernet connection and the connections between the CMTS and the CMs. Alternate embodiments have other data rates that can be either greater than or less than the 100 Mbps ofthe present invention.

When a subscriber signs up for data service with the company selling the cable modem service, the subscriber signs up for a certain bandwidth of data service. The subscriber also chooses his ISP at this time. The subscriber's choices of bandwidth and ISP are stored at the cable company's main office or other location where the CMTS is located.

The Ethernet resource between the Internet and the CMTS must be shared fairly between the two ISPs (440 and 450). This is accomplished by each ISP renting a percentage of the bandwidth of the upstream and downstream directions. The number of subscribers that the ISP has determines the percentage of the bandwidth required by that ISP. The more subscribers signed up with a certain ISP, the larger the bandwidth that the ISP must rent in order to provide service to those subscribers. As an example, ISP1 (440) may rent 60%, which is 60 Mbps, in both the upstream and downstream directions while ISP2 (450) rents 30% or 30 Mbps in both the upstream (410) and downstream (405) directions. This leaves 10% or 10 Mbps in both directions (405 and 410) for future expansion to additional ISPs.

In one embodiment, the ISPs rent the same bandwidth in both the upstream (410) and downstream (405) directions. Alternate embodiments enable the ISPs to rent one bandwidth for the upstream (410) and a second, different bandwidth, for the downstream (405) direction.

In order to ensure that the cumulative bandwidth (credit) associated with a particular ISP not over-subscribed, the bandwidth that is being used by each subscriber is subtracted from the total available bandwidth. If the result shows that a particular subscriber's bandwidth has totally depleted the credit for a particular ISP, then the subscriber should get an error message and should not be allowed access to the ISP. An error message is also sent to the network management system. In an alternate embodiment, the subscriber who has depleted the credit for a particular ISP is allowed access to the ISP and an error message is also sent to the network management system indicating that the ISP's bandwidth has been over-subscribed. This bandwidth check is performed by the connection admission control (CAC) process in the CMTS (415). This check is performed, in the preferred embodiment, when the subscriber turns on his or her service with the cable company (which is typically done during the ranging and registration process in the CMTS). The CAC process check both the upstream and the downstream cable channel resource to verify that enough bandwidth exists to add the customer. Every time that the subscriber's CM goes through the registration process, the CAC process must subtract the bandwidth for which the subscriber signed up from the available cable channel resource.

As an example of the CAC check operation of the present invention, in this embodiment the subscriber has signed up for a bandwidth of 2 Mbps upstream and a bandwidth of 4 Mbps downstream. This bandwidth is designated as the "Throughput minimum," hereinafter referred to as T_mιn The customer typically signs up for a T_mm(Up), the upstream bandwidth to the ISP, and T_mj_π(_down), the downstream bandwidth from the ISP.

When the CAC turns on and performs a check of the CM channels, it deducts 2 Mbps from the 10 Mbps of total upstream bandwidth leaving a credit of 8 Mbps. Similarly, the downstream bandwidth of 4 Mbps for which the subscriber signed up is deducted from the 30 Mbps of total downstream bandwidth leaving a credit of 26 Mbps.

The CAC process performs a similar process with the Ethernet port. In this case, the CAC process deducts 2 Mbps from the 100 Mbps upstream bandwidth leaving a credit of 98 Mbps. The 4 Mbps is deducted from the downstream bandwidth at the Ethernet port leaving a 96 Mbps credit.

The CAC process also performs a similar process with ISPs that are associated with a particular Ethernet port. In this case, assume that the subscriber is associated with ISP1 , and assume ISP1 has rented 60 Mbps of the Ethernet connection in both the upstream direction and downstream direction. The CAC process deducts 2 Mbps from the 60 Mbps upstream bandwidth leaving a credit of 58 Mbps. The 4 Mbps is deducted from the 60 Mbps downstream bandwidth leaving a 56 Mbps credit.

The process of the present invention is illustration in FIG. 5. The process begins with the CM ranging and registering with the cable system according to the Data Over Cable Service Interface Standard (DOCSIS). The DOCSIS registration process is well known in the art. During the ranging and registration process (step 501 ), the CM and the CMTS go through a ranging process to get the CM on a channel that is acceptable to the CMTS. The ranging step also includes determining the power level required by the CMTS from the CM. The CM next goes through the registration process (step 502) to get the information required to be an Internet Protocol (IP) host, such as the IP address, from the Dynamic Host Configuration Protocol (DHCP) server. During this registration process, the CM also downloads, from the Trivial File Transfer Protocol (TFTP) server, the service level and other service information for that particular CM. During the registration process, the CMTS also checks the amount of bandwidth for which the customer has signed up. As described above, this bandwidth is a weighted value based on the bandwidth range values (T_max and T_m;_n). Oftentimes, the weighted values if merely set to be T_mm value in both the upstream and downstream directions.

The connection admission control (CAC) process then turns on (step 505). The CAC needs to perform six checks (step 510); a check of the bandwidth at the Ethernet port in both the up and down directions, a check of the bandwidth at the cable modem port in both the up and down directions, and a check of the bandwidth for the ISP (pre-selected by the customer) in the Ethernet port in both the up and down directions. These checks are described above as referenced to the example illustrated in FIG. 4. The process then checks to determine if either the subscriber or the ISP are at their credit limits for bandwidth (step 515). As described above with reference to FIG. 4, this occurs if either entity uses more bandwidth than what they have subscribed or rented.

If either the subscriber or the ISP has gone beyond their credit limit, an error message is generated informing the network management system of the problem (step 520). In another embodiment, the subscriber is also denied service when the credit limit is used up.

In summary, the process and system of the present invention provide benefits for both ISPs and cable company subscribers. The connection administration control process checks the Ethernet port of the CMTS to determine if the bandwidth rented by an ISP is exceeded by the addition of additional subscribers to that ISP. This allows the cable company to offer services from more than one ISP to each of its cable subscribers.

Claims

WE CLAIM:

1 . A method for utilizing a connection admission control process to determine a bandwidth of a data connection in a cable modem termination system having a physical interface port, the method comprising the steps of: coupling the physical interface port to a plurality of Internet service providers; providing a predetermined provided data bandwidth to each of the plurality of Internet service providers; the connection admission control process determining a used data bandwidth for eaϋh of the plurality of Internet service providers on the physical interface port; and generating a message indicative of a difference between the provided data bandwidth and the used data bandwidth.

2. The method of claim 1 wherein the Internet service providers are coupled to the physical interface port through the Internet and the physical interface port is an

Ethernet port.

3. The method of claim 1 and further including the step of coupling the cable modem termination system to a plurality of cable modems through cable modem channels.

4. The method of claim 1 and further including the step of the connection admission control process determining a predetermined bandwidth of the cable modem channels.

5. The method of claim 1 wherein the message includes an error message indicating a data bandwidth deficit.

6. The method of claim 1 wherein the message includes a message requesting additional data bandwidth.

7. The method of claim 3 and further including the steps of: the cable modem registering with the cable modem termination system; and the cable modem ranging with the cable modem termination system.

8. The method of claim 1 wherein the step of the connection admission control process determining a used data bandwidth for each of the plurality of Internet service providers on the physical interface port includes the connection admission control process determining a used data bandwidth in both an upstream direction and a downstream direction.

9. A method for utilizing a connection admission control process to determine a bandwidth of a data connection in a cable modem termination system having a physical interface port, the method comprising the steps of: coupling the cable modem termination system to a plurality of modems through cable modem channels; coupling the physical interface port to a plurality of Internet service providers through the Internet; assigning a predetermined provided data bandwidth to each of the plurality of

Internet service providers based on a predetermined number of cable subscribers that have subscribed to that particular Internet service provider; the connection admission control process determining a used data bandwidth in an upstream data direction for each of the plurality of Internet service providers on the physical interface port; the connection admission control process determining a used data bandwidth in a downstream data direction for each of the plurality of Internet service providers; generating a message if a difference between the provided data bandwidth and the used data bandwidth in the upstream data direction indicates over usage by an Internet service provider of the plurality of Internet service providers; and generating a message if a difference between the provided data bandwidth and the used data bandwidth in the downstream data direction indicates over usage by an Internet service provider of the plurality of Internet service providers.

10. The method of claim 9 wherein the step of generating a message includes generating an error message indicating that the Internet service provider that has over used the predetermined bandwidth.

1 1. The method of claim 9 wherein the step of generating a message includes generating a bandwidth purchase message that provides the Internet service provider that has over used the predetermined bandwidth with the option for obtaining additional bandwidth.

12. A method for utilizing a connection admission control process to determine a bandwidth of a data connection in a cable modem termination system having a plurality of cable modem channels, each cable modem channel coupled to a cable modem, the method comprising the steps of: providing a predetermined provided data bandwidth to each of the plurality of cable modem channels; the connection admission control process determining a used data bandwidth for each channel of the plurality of cable channels; and generating a message indicative of a difference between the provided data bandwidth and the used data bandwidth.

13. The method of claim 12 wherein the message includes an error message indicating a data bandwidth deficit.

14. The method of claim 12 wherein the message includes a message requesting additional data bandwidth.

15. The method of claim 12 and further including the steps of: each of the plurality of cable modems registering with the cable modem termination system; and each of the plurality of cable modems ranging with the cable modem termination system.

16. A system for enabling a cable modem subscriber to choose between a plurality of Internet service providers, the system comprising: a cable modem termination system comprising a plurality of cable modem channel ports and a physical interface port, the cable modem termination system additionally comprising at least one controller for executing a connection admission control process for checking a bandwidth used by the physical interface port and a bandwidth used by each of the plurality of cable modem channel ports; a plurality of cable modems, each cable modem coupled to a cable modem channel port of the plurality of cable modem channel ports; and the plurality of Internet service providers coupled to the cable modem termination system.

17. The system of claim 16 wherein the plurality of Internet service providers are coupled to the cable modem termination system through the Internet and the physical interface includes an Ethernet port.

18. The system of claim 16 wherein the connection admission control process subtracts an actual bandwidth used by a first Internet service provider of the plurality of Internet service providers in order to determine the bandwidth used by the physical interface port.

19. The system of claim 16 wherein the at least one controller comprises a single controller for controlling the cable modem termination system and executing the connection admission control process.

20. The system of claim 16 wherein the at least one controller comprises a plurality of controllers for controlling the cable modem termination system and executing the connection admission control process in a distributed manner.

21. A cable modem termination system that provides data service to a plurality of cable modem subscribers, each subscriber having a cable modem, the cable modem termination system comprising: a physical interface coupled to the Internet, the physical interface comprising a controller that executes a connection admission control process that manages a bandwidth of the Internet interface; a buffer device, coupled to the physical interface, for temporarily storing data from the plurality of cable modem subscribers and from the Internet; and a cable interface coupled to the buffer device and to the plurality of cable modems, each through a cable modem channel, the cable interface comprising a controller that executes the connection admission control process to manage a bandwidth of the cable modem channels.

22. A cable modem termination system that provides data service to a plurality of cable modem subscribers, each subscriber having a cable modem, the cable modem termination system comprising: a physical interface coupled to the Internet, the physical interface comprising circuitry for managing a flow of data to and from the Internet; a buffer device, coupled to the physical interface, for temporality storing data from the plurality of cable modem subscribers and from the Internet. a cable interface coupled to the buffer device and to the plurality of cable modems, each through a cable modem channel, the cable interface comprising circuitry to manage a flow of data to and from the cable modem channels; and a controller for executing a connection admission control process that manages the bandwidth of the flow of data to and from the cable modem channels, the controller additionally managing the bandwidth of the flow of data to and from the Internet.