Cable television networks such as those provided by Comcast Cable Communications, Inc., of Philadelphia, Pa., Cox Communications of Atlanta Ga., Time-Wamer 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 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 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., Cisco Corporation of San Jose, Calif., Scientific-Atlanta, of Norcross, Ga. 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 30+ Mbps, which is a much larger data rate than can be supported by a modem used over a serial telephone line.
Many cable television networks provide bi-directional cable systems, in which data is sent “downstream”, from a “headend” to a customer, as well as “upstream”, from the customer back to the headend. The cable system headend is a central location in the cable television network and, further, is responsible for sending cable signals in the downstream direction and receiving cable signals in the upstream direction. An exemplary data-over-cable system with RF return typically includes customer premises equipment such a customer computer, a cable modem, a cable modem termination system, a cable television network, and a data network such as the Internet.
Some cable television networks provide only uni-directional cable systems, supporting only a “downstream” data path, which provides a path for flow of data from a cable system headend to a customer. A return data path via a telephone network, such as a public switched telephone network provided by AT&T and others, (i.e., a “telephone return”) is typically used for an “upstream” data path, which provides a path for flow of data from the customer back to the cable system headend. A cable television system with an upstream connection to a telephone network is typically called a “data-over-cable system with telephone return.”
An exemplary data-over-cable system with a telephone return typically includes customer premise equipment (“CPE”) entities (such as a customer computer or a Voice over Internet. Protocol (“VoIP”) device), a cable modem, a cable modem termination system, a cable television network, a public switched telephone network, a telephone remote access concentrator, and a data network (e.g., the Internet). The cable modem termination system and the telephone remote access concentrator combined are called a telephone return termination systems.
If the customer premises equipment entity comprises a telephone or a device capable of sending and receiving video or voice signals, the cable modem has to be capable of sending and receiving such signals. In such cases the cable modem typically comprises an internal media terminal adapter, which provides a network interface functionality that accepts analog voice inputs or video signal and generates IP packets using the Real Time Transport protocol, for instance.
In a bi-directional cable system, when the cable modem termination system receives data packets from the data network, the cable modem termination system transmits received data packets downstream via the cable television network to a cable modem attached to the customer premises equipment entity. The customer premises equipment entity sends response data packets to the cable modem, which sends the response data packets upstream via the cable network. The cable modem termination system sends the response data packets back to the appropriate host on the data network.
In the case of a telephone return system, when the cable modem termination system receives data packets from the data network, the cable modem termination system transmits the received data packets downstream via the cable television network to a cable modem attached to the customer promises equipment entity. The customer premises equipment entity sends response data packets to the cable modem, which sends response data packets upstream via the public switched telephone network to the telephone remote access concentrator. Next, the telephone remote access concentrator sends the response data packets back to the appropriate host on the data network.
When a cable modem used in the cable system with the telephone return is initialized, a connection is made to both the cable modem termination system via the cable network and to the telephone return termination system via the public switched telephone network. As the cable modem is initialized, the cable modem initializes one or more downstream channels via the cable network. Also upon initialization, the cable modem receives a configuration file (a boot file) from a configuration server via a trivial file-transfer protocol (“TFTP”) exchange.
The configuration file may include a plurality of configuration parameters encoded in a type-length-value format (“TLV”), for instance. The configuration file may comprise a plurality of Class-of-Service (“CoS”) and Quality-of-Service (“QoS”) parameters. The Class of Service parameters include, for example, maximum allowed rates, minimum reserved rate, maximum latency and a plurality of other parameters. The Quality of Service parameters include, for example, parameters defining delays expected to deliver data to a specific destination, the level of protection from unauthorized monitoring or modification of data, expected residual error probability, relative priority associated with data and a plurality of other parameters.
Upon receipt of the configuration file, a cable modem may register with a cable modem termination system. To do that, the cable modem may send to the cable modem termination system a registration request message comprising a copy of the configuration file including a plurality of QoS and CoS parameters.
Typically, thousands of cable modems are connected to each cable modem termination system, and also a plurality of customer premises equipment (“CPE”) entities such as computers, VoIP compliant devices or telephones are connected to each cable modem. However, there are several problems associated with providing access to subscription services for tens of thousands of cable modems and customer premises equipment entities. At an initialization state or re-initialization state of network equipment, many devices compete simultaneously for dynamically provisioned attributes from the serving network devices. These serving network machines include, for example, servers that provide IP addresses, service authentication, boot configuration files and other policy and management services. There are many standard and proprietary legacy systems in use in large IP networks such as data-over-cable networks, Digital Subscriber Line Access Multiplexer (“DSLAM”) service areas, remote access servers (“RAS”) or Wireless Internet, all of which rely on a few robust servers to handle the traffic. In such centralized systems, delays from many simultaneous requests can overload the servers as in catastrophic recovery instances or first time initialization process.
Some existing provisioning systems have redundant DHCP or TFTP servers that enable back-up (active-standby or active-active modes). These systems rely on all servers getting a request and duplicate responses from the request input. Thus, these systems do not reduce the tendency for a system overload unless the back-up servers are over designed as very expensive ultra-reliable and fast machines. However, even then, the amount of capability to handle catastrophic recovery with a minimal downtime to users is small.
There are other existing solutions that rely on a distribution of client application software that controls client processes requesting services from the networks. However, the problem with these solutions is the scalability and interoperability. Most commonly used user operating systems have embedded processes for making the service requests. Trying to replace or override these methods can easily create problems with other applications or problems with the operating system itself. It also creates version problems in that co-resident applications and user operating systems change radically over time.
The major disadvantage of the existing solutions is that the existing systems tend to block the initialization process and do not have enough time or knowledge base to execute significant traffic redirection policies in real time.
Thus, it is desirable to develop a standard, reliable and efficient way to provide load-balancing tools preferably integrated into the existing cable modem infrastructure. Further, it is desirable to develop a method and system for a dynamic redirection of client requests for distribution of the load among many servers while minimizing the subscriber down time.