Multiplex communications – Data flow congestion prevention or control – Control of data admission to the network
Reexamination Certificate
1999-05-06
2003-11-25
Hsu, Alpus H. (Department: 2665)
Multiplex communications
Data flow congestion prevention or control
Control of data admission to the network
C370S235000, C370S253000, C370S338000, C370S349000, C455S012100, C709S203000, C709S218000, C709S233000
Reexamination Certificate
active
06654344
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to telecommunication techniques. More particularly, the present invention provides a technique including methods and systems for managing the flow of information in a TCP connection over a satellite system for use in a wide area network of computers such as the Internet. The present invention provides a controlled flow of information with high speed and quality transmission of signals to a distant location over a satellite system using an Xpress Transport Protocol (herein “XTP”) protocol, for example. But it will be recognized that the invention has a much wider range of applicability; it can also be applied to a private bridged network, terrestrial wireless network links, and the like.
The Internet is an international “super-network” connecting together millions of individual computer networks and computers. The Internet is generally not a single entity. It is an extremely diffuse and complex system over which no single entity has complete authority or control. Although the Internet is widely known for one of its ways of presenting information through the World Wide Web (herein “Web”), there are many other services currently available based upon the general Internet protocols and infrastructure.
The Web is generally easy to use for people inexperienced with computers. Information on the Web can be presented on “pages” of graphics and text that contain “links” to other pages either within the same set of data files (i.e., Web site) or within data files located on other computer networks. Users often access information on the Web using a “browser” program such as one made by Netscape Communications Corporation of Mountain View, Calif. or Microsoft Corporation of Redmond, Wash. Browser programs process information from Web sites and display the information using graphics, text, sound, and animation. Accordingly, the Web has become a popular medium for advertising goods and services directly to consumers.
The Internet supports many other forms of communication. For example, the Internet allows one-to-one communication via electronic mail, which is commonly known as “e-mail.” The Internet also has “bulletin boards” which are used by users to post colorful text and graphics for others to read and respond to. For real time communication, the Internet has “chat rooms” and the like, which allow users to communicate to each other by way of typed messages. In some cases, the Internet can also be used for voice communication between users. All of these forms of communication are possible, at least in part, by way of an important connection, which allows information to be transmitted from many different servers on the Internet.
The Internet is based on the TCP/IP protocol suite. At the network layer, an Internet Protocol, which is known as IP, provides a mechanism to deliver packets addressed to individual computers. The Internet has a plurality of computer systems implementing IP, which are generally interconnected to each other using local area networks and dedicated transmission lines, to form a wide area network of computers. IP packets are delivered on a best effort basis and are not guaranteed to arrive at their intended destination, which is known as “unreliable” service.
For many applications that require reliable data delivery service, the Internet uses a connection mechanism called Transmission Control Protocol, which is known as TCP. TCP has a variety of desirable characteristics that allows it to be suitable for communication over the Internet. For example, TCP considers the data size or best sized segment of data to send from a transmitting server over the communication medium to a receiving server. Additionally, TCP maintains a timer, which waits for the receiving server to send an acknowledgment of the reception of the data segment from the transmitting server. If the timer times out before the acknowledgment is received, TCP resends the data segment, which provides reliability in the communication. TCP also maintains a checksum on its header and data, which monitors any modification in the data in transit. If the data arrives with an invalid checksum, TCP discards the data and does not acknowledge receiving the data. If data segments arrive out of order, TCP can also recombine the segments in order at the receiving server. Furthermore, TCP provides flow control, which only allows a finite amount of data to be sent to a buffer on the receiving server. This prevents a fast server computer from overflowing all the buffers on a slower server computer.
Although TCP has been well suited for transmitting Internet data between a plurality of servers, which are coupled to each other by way of conventional telephone systems and lines with similar characteristics, TCP has many limitations. For example, TCP is suitable for “short hops” but often slows down communication over extremely long distances which can have significant latency (e.g., transcontinental hops via satellite). Here, the flow control and acknowledgment features take too long to send and receive, which make communication slow. Additionally, opportunities for gains in efficiency still exist. In particular, TCP has been found to be slow and cumbersome for transmission of Internet data over a satellite network, for example. Additionally, networking using satellites often encounters significant bit error rates, which leads to further slowing of TCP connections. These and other limitations will be more fully described according to the Figs. below.
From the above, it is seen that a more efficient way of managing the transmission of information for Internet services over large geographical regions using a wireless communication media is highly desirable.
SUMMARY OF THE INVENTION
According to the present invention, a technique for controlling information flow in TCP connections over a wireless wide area network is provided. In an exemplary embodiment, the present invention provides methods and systems for controlling the rate that information flows over a TCP connection to an Xpress Transport Protocol (herein “XTP”) connection, for example.
In a specific embodiment, the present invention provides a method for controlling the flow of information over an internet connection established across a satellite link. The method can be operable on a large variety of systems, such as a system comprising one or more clients, one or more servers, a first gateway connected to at least one client, a second gateway connected to at least one server, and a wireless telecommunications link between these gateways. The method includes intercepting a connection attempt with a server initiated by a client. A connection can be established between a first gateway and a second gateway over the telecommunications link, that can be a satellite link or the like. The method can include a step of determining a round trip time for data to travel from the client to the server over the connection. A data rate for the connection can also be determined. From the round trip time and the data rate, a bandwidth delay product can be determined by the method. The method can also determine a flow control limit for the connection from the bandwidth delay product. A step of limiting data transfer over the connection based upon the flow control limit can be part of the method. The combination of such steps as these can provide a method for controlling the flow of TCP data over networks spanning large geographical regions using a wireless communication media, and the like.
In another embodiment, the present invention can select from among connections, ones that can benefit available system resources by being flow controlled. Some embodiments can screen for flow control those connections that are not initializing, or are transferring data in blocks below a threshold value, or above a threshold value and the like. In many embodiments, a bandwidth delay product for the connection can be determined by multiplying round trip time and data rate. In some embodiments, a flow control limit for a connection can be determine
Hartrick Timothy W.
Hasson Marc B.
McCooey Jeremy A.
Toporek Jerome D.
Hsu Alpus H.
Mentat Inc.
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