Method and apparatus for controlling network bandwidth

Details Method and apparatus for controlling network bandwidth Method and apparatus for controlling network bandwidth

2001-09-19

2004-11-09

Hsu, Alpus H. (Department: 2665)

Multiplex communications

Data flow congestion prevention or control

Flow control of data transmission through a network

C370S392000, C370S471000

Reexamination Certificate

active

06816459

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the field of network technology. Specifically, the present invention relates to a method and apparatus for controlling network bandwidth.
DESCRIPTION OF RELATED ART
With the growth of the Internet, greater demands are being placed on networks, thus causing delays and bottlenecks that may have a severe impact on a user's quality of service.
FIG. 1
illustrates an example of network congestion that may occur on a network today. The network includes multiple nodes, i.e. logical entities that are capable of receiving and transmitting data elements. In this example, data sources and users are nodes on the network. As illustrate, hub
100
is coupled to a network via a T
1
line. A variety of data sources are also shown coupled to the network. The network may be any type of network including a Local Area Network (LAN), a Wide Area Network (WAN) or the Internet. Hub
100
may include any device on the network capable of coupling to data sources. An example of hub
100
may be a repeater or a switch in a corporation that connects all traffic between the users in the corporation and the Internet.
As illustrated, the hub is coupled to numerous users (User
1
through UserN) accessing data sources
150
(
1
)-
150
(N) via the T
1
connection. Communication that occurs only amongst Users
1
-N is not affected by the T
1
connection because the communication may occur without any of the users having to access any of the data sources via the T
1
connection. An example of this type of communication is intranet communications that occur within a corporation, for example. The connection bandwidth of an intranet is generally on the order of 10-100 Mb/sec. This extremely high bandwidth is generally sufficient to handle a large amount of traffic amongst Users
1
-N without causing network congestion.
The problem of network congestion frequently arises when Users
1
-N attempt to perform activities that require a connection and interaction with data sources
150
(
1
)-
150
(N). A T
1
connection, in contrast with the intranet example described above, generally provides a bandwidth of approximately 1.5 Mb/sec. This bandwidth is clearly at least an order of magnitude less than the bandwidth available to intranet users. Thus, if User
1
, for example, attempts to perform transactions with data source
150
(
1
) while UserN simultaneously attempts to perform transactions with data source
150
(N), both users share this T
1
connection to the network. All other users attempting to connect to data sources
150
(
1
)-
150
(N) also share this limited T
1
connection bandwidth. There is currently no restriction on the amount of bandwidth available to each user, and as such, one user may effectively monopolize the entire bandwidth of the T
1
connection.
Thus, depending on the network activity patterns of each of these users, at any given time, the T
1
connection between data source
100
and destination
150
may either be overloaded or underutilized. The T
1
connection in this illustration is therefore a “bottleneck” that may cause severe traffic congestion if all users attempt to perform activities across the network via the T
1
line. The problems caused by this scenario vary in degree based on the type of network and the type of protocol being utilized.
In a Transaction Control Protocol (TCP) network, for example, conventional TCP uses an indirect feedback mechanism to infer network congestion. TCP increases a connections' transmissions rate until it senses a problem such as packet loss, and then it retransmits the prior transmission after backing off for a period of time, resulting in a reduced transmission rate for the connection. TCP uses a sliding window flow control mechanism to increase and decrease the throughput over a network. The sliding window flow control mechanism functions as follows: a sender sends out multiple packets or elements of data, and then waits for an acknowledgment before sending out more data. The receiver acknowledges that it received the data from the sender. The receiver also advertises to the sender how much additional data it can receive. The latter information is known as the receiver's “window size.” The window size thus may change from one transmission of data elements to another.
The mechanism described above for TCP clearly handles network congestion problems in only a limited manner, namely by continuously changing the data flow between a sender and a receiver. This mechanism does not, however, handle the allocation of bandwidth amongst various nodes on a network. Thus, in the example of
FIG. 1
described above, there is no well-defined means today for controlling the bandwidth available to each of the users coupled to hub
100
.
SUMMARY OF THE INVENTION
The present invention discloses a method and apparatus for controlling network bandwidth between a first node and a second node on a network. A data element from the first node to the second node is intercepted. The data element comprises a data portion and a header portion including an original window size. The original window size in the header portion of the data element is replaced with a replacement window size, the data portion of the data element remaining unmodified. The data element is then routed to the second node, the header portion of the data element being coupled to the replacement window size.
Other objects, features and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description.


REFERENCES:
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patent: 4769815 (1988-09-01), Hinch et al.
patent: 5014265 (1991-05-01), Hahne et al.
patent: 5063562 (1991-11-01), Barzilai et al.
patent: 5163046 (1992-11-01), Hahne et al.
patent: 5197127 (1993-03-01), Waclawsky et al.
patent: 5638360 (1997-06-01), Sugawara

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