Method for accelerating TCP flows in communication networks with dynamic control

#The present invention relates to a scheme for reducing fetch time in a communication network, in part based on recognizing the presence or absence of congestion in the network.

#Many communication networks, such as the Internet, rely on packet switching technologies (e.g., X.25, frame relay, asynchronous transfer mode, etc.) to transport variable or uniform blocks (usually termed packets or cells) of data between nodes. The term packet will be used herein to collectively refer to any such block of information. Such networks generally perform two major functions: routing and congestion control. The object of routing is to deliver, correctly and sometimes in sequence, the packets from a source to a destination. The object of congestion control is to maintain the number of packets within the network (or a region or sub-network thereof) below a level at which queuing delays become excessive. Due to finite resources, packets may be dropped rather than queued.

#In essence, a packet switched network is a network of queues communicatively coupled together by communication links (which may be made up of various physical media). At each network node (e.g., a switch or router), there exist one or more queues of packets for each outgoing link. If the rate at which packets arrive and queue up exceeds the rate at which packets are transmitted, queue size grows without bound and the delay experienced by a packet tends towards infinity. In such situations, fetch time (i.e., the time required to download requested content) is increased.

#The present invention is illustrated by way of example, and not limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements and in which:

#FIG. 1 shows an example of a packet switched network having one or more content sources.

#FIG. 2 shows an example of the application of the rate limiting techniques, which are an embodiment of the present invention, to the network shown in FIG. 1.

#A scheme for improving fetch time in a computer or communication network, such as the Internet or other packet switched network, is disclosed herein. Although discussed with reference to certain illustrated embodiments, upon review of this specification, those of ordinary skill in the art will recognize that the present scheme may find application in a variety of systems. Therefore, in the following description the illustrated embodiments should be regarded as exemplary only and should not be deemed to be limiting in scope. It should also be noted that as used herein the term “packet” is meant to broadly refer to packets, cells and other forms of information units used to transport data and/or control information within communications infrastructures (e.g., computer networks, telecommunications networks, data communication networks and the like, for example, the Internet) wherein resources are shared among multiple users and multiple information or traffic streams.

#Existing congestion control approaches have generally viewed network traffic (e.g., the generation of new packets to be injected into a network) as essentially random processes. However, recent work in the area of traffic modeling has shown that network traffic is in fact chaotic in nature. None of the currently proposed congestion control methodologies capture or exploit this characteristic.

#In contrast to these approaches of the past, in the above-cited co-pending patent application, application Ser. No. 09/539,434, which is hereby incorporated by reference in its entirety, the applicants introduced a new approach to congestion control that did exploit the chaotic nature of network traffic. Under the scheme described in the co-pending patent application, the end-to-end packet losses of one or more traffic streams transmitted across a congested network may be reduced by modulating the bandwidths (i.e., the inter-packet delay) of the corresponding traffic streams applied to the node(s) of the network from one or more control points along the network topology. This reduction in packet loss results in a reduction in fluctuations or variability of the controlled traffic streams, an increase in bandwidth utilization of a congested link at downstream points and a reduction in times to transmit files (e.g., to an end-user). The control points can be either upstream or downstream of one or more congestion points along the network.