Apparatus and methods for dynamic bandwidth allocation

Abstract

A system capable of dynamically reserving bandwidth and adjusting bandwidth reservations for active sessions of data communication in a data communications device is provided. The system generally separates the operation of bandwidth allocation and adjustment from the operation of data transport through the device, thereby allowing bandwidth reservations and adjustments to be made without disturbing sessions of data communication that are actively being transported through the device. The system can accept requests to allocate or reserve bandwidth in a data communications device using bandwidth reservation protocols such as RSVP. The reservation requests create sender state data that can be used to compute resource allocation data. The resource allocation data can be used to label data storage locations in a data storage mechanism according to the required bandwidth reservations. A data scheduling apparatus, which is ignorant of particular sessions and specific amounts of reserved bandwidth, examines data and deposits data into data storage locations having a label corresponding to a session identification specified in the data, if any. If an unknown or no session identification is specified in the data, the data scheduler deposits data into a data storage location that is unlabeled or that has an unreserved label. Thus session bandwidth is determined by the percentage of labeled data storage locations for the session. Changes in bandwidth reservations are reflected in the separate operation of alterations made in the data storage labeling scheme, and do not affect the data scheduler, or data dequeuing mechanisms, thus allowing data sessions to continue without interruption during bandwidth adjustments.

Description

RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 09 / 317,381, filed May 24, 1999, issued as U.S. Pat. No. ______, the entire teachings of which are incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] A typical data communications network includes many hosts interconnected by various data communication devices. The data communication devices can be routers, bridges, switches, access servers, gateways, hubs, concentrators, proxy servers, repeaters and so forth which exchange data over an interconnection of data links. The data links may be physical connections or may be provided using wireless communication mechanisms. The network allows data to propagate between various applications that execute on the hosts. The hosts are often general purpose computer systems such as personal computers, workstations, minicomputers, mainframes and the like, or the hosts may be dedicated devices such as web-site kiosks, facsimile servers, vide...

AI Technical Summary

Benefits of technology

[0015] One reason that current implementations of RSVP do not allow bandwidth adjustments once a communication session is in progress is not due to limitations of the RSVP protocol. Rather, the design of prior art data communications devices that support RSVP, such as show in FIG. 1, impose the limitations. A customized data classifier 104 and scheduler 106 support RSVP bandwidth reservation requests and enforce the bandwidth allocation requirements in prior art data communications devices that support RSVP. The RSVP daemon 101 periodically updates the customized classifier 104 with filterspec information which allows the classifier 104 to properly examine and classify packets of data with the flow identification associated with the packets. If a packet is associated with a flow of data for which bandwidth has been allocated via RSVP, the customized classifier 104, for example, directs this packet to a queue reserved for this flow. Once queued, the customized scheduler 106 typically uses a weighted fair queuing algorithm to dequeue the data from the various queues according to the bandwidth allocation requirements associated with the various flows of data in relation to each queue as defined by flowspec requirements.

[0018] The present invention avoids the prior art situation of requiring a break in a data communication session in order to re-allocate or adjust bandwidth reserved for a session. The present invention provides a device implementation that can accept bandwidth allocation changes and can dynamically adjust bandwidth during an active session of data communication using a protocol such as RSVP without requiring a pause or break in the transmission of data along the entire path from sender(s) to receiver(s). This can be accomplished since the present invention manages resources, and is not focused on managing time.

[0022] Another embodiment is provided in which the bandwidth reservation processor further includes a resource allocation table accessible by the bandwidth labeler and a resource allocation calculator coupled to access the resource allocation table independently of the bandwidth labeler. The resource allocation calculator receives the bandwidth allocation information indicated in the first bandwidth reservation request and calculates and stores in the resource allocation table a first percentage of total device bandwidth to allocate to the session of data communication based upon the first bandwidth reservation request. Using these mechanisms, the bandwidth reservation processor can continually allow for bandwidth adjustments over time without disturbing the session of data communication for which the bandwidth reservation exist.

[0034] In another embodiment based on the former embodiment, the step of dynamically adjusting the first bandwidth reservation to produce a second bandwidth reservation includes the steps of accepting a second bandwidth reservation request indicating a second amount of bandwidth to reserve for the session of data communication, and labeling, with an identity of the session of data communication, a second percentage of available data storage locations used to store data transported through the data communications device thus establishing the second bandwidth reservation. The second percentage of storage locations labeled is based upon the second amount of bandwidth requested as indicated in the second bandwidth reservation request, and the second percentage of storage locations labeled is different than the first percentage of storage locations labeled. This allows bandwidth to be adjusted by altering the labeled percentages for storage locations (e.g. in the single rotating queuing structure) associated with (i.e., labeled to receive) various sessions of data communication.

Problems solved by technology

However, one problem that stems from these prior art implementations is that they do not allow adjustments to be made to the amount of bandwidth reserved to a session of data communication without requiring the session to be interrupted.

That is, once the prior art implementations of bandwidth reservation techniques (i.e. modified classifiers and schedulers) reserve a set amount of bandwidth between two or more hosts, the prior art implementations cannot adjust the amount of reserved bandwidth without clearing the session from end-to-end of all data in the path(s) between sending and receiving hosts.

Rather, the design of prior art data communications devices that support RSVP, such as show in FIG. 1, impose the limitations.

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