A novel congestion control strategy in ATM networks

• Published in: Computers & industrial engineering Vol. 25; no. 1; pp. 549 - 552
• Main Authors: Bemmel, Vincent, Ilyas, Mohammad
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Seoul Elsevier Ltd 01.09.1993; Oxford Pergamon Press; New York, NY Pergamon Press Inc
• Subjects: Applied sciences; Asynchronous transfer mode; Broadband; Control systems; Exact sciences and technology; ISDN; Mathematical models; Quality of service; Studies; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Teletraffic; Teletraffic; Traffic congestion; Integrated services digital network; Telecommunication network; Asynchronous transmission
• ISSN: 0360-8352; 1879-0550
• DOI: 10.1016/0360-8352(93)90341-T

In order to guarantee a committed Quality of Service (QoS) to the users of a Broadband Integrated Services Digital Network (B-ISDN), preventive congestion control becomes critical, and is implemented through Call Acceptance Control (CAC), Usage Parameter Control (UPC), and Space Priority functions. Currently, Asynchronous Transfer Mode (ATM) cells are equipped with a 1-bit Cell Loss Priority (CLP) field, which can be used for service-oriented and/or UPC marking. This creates a conflict, since these two marking approaches may have contradicting objectives, and are designed to operate independently. Moreover, by admitting excessive cells as marked traffic, this group is allowed to grow uncontrollably, thereby jeopardizing the QoS committed to other (low priority) marked cells. This paper presents a solution to these problems based on a new 4-class priority strategy that unifies the two marking approaches, by utilizing a 2-bit CLP field. This is implemented by expanding the CLP field with the adjacent 1-bit RES field in the ATM cell header. A new variant of the “marking Leaky Bucket” UPC mechanism, called the Forgiving Leaky Bucket (FLB) will then be positioned at the Network-Node-Interface (NNI) of interworking ATM-based Broadband ISDN subnetworks. The FLB additionally has the power of un-marking ( forgiving) previously marked ATM cells, whenever the network conditions are appropriate. As a result, the end-to-end survival probability of a cell is improved significantly. Furthermore, “forgiving” corrects access-point bias, a phenomenon observed in interworked ATM subnetworks of different congestion conditions. Through simulations it is shown that this new priority strategy provides a significant improvement over the traditional marking Leaky Bucket UPC mechanism.