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       ATM Forum Document Number: ATM Forum/95-467

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       Title: Simulation Results for ERICA Switch Algorithm
       with VBR+ABR traffic

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       Abstract:
       This contribution discusses the issues raised by the presence of VBR
       and presents simulation results for the ERICA switch algorithm.

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       Source:

       Raj Jain, Shiv Kalyanaraman, and Rohit Goyal
       The Ohio State University
       Department of CIS
       Columbus, OH 43210-1277
       Phone: 614-292-3989, Fax: 614-292-2911, Email: Jain@ACM.Org

       The presentation of this contribution at the ATM Forum is sponsored by
       NIST.

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       Date: April 9-14, 1995

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       Distribution: ATM Forum Technical Working Group Members
       (Traffic Management)

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       Notice: This contribution has been prepared to assist the ATM
       Forum. It is offered to the Forum as a basis for discussion and
       is not a binding proposal on the part of any of the contributing
       organizations. The statements are subject to change in form and
       content after further study. Specifically, the contributors
       reserve the right to add to, amend or modify the statements
       contained herein.

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       EFFECT OF VBR:

       Most network links are shared by ABR and VBR traffic with VBR
       traffic taking higher priority. However, most simulation results
       presented so far assume only ABR traffic.  This contribution
       discusses the issues raised by the presence of VBR and presents
       simulation results for the Explicit Rate Indication for
       Congestion Avoidance (ERICA) switch algorithm [1].

       Presence of VBR traffic introduces uncertainty about the
       available link capacity for ABR. The capacity available for ABR
       changes continuously and must be estimated continuously. Unless
       the switch algorithm provides a quick response to these changes,
       the link may be underloaded or overloaded for a long time
       resulting in low throughput or high delay.

       We modified the ERICA algorithm to include an estimation
       algorithm for the available capacity and simulated it with the
       presence of VBR traffic.  The VBR traffic consists of a simple
       square wave which is on for x ms and off for x ms for various
       (small) values of x. The cycle is repeated continuously.  The
       simulation results show that ERICA responds very fast to these
       changes.

       Simulation results will be presented for several configurations
       in both LAN and WAN cases.

       REFERENCES:

       [1] R. Jain, S. Kalyanraman, R. Viswanathan, and R. Goyal, "A
       Sample Switch Algorithm," AF-TM 95-0178R1, February 1995.