End-to-End Traffic Management Issues in IP/ATM Internetworks
draft-jagan-e2e-traf-mgmt-00

Abstract

This document addresses the end-to-end traffic management issues in IP/ATM internetworks. In the internetwork environment, the ATM control mechanisms (e.g., Available Bit Rate (ABR) and UBR with Early Packet Discard (EPD)) are applicable to the ATM subnetwork, while the TCP flow control extends from end to end. We investigated the end to end performance in terms of TCP throughput and file transfer delay in cases using ABR and UBR in the ATM subnetwork. In this document, we also discuss the issue of trade-off between the buffer requirements at the ATM edge device (e.g., Ethernet-ATM switch, ATM router interface) versus ATM switches inside the ATM network. Our simulation results show that in certain scenarios (e.g., with limited edge device buffer memory) UBR with EPD may perform comparably to ABR or even outperform ABR. We show that it is not sufficient to have a lossless ATM subnetwork from the end-to-end performance point of view. The results illustrate the necessity for an edge device congestion handling mechanism that can couple the ABR and TCP feedback control loops. We present an algorithm that makes use of the ABR feedback information and edge device congestion state to make packet dropping decisions at the edge of the ATM network. Using the algorithm at the edge device, the end-to-end performance in throughput and delay are improved while using ABR as the ATM subnetwork technology and with small buffers in the edge device.

Authors

Dr. Nanying Yin
Dr. Shantigram Jagannath

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