DESIGN CONSIDERATIONS FOR THE VIRTUAL SOURCE VIRTUAL DESTINATION (VS/VD) FEATURE IN THE ABR SERVICE OF ATM NETWORKS/

The Available Bit Rate (ABR) service in ATM networks uses end-to-end r ate-based flow control to allow fair and efficient support of data app lications over ATM networks. One of the architectural features in the ABR specification [ATM Forum, ATM Traffic Management Specification Ver sion 4.0, April 1996] is the Virtual Source/Virtual Destination (VS/VD ) option. This option allows a switch to divide an end-to-end ABR conn ection into separately controlled ABR segments by acting like a (virtu al) destination on one segment, and like a (virtual) source on the oth er. The translation and propagation of feedback in the VS/VD switch be tween the two ABR control segments (called ''coupling'') is implementa tion specific. In this paper, we model a VS/VD ATM switch and study th e issues in designing the coupling between ABR segments. We identify a number of implementation options for the coupling and show that the c hoice of the implementation option significantly affects the system pe rformance in terms of (a) the system stability in the steady state, (b ) the time to respond to transient changes and converge to the steady state, and (c) the buffer requirements at the switches. (C) 1998 Publi shed by Elsevier Science B.V. All rights reserved.