Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site watmath.UUCP Path: utzoo!watmath!mwang From: mwang@watmath.UUCP (mwang) Newsgroups: ont.events Subject: UW Systems Seminar, Dr. Molle on "Virtual Time CSMA: Why Two Clocks are Better Than One" Message-ID: <6971@watmath.UUCP> Date: Tue, 21-Feb-84 14:10:45 EST Article-I.D.: watmath.6971 Posted: Tue Feb 21 14:10:45 1984 Date-Received: Wed, 22-Feb-84 02:06:45 EST Expires: Sat, 3-Mar-84 00:00:00 EST Organization: U of Waterloo, Ontario Lines: 36 _D_E_P_A_R_T_M_E_N_T _O_F _C_O_M_P_U_T_E_R _S_C_I_E_N_C_E _U_N_I_V_E_R_S_I_T_Y _O_F _W_A_T_E_R_L_O_O _S_E_M_I_N_A_R _A_C_T_I_V_I_T_I_E_S _S_Y_S_T_E_M_S _S_E_M_I_N_A_R - Friday, March 2, 1984. Dr. M. Molle of the University of Toronto will speak on ``Virtual Time CSMA: Why Two Clocks are Better than One.'' TIME: 2:30 PM (Please Note) ROOM: MC 5158 ABSTRACT Carrier sense multiple access (CSMA) algorithms are distributed algorithms used in local area networks to serialize the transmission of messages over a shared broadcast communications channel. A new CSMA algorithm called virtual time CSMA is described and analyzed. Unlike other CSMA algorithms, the operation of virtual time CSMA reduces to the ideal case in the zero propa- gation time limit: a work-conserving, first-come first-served M/G/1 queueing system. This observation suggests a technique for constructing simple closed- form bounds for the mean message delay. This technique is of independent interest because of its applicability to certain `sliding window' tree algorithms. Comparis- ons between simulation and analysis show remarkably good agreement. February 21, 1984