ATM Networks: An Overview
ATM Networks: Overview q STM = Synchronous Transfer Mode, ATM = Asynchronous Transfer Mode Allows any-speed and even variable rate connection Broadband = Rate greater than primary rate (1.5 Mbps) q ATM = Short fixed size 53-byte cells q Connection oriented Þ Virtual Channels (VC) q Labels vs addresses Þ Better scalability in number of nodes o Slotted system Þ Better scalability in distance-bandwidth o Switches vs routers Þ Cheaper due to fixed size, short address, simplicity o Seamless Þ Same technology for LAN, MAN, WAN o Data, voice, video integration o Everyone else is doing it History of ATM q 1980: Narrowband ISDN adopted q Early 80's: Research on Fast Packets q Mid 80's: B-ISDN Study Group formed q 1986 ATM approach chosen for B-ISDN q June 1989: 48+5 chosen (64+5 vs 32+4). q October 1991: ATM Forum founded q July 1992: UNI V2 released by ATM Forum q 1993: UNI V3 and DXI V1 q 1994: B-ICI V1 Private NNI Private UNI Public UNI ATM Network Interfaces Computer Private S