North American Network Operators Group|
Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical
99 and 44/100 % pure... [Re: outages, quality monitoring, trouble tickets, etc]
At 3:03 PM 11/27/95, Jon Zeeff wrote: >Being in the web hosting business, we measure our own "availability" >and that of others. The top providers do 99.9%.... I recall having calculated several years back that ~4 hours of unavailability (to customers) per 30-day month implies 99.44% availability, an Ivory tower number to be sure (are there any of you out there old enough to remember the incessant ad's for Ivory Soap "99 and 44/100 percent pure"?). Sprint proposed such a number to NSF back in 1989 for the international services under the International Connections Management (ICM) agreement. One thing we both learned along the way was that there are factors beyond any carrier's abiolity to control, especially in international (read "multi-player") services. So, for example, when a cisco box needed re-powering in Stockholm or London, but the local staff was gone for the night and nothing would happen until morning, or when the physical circuit passed through Amsterdam or Germany, and a line break depended on PTT Netherlands or Deutsche Telekom to repair, could/should we hold Sprint responsible? We decided to ask Sprint to produce numbers that related to the portion of the end-to-end linnk under their direct control, e.g., ICM box in Washington to ICM box at London demarc. The numbers, of course, looked a lot better. (I cannot recall them anymore.) But even then, we did not impose quality measures like packet drop rates (and, if we had, how could we know if they were caused by traffic congestion or by poor line quality if the link was heavily loaded almost all day?). Just to mudy the waters a bot more... --SG ____________________________________________ Steve Goldstein, National Science Foundation +1(703)306-1949 Ext. 1119 "Let's not procrastinate until tomorrow!"