At 05:35 PM 10/15/98 -0700, Tony Li wrote:
pete@cobra.brass.com (Peter Polasek) writes:
This interface is extremely mission critical to the point that a 99.9% uptime will not be acceptable. I have the following questions:
1) Bell Atlantic assures us that, because of the redundancy, we can expect 100% uptime from the OC-12. I would like feedback as to whether this is a realistic portrayal of the SONET environment.
How many significant digits do you consider acceptable? Even in an ideal APS environment, link failure detection and protection switching does take finite time. You might get 99.999% uptime, but probably not 99.9999999%.
Methinks that you've been subjected to Marketing. ;-)
For total system uptime 90.0% (one nine or less) Desktop systems. 99.0% (two nines) Intermediate business systems 99.9% (three nines) Most business data systems and workgroup servers 99.99% (four nines) High-end business systems and your friendly neighborhood telco 99.999% (five nines) Bank Data Centers and Telco Data Centers, some ISPs 99.9999% (six nines) Only God and Norad live here. 99.99999% (seven nines) Even God doesn't have pockets this deep. There is a matching exponential cost increment with each step. ___________________________________________________ Roeland M.J. Meyer, ISOC (InterNIC RM993) e-mail: <mailto:rmeyer@mhsc.com>rmeyer@mhsc.com Internet phone: hawk.mhsc.com Personal web pages: <http://www.mhsc.com/~rmeyer>www.mhsc.com/~rmeyer Company web-site: <http://www.mhsc.com/>www.mhsc.com/ ___________________________________________ I bet the human brain is a kludge. -- Marvin Minsky