Re: SONET ring questions

["Roeland M.J. Meyer" <rmeyer () mhsc com>]

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.
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