[20534] in North American Network Operators' Group
Re: SONET ring questions
daemon@ATHENA.MIT.EDU (Roeland M.J. Meyer)
Fri Oct 16 06:12:06 1998
Date: Fri, 16 Oct 1998 02:35:40 -0700
To: Tony Li <tli@juniper.net>
From: "Roeland M.J. Meyer" <rmeyer@mhsc.com>
Cc: pete@cobra.brass.com (Peter Polasek), nanog@merit.edu
In-Reply-To: <82k9211gyd.fsf@chimp.juniper.net>
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
