nanog mailing list archives

Re: Limits of reliability or is 99.999999999% realistic


From: <mdevney () teamsphere com>
Date: Mon, 27 Nov 2000 12:25:44 -0800 (PST)


All--

In a perfect world, your provider says the service is always on, the
service is always on.  In the real world, we have to deal with outages --
some kids vandalise a phone box, new tech trips over some cables, some
idiot telco misimplements MPLS and brings your service down for a day....

These things happen, and sometimes we all just have to suck it down and
deal with it.  But if it happens continuously, you have to ask your
provider for some assurance that it won't keep happening.  This is what
SLAs are for.

In my experience, a company that delivers reasonable levels of service has
no need for SLAs with their clients.  The service is up, everybody is
happy.  SLAs are like your parent telling you to do the dishes again "and
get it right this time, or else you go to bed with no jell-o!"

Which s why, in looking for a vendor, I ask for an SLA.  If they have one
as a standard offering, then I know that they've messed up a lot in the
past, and will probably be messing up more than I like in the
future.  It's like the kid who never did his homework coming up to the
teacher on the last day of school asking for extra credit.  NO YOU
FOOL!  You should have done it right the last 180 days!

Anyway, just my thoughts.

On Mon, 27 Nov 2000 Toby_Williams () enron net wrote:

Date: Mon, 27 Nov 2000 10:14:43 +0000
From: Toby_Williams () enron net
To: nanog () nanog org
Subject: Limits of reliability or is 99.999999999% realistic






SLAs are the point where commercial & operational worlds collide. The numbers
being offered should:

Reflect the targeted quality of the service
Tie in with meaningful damages for not achieving them

In a market where I can offer 99.7% or 100% and the difference is a whole day's
service credit, I know what I'd be offering. No question.

If on the other hand, the expectation is that I pay out a year's contract value
in cash upfront every time I miss a target in a month, then I'd only want to
offer a target that will *always* be achieved.

In the market at the moment, the situation is much closer to the first scenario
than the second - ie damages for SLAs do not mean anything to either:

the buyer, as compensation for not receiving the service that they have
contracted for;
or
the seller as a motivation to work within the targets, because capped service
credit agreements do not touch the bottom line

Today, in the IP market, it is irrelevant whether services come with 99.0 or
99.99999 SLAs & at some point the market needs to address the responsibility
that if they are to offer a service of a certain "guaranteed" quality, then they
should stand-by that guarantee with their money and give this guarantee meaning.

I don't think this is the case at the moment, and that's why we even see 100%
SLA in the market - because the level of pay-outs on SLAs don't matter to the
seller.

No. I'm not suggesting that sellers offer guarantees for consequential losses.
Simply ones that:

1. give the buyer the peace of mind that if the service they've contracted to is
below par, that they will have enough money put back in their pocket for them to
have replaced their service, like-for-like in the market, to cover themselves
over the period.

2. enable the market players to truly differentiate their service offerings by
quality, rather than marketing.

Toby
[std. disclaimer of responsiblity here]

Date: 25 Nov 2000 20:24:48 -0800
From: Sean Donelan <sean () donelan com>
Subject: Limits of reliability or is 99.999999999% realistic

<snipped for brevity>

But back to my question. ?What is the real requirement? ?Amazon.COM had
system problems on Friday, and their site was unusuable for 30 minutes,
definitely not 99.999%. ?But what did that really mean? ?The FAA loses
its radar for several hours in various parts of the country. ?What did
that really mean? ?Essentially every system given as an example of "high-
availability, high-reliability" I've looked at, doesn't hold up under
close examination.

Is 99.999% just F.U.D. created by consultants?

Instead of pretending we can build systems which will never fail, should
we work on a realistic understanding of what can be delivered?








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