Industry standard bandwidth guarantee?

Thu Oct 30 19:44:43 UTC 2014

I'm willing to recommend to sales people that they advertise the size of the *usable* tube as well as the tube overall, but I'm fairly sure they won't care.  Ben rightly stated the order of operations: BS quote > disappointment > mea culpa/level setting.

If that fails I'll at least make sure no one quotes circuit sizes in terms of "movies transferred," or whatever metric is popular at the moment.

>From that nice gronkulator page I see a couple of MPLS and a dot1q tag bringing a theoretical limit down to around 94% (non-jumbos), which to my conservatively estimating mind means customers should expect ~90 on a normal day.  This isn't factoring latency, intermittent loss, or congestion elsewhere on the tubes, so I'm not sure where this has gotten me.  A number has been specified to be sure, but one that blows away with a gentle sneeze.

From: rafael at gav.ufsc.br
Date: Thu, 30 Oct 2014 13:21:41 -0500
Subject: Re: Industry standard bandwidth guarantee?
To: mysidia at gmail.com
CC: bensjoberg at gmail.com; ktokash at hotmail.com; nanog at nanog.org

You can't just ignore protocol overhead (or any system's overhead). If an application requires X bits per second of actual payload, then your system should be designed properly and take into account overhead, as well as failure rates, peak utilization hours, etc. This is valid for networking, automobile production, etc etc..
On Thu, Oct 30, 2014 at 7:23 AM, Jimmy Hess <mysidia at gmail.com> wrote:
On Wed, Oct 29, 2014 at 7:04 PM, Ben Sjoberg <bensjoberg at gmail.com> wrote:

> That 3Mb difference is probably just packet overhead + congestion

Yes...  however, that's actually an industry standard of implying

higher performance than reality,  because end users don't care about

the datagram overhead which their applications do not see they just

want X  megabits of  real-world performance, and this industry would

perhaps be better off if we called a link that can deliver at best 17

Megabits of Goodput reliably a  "15 Megabit goodput +5 service"

instead of calling it a "20 Megabit service"

Or at least appended a disclaimer   *"Real-world best case download

performance: approximately  1.8 Megabytes per second"

Subtracting overhead and quoting that instead of raw link speeds.

But that's not the industry standard. I believe the industry standard

is to provide the numerically highest performance number as is

possible through best-case theoretical testing;   let the end user

experience disappointment and explain the misunderstanding later.

End users also more concerned about their individual download rate on

actual file transfers  and not  the total averaged aggregate

throughput of the network of 10 users  or 10 streams downloading data

simultaneously,    or characteristics transport protocols are

concerned about such as fairness.

> control. Goodput on a single TCP flow is always less than link

> bandwidth, regardless of the link.

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-JH