Broadband initiatives - impact to your network?

Date: Mon, 28 Jun 2010 16:46:37 -0700
From: "George Bonser" <>

> From: Jonathan Feldman
> Sent: Monday, June 28, 2010 4:14 PM
> To: Randy Bush
> Cc:
> Subject: Re: Broadband initiatives - impact to your network?
> I've never claimed to be particularly bright, but I do like to
> challenge assumptions.

It isn't only the amount of bandwidth available but also in many cases
the protocols used to transmit the data. It takes smarter than the
average bear to figure out how to get data across a fat pipe over a long
distance at a high rate. TCP protocols are limited by the number of
packets allowed to be "in flight" according to how the stack is
configured. One might need to go to unorthodox or rather new methods to
use all the available bandwidth.

There are many cases of someone being stymied as to why they can't even
get anywhere near 10 megabits of throughput on a GigE path from Los
Angeles to London using FTP, for example. In many cases the
responsibility of getting data from point A to point B is handled by
people who don't bring their network operators into the discussion where
problems like this can be pointed out to them. Often the first time the
enterprise network group hears about it is when someone complains that
the "fast pipe" to $continent is "slow" and therefore must be broken and
that is generally followed by the demand that it be fixed immediately if
that demand is not included in the first email.

That is when conversations bearing sounds like mpscp and uftp begin and
then someone says "aw, screw it, just send them a disk".

If you really want to improve on the performance of data transfers over
long distances (e.g. across an ocean), take a look at The Department of Energy and ESnet provides
this information primarily for researchers needing to over large volumes
of data over many thousands of kilometers.

While some of the information will be beyond the capabilities of the
average network user and either end can cause the performance problems,
the information can explain a bit about why the problems exists and does
provide some simple changes that can greatly enhance transfer speed.