RE: Networking Pearl Harbor in the Making

[Robert Bonomi <bonomi () mail r-bonomi com>]

> Subject: RE: Networking Pearl Harbor in the Making
> Date: Mon, 7 Nov 2005 11:11:52 -0500
> From: "Hannigan, Martin" <hannigan () verisign com>
>
>
> > On Monday 07 Nov 2005 3:42 pm, Hannigan, Martin wrote:
> > > It's an argument for vendor diversity.
> >
> > No it is an argument for code base diversity (or better 
> > software engineering).
> >
> > Vendor diversity doesn't necessarily give you this, and you 
> > can get this with 
> > one vendor.
>
> How so? Haven't we recently seen an across the board bug in
> multiple version of $vendor code?

Excerpt from "Logic 101 -- Introductory Logical Reasoning":

   "Can" does not mean the same thing as "will". 

And, thus, the fact that one vendor has an across-the-board bug does _not_ 
mean that the same situation exists at =all= vendors..

The bug in multiple versions ov $vendor's code was directly attributable to
those 'multiple versions'  all being derived (at different points in time,
and/or for different deployment niches) from the same primary 'code base'.
Note: "code base", *singular*.  The problem existed in the core code, so,
naturally, it was present in all the varients of that *single* core.
> > Vendor diversity might be a good idea, but for other reasons.
>
> Sure. There are more reasons than one to do it. I was specifically
> pointing out that code diversity is a good one - and not forgetting
> associated cost and economic impacts as mentioned in a later followup.

Vendor diversity does *not* _guarantee_ diversity in code-base.

You have to *explicitly* spec/check/test for code-base diversity, to ensure
that you have code-base diversity.

It is _possible_ to get code-base diversity with multiple purchases from a
 single manufacturer/vendor.
It is _possible_ to have a single common code-base among purchases from
  disparate manufacturers/vendors.

The "probability" of getting things with different code-bases -- *without*
*actually*checking*for*it* -- is higher if you purchase from multiple
manufacturers/vendors, rather than from a single one.

"Higher probability" != "guaranteed"   Hence the need to explicitly check,
if said diversity is a requirement.