[ih] The story of BGP?

[Jack Haverty]

Hi Justine,

I wrote up some historical recollections a few years ago - see
http://mailman.postel.org/pipermail/internet-history/2010-February/001219.html
and search in that rather long message for "subway strap" for the
anecdote about the genesis of BGP.

As I recall, we set up the basic architecture for a multi-system
Internet and invented the concept of "Autonomous Systems" (ASes).
>From that, we defined the initial EGP, documented in RFC 827, as the
simplest possible scheme to achieve just the most basic connectivity.
 To paraphrase Einstein - "as simple as possible, but not simpler".

That first EGP was intended more as a "firewall" mechanism than
anything else.  It would enable one AS, such as the "core gateways" to
be operated and managed by one group (e.g., us at BBN), to hopefully
be unaffected by whatever might go on in some other AS.   Extra-AS
information would simply be viewed as suspect, and intra-AS
information would dominate all routing decisions.

We explicitly (probably with ARPA encouragement) left further
evolution of EGP to Someone Else.  If BBN had continued to define and
evolve EGP it wouldn't have been a very good test of whether or not
the architecture really allowed pieces of the Internet to be
developed, managed, and evolved independently.   That vacuum probably
led to the engineers-and-napkins scenario somewhat later, and the
definition of BGP as a replacement for the intentionally rudimentary
EGP.

>From the perspective of the "core" system, EGP made the "core
gateways" a lot less vulnerable to whatever Dave Mills, Noel Chappa,
Jim Mathis, and others did to their own Autonomous Systems....!
They'd try something new, and we'd then get the complaints that the
Internet was broken.   This is a good example of the somewhat mundane
but crucial mechanisms we had to put into the Internet to enable a
single Internet to simultaneously support research and experimental
work as well as reliable infrastructure-class communications.

Bob Hinden may remember more about that era, since as I recall he (I
think with Alan Sheltzer and Mike Brescia) was the one who had to make
it actually work.

/Jack Haverty

On Thu, Feb 7, 2013 at 10:23 AM, Justine Sherry
<justine at eecs.berkeley.edu> wrote:
> Hi Folks,
>
> I was in the graduate networking class yesterday at Berkeley and we
> were discussing the origin of BGP for Interdomain routing, and we
> realized we were all a bit vague on the history of BGP and how it
> developed.
>
> Our (graduate students') understanding goes something like this:
> Pre-1994: EGP, hierarchical Internet to NSFNet
> Some point in 1994: "Flag Day" and everyone switches to BGP
> Since 1994: Minimal evolution in BGP
>
> There are two big gaps here, of course.
> (1) Where did BGP come from, who drafted the spec, why was it settled
> on as what we all switched to in 1994? Were there alternatives in
> mind?
> (2) How is the BGP we switched to in 1994 different from the BGP we
> used today, and who drove those changes?
>
> Does anyone have any pointers to a summary of this history or
> interesting experiences to share? Thank you!
>
> Cheers,
> Justine (& assorted networking graduate students)