[ih] Exterior Gateway Protocol

Wed Sep 2 09:59:06 PDT 2020

EGP preceded NSFnet by about 5 years (RFC 827 was released in October
1982).  CSNET was nascent and IP service on CSNET was still a year or so in
the future.

Could Bob have been thinking about splitting off DoD IP networks to another
provider (e.g. the logical step after inserting the mailbridges) and using
EGP for that purpose?

Craig

On Wed, Sep 2, 2020 at 10:39 AM Jack Haverty via Internet-history <
internet-history at elists.isoc.org> wrote:

> Hi Dan,
>
> Re: the creation of EGP:   Five or ten years ago, I summarized the
> events around the creation of EGP on this list (actually the list when
> it was hosted at ISI).  You may be able to find it in old
> internet-history message archives.
>
> Here's what I wrote. The "Bob" is Bob Kahn, who was one of the ARPA
> Program Managers at the time.  These events occurred just prior to RFC
> 827, sometime in 1981/2:
>
> > I was at one of innumerable meetings.  Sorry, I can't remember where
> or when.
> > It was probably in DC, where I spent a lot of time, but my gut feeling
> tells me
> > it was the European Internet meeting, maybe in Munich.  Anyway,... Bob
> and I
> > were hanging on the same subway strap, with the usual group of a dozen
> or two
> > people heading out to find dinner.  Bob wanted to talk about the Internet
> > architecture, and in particular the core gateways.  He managed over the
> > squealing of the car's wheels to overcome my skepticism and make it
> clear that
> > it would be a good idea to figure out how to make it possible for
> gateways not
> > built by BBN to be full participants in the system of gateways.  I
> don't know
> > whether this was motivated by political pressures to enable
> CSNET/NSFNET, or
> > some technical considerations, or by the ARPA charter to focus on new
> technology
> > and new ideas, rather than replicating the old ones.  But he convinced
> me, and I
> > went away with a new direction, and a harder task to make something
> work using
> > an unproven approach.
> >
> > Back at BBN, the challenge was not only to figure out how to make a
> stable
> > heterogeneous Internet, but also how to convince the people on the
> project that
> > it was a good idea to let other people build gateways and hook them up
> to "our"
> > system.   Fortunately the meetings of the TCP and IP working groups
> were great
> > training for this kind of work.   I recruited one of the best thinkers
> from the
> > ARPANet crowd - Dr. Eric Rosen.  He and I sat down for several multi-hour
> > brainstorming sessions, and came up with the notion of "autonomous
> systems",
> > which were sets of routers owned/managed by a single organization, and
> > interconnected with other such systems to form the overall Internet.
> EGP (which
> > I think evolved into BGP) and the concept of IGP (which basically
> means whatever
> > mechanisms are used among the routers inside their own closed system)
> made it
> > possible to use different approaches within different ASes.   This led
> to RFC
> > 827 and a bunch of others in the early 80s.
> >
>
> IMHO, it's important to note that we defined EGP *not* as a general
> purpose routing protocol, but rather as a "firewall" mechanism, which
> would permit different internal mechanisms (IGPs) to be introduced into
> the Internet, each isolated in its own "autonomous system".   This is
> described in RFC 827.   If a particular AS wanted to protect itself, it
> could design its own IGP to be "skeptical" of routing information it
> received from other ASes through the EGP interactions.   EGP was not
> intended to "solve the problem".  It's purpose was to create an
> experimental testbed in which various ideas could be tried to find good
> answers.
>
> So, the purpose of EGP was to make it possible for diverse groups to try
> out their ideas in the operational Internet, in their own AS, and
> retaining the possibility of isolation between different ASes so that
> flaws in one could be prevented from causing outages elsewhere.   That
> of course depended on exactly what mechanisms each group implemented in
> their own internal IGP mechanisms to provide such isolation.   For
> example, an AS might choose to ignore routing information from another
> AS claiming a "better" route to some network that the AS itself has a
> route to reach totally within that AS.
>
> In particular, Eric continued that work and wrote a series of internal
> BBN documents about ideas for the IGP to be used in the "core gateways"
> AS, which BBN was tasked to operate as a reliable 24x7 core Internet
> service.
>
> I don't know if that BBN IGP ever got implemented in the core
> gateways.   Other groups doing gateways (Dave Mills' et al, the MIT
> group, Cisco, etc.) presumably did their own IGPs, but I never heard
> much about anyone's IGP design or implementation.
>
> /Jack Haverty
>
>
> On 9/2/20 6:55 AM, Dan York via Internet-history wrote:
> > Grant,
> >
> > On Sep 1, 2020, at 11:24 PM, Grant Taylor via Internet-history <
> internet-history at elists.isoc.org<mailto:internet-history at elists.isoc.org>>
> wrote:
> >
> > Does anyone know of any surviving implementations of Exterior Gateway
> Protocol, BGP's predecessor.
> >
> > I know that NetWare 4.x has an implementation of EGP.  But I'm not aware
> of anything else that did support it.  I assume that Cisco IOS of the time
> did.  Did any other network operating system vendor or 3rd party vendor
> have EGP implementations?
> >
> > I have no knowledge of EGP implementations … but related to EGP, one of
> my personal late night hobbies/distractions during the pandemic has been
> diving more deeply into Wikipedia editing, and I noticed that the page for
> EGP needs some citations / references:
> >
> > https://en.wikipedia.org/wiki/Exterior_Gateway_Protocol
> >
> > It also needs more explanation that EGP was replaced by BGP. (The
> current sentence there says “essentially replaced” and is a bit vague with
> no references.)
> >
> > If any of you all here know of any RFCs that explicitly indicate EGP was
> replaced/obsoleted, or if you know of any journal articles, academic
> papers, historical documents, etc., that could be useful, I would be glad
> to update the article a bit. Or if you can point me to any info about the
> creation of EGP (there’s a line that needs a source). Or any other info you
> think would be useful in this Wikipedia article, that would be great.
> >
> > (Note that for info to appear in the English version of Wikipedia, it
> needs to be backed up by a “reliable source” -
> https://en.wikipedia.org/wiki/Wikipedia:Reliable_sources - which includes
> journal articles, academic papers, news articles, RFCs, etc.)
> >
> > Dan
> >
> > P.S. Please do note that this Wikipedia updating is something I do on my
> own personal time and is not part of any of my responsibilities and work at
> the Internet Society. This is just me wanting to update info in Wikipedia
> to be more accurate. :-)
> >
>
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>

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