bad press for NSFNET
Thu, 21 Apr 88 11:00:30 EDT

In response to Kent England:
?> If there is nothing in print, I would like to invite someone
?> from MERIT or other knowledgable developer to post something about how
?> these RTs work compared to some plain vanilla (:-) router like a
> cisco, a proteon, a fuzzball, or homegrown router.
The routing algorithm internal to the backbone is an implementation of
the ANSI IS-IS Intradomain routing proposal. In a nutshell, it is an
SPF variant with stable link metrics (assigned by "system management,"
which could be human or electronic). Reachability of routers and
networks are flooded throughout the backbone.

EGP is used to pass reachability info between the backbone, the
regionals, and the ARPAnet. Various filtering tricks are used to
try to ensure that ARPA routes don't leak out into the regionals,
for example. Tables of potential EGP announcements are used to
ensure that bogus info is not imported from the regionals.

The routing algorithm is documented in ANSI X3S3.3/87-150R, which
we will be making available for anonymous FTP once the NSFnet
Info Services machine is in production. Local adaptations of
the algorithm to DOD IP and the EGP mechanisms will likely be
published in a paper once the panic subsides a little.

Dave Katz, Merit/NSFnet

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