Routing between the NSFNET and the DDN (RFC1133)
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2000-Sep-12
Internet Society Requests For Comment (RFCs)
J.Y. Yu: AUTHOR [+2]
Status of this Memo
Network Working Group J. Yu
Request for Comments: 1133 H-W. Braun
Merit Computer Network
Routing between the NSFNET and the DDN
Status of this Memo
This document is a case study of the implementation of routing
between the NSFNET and the DDN components (the MILNET and the
ARPANET). We hope that it can be used to expand towards
interconnection of other Administrative Domains. We would welcome
discussion and suggestions about the methods employed for the
interconnections. No standards are specified in this memo.
Distribution of this memo is unlimited.
1. Definitions for this document
The NSFNET is the backbone network of the National Science
Foundation's computer network infrastructure. It interconnects
multiple autonomously administered mid-level networks, which in turn
connect autonomously administered networks of campuses and research
centers. The NSFNET connects to multiple peer networks consisting of
national network infrastructures of other federal agencies. One of
these peer networks is the Defense Data Network (DDN) which, for the
sake of this discussion, should be viewed as the combination of the
DoD's MILNET and ARPANET component networks, both of which are
national in scope.
It should be pointed out that network announcements in one direction
result in traffic the other direction, e.g., a network announcement
via a specific interconnection between the NSFNET to the DDN results
in packet traffic via the same interconnection between the DDN to the
2. NSFNET/DDN routing until mid '89
Until mid-1989, the NSFNET and the DDN were connected via a few
intermediate routers which in turn were connected to the ARPANET.
These routers exchanged network reachability information via the
Exterior Gateway Protocol (EGP) with the NSFNET nodes as well as with
the DDN Mailbridges. In the context of network routing these
Mailbridges can be viewed as route servers, which exchange external
network reachability information via EGP while using a proprietary
protocol to exchange routing information among themselves.
Currently, there are three Mailbridges at east coast locations and
three Mailbridges at west coast locations. Besides functioning as
route servers the Mailbridges also provide for connectivity, i.e,
packet switching, between the ARPANET and the MILNET.
The intermediate systems between the NSFNET and the ARPANET were