Routing between the NSFNET and the DDN (RFC1133)

Network Working Group J. Yu Request for Comments: 1133 H-W. Braun Merit Computer Network November 1989

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 NSFNET.

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

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RFC 1133 Routing between the NSFNET and the DDN November 1989

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 under separate administrative control, typically by a NSFNET mid- level network.

For a period of time, the traffic between the NSFNET and the DDN was carried by three ARPANET gateways. These ARPANET gateways were under the administrative control of a NSFNET mid-level network or local site and had direct connections to both a NSFNET NSS and an ARPANET PSN. These routers had simultaneous EGP sessions with a NSFNET NSS as well as a DDN Mailbridge. This resulted in making them function as packet switches between the two peer networks. As...