11-May-83 09:08:52-PDT,11762;000000000001 Return-path: Mail-From: SMTP created at 11-May-83 09:06:48 Received: FROM SRI-NIC BY USC-ISIF.ARPA WITH TCP ; 11 May 83 09:06:56 PDT Date: 10 May 1983 1630-PDT From: NIC at SRI-NIC Subject: DDN Newsletter No. 26 To: DDN-NEWS-DIST: ; ====================================================================== DDN-NEWS 26 NETWORK INFO CENTER for 6 May 1983 DCA DDN Program Mgt Office (NIC@SRI-NIC) (415) 859-3695 DEFENSE DATA NETWORK NEWSLETTER (Maximum Distribution Requested. The DDN Newsletter is published by the Network Information Center under DCA contract. For subscription, contact NIC@SRI-NIC. Back issues obtainable by FTP from the directory at SRI-NIC [10.0.0.73].) ====================================================================== Section I. OFFICIAL Topic: - ARPANET/MILNET SPLIT - How It Will Happen Section II. UNOFFICIAL (none this issue) ---------------------------------------------------------------------- ARPANET/MILNET SPLIT - HOW IT WILL HAPPEN. Restructuring the ARPANET into two networks, an experimental network (ARPANET) and an operational network (MILNET), began with the establishment of the MILNET on 4 April 1983. This Newsletter is the first of a series of newsletters which will describe the evolutionary process which will be used to accomplish the split. While it is the intent of the DDN-PMO to minimize any user impact, some effects cannot be avoided. These newsletters are intended to keep users informed so that they can better participate in split activities and plan for any impacts. This introductory article will briefly address major milestones in the split, and describe the two nets after the split. Future newsletters will elaborate on these and related issues. 1. Major Milestones. Four dates stand out above others as significant in the effort to divide the ARPANET: 4 April 1983, 4 October 1983, 1 December 1983 and the first quarter of CY 1984. On 4 April 1983, the MILNET was established and CSIF billing for ARPANET service discontinued for those DoD nodes and TACs designated to become part of the Defense Data Network - Unclassified Segment, the MILNET. With this action, the DDN (MILNET) came officially into existence, and the evolutionary process of partitioning the existing shared backbone into the MILNET and the ARPANET Experimental Network began. A complete list of MILNET and ARPANET facilities may be obtained from the Network Information Center (NIC) from the file [SRI-NIC] MILNET-ARPANET.LIST . On 4 October 1983, the MILNET and ARPANET will become separate networks. This initial partitioning will be implemented by exercising software in each IMP which enforces the segregation of hosts and TACs into separate communities of interest. Electronic mail service between ARPANET and MILNET will be provided for all users, and approved hosts will be authorized additional services, i.e., telnet and FTP, where required, via devices known as mail-bridges. Implementation of this software segregation of the networks, or software split, will require each host to update its tables to reflect correct network numbers. The ARPANET hosts will remain in Net 10, while the MILNET hosts will change to Net 26. Future newsletters will address these, and other issues pertinent to the software split in depth. 1 December 1983 is the target date for Phase One of the TAC Access Control System (TACACS). TACACS will be installed on the MILNET only. Software development for Phase One is nearing completion by BBN, and the major effort remaining is user registration, which will be accomplished during the coming months by SRI International (SRI). This undertaking is being accomplished by expanding the existing WHOIS database to become the official register of authorized network users, with a subset being the register of authorized MILNET TAC users. SRI will be working very closely with Host Administrators at each MILNET site during the registration and beyond. Your cooperation and input to SRI requests for information is officially solicited. TACACS will be the subject of a future Newsletter. The first quarter, CY 1984, has been established as the goal for completion of the circuit reconfiguration necessary to physically divide the two networks. The date for this milestone is somewhat soft since it depends upon successful completion of a large number of circuit orders, many of which involve long lead times. When the date for this milestone is more precisely known, it will be publicized. Because of the software split occurring in October 1983, however, the physical partitioning should be transparent to the user community. 2. Communities of Interest. Three distinct communities of interest have been identified among users presently on the ARPANET; these are the ARPANET Community, the Military Open Community, and the Military Closed Community. Each of these have their own purposes to fulfill and requirements which a network must serve. The term Military, in this context, is not to be understood as exclusively DoD, but as referring to its primary make-up. It may also include contractors and other organizations which support DoD programs, as well as the non-DoD Government agencies. The ARPANET Community consists of hosts and users who participate with DARPA in network and internetwork experimentation. Communications reliability, although important, is secondary to research needs. For example, among network experiments currently projected by DARPA, it is planned to segment the network in order to further explore the use of packet radio techniques for network reconstitution. Although the disruption caused by such experiments is hardly affordable in an operational environment, it is an acceptable price to pay within a community where research is the prime reason for existence. The Military Open Community consists of hosts and users who, to satisfy their assigned mission, require continued access to the ARPANET community, but whose mission is primarily operational rather than experimental in nature. Because of their mission orientation, the users in this community would find the disruptions associated with the experimental environment of the ARPANET community to be unacceptable. A large portion of this community are themselves in the Research and Development business, but do not meet the specific criteria of participating with or in coordination with DARPA in network or internetwork experimentation. The smallest of the three communities using the existing ARPANET consists of military hosts and users who communicate primarily with their own interest group, and have no requirement for continued communication with the ARPANET community. Although currently small, projections of new users who will require service in the coming years indicate this to be a strong growth area. Examples of new users in this group include personnel centers, finance centers, and comparable organizations for whom general access clearly is not advised. 3. Network Architecture. (a) Three Communities on Two Backbones. With the communities of interest clearly identified, the task becomes how to partition the network to meet the needs of all, with least disruption in the process, and at the least cost. The approach chosen is a physically separated, dual-backbone design with both military communities on one backbone, and the ARPANET community on the other. Once separated, the backbones will be connected by mail-bridges (see below) in order to maintain communications between the MILNET Open Community and the ARPANET community. Within the MILNET, the Open and Closed communities will be separated by the continued use of the IMP software used for the initial ARPANET/MILNET split in October. Mail Relays (see below) which will only be capable of passing electronic mail will be the only interconnections provided. A schematic drawing of this topology is shown below. Future newsletters will elaborate on various features of the topology. ---------------------------------------------------------------------- MILNET BACKBONE ARPANET BACKBONE ************************ ************************ * * * * * -------------------- * * -------------------- * * | | * ------------- * | | * * | Milnet Open |------| Four Mail |-------| ARPANET | * * | Community | * | Bridges | * | Community | * * | | * ------------- * | | * * | | * * | | * * | | * ------------- * | | * * | |------| NIC* |-------| | * * | | * ------------- * | | * * -------------------- * * -------------------- * * | * ************************ * | * * -------------- * *The Network Information Center (NIC) * | Mail Relay | * serves both networks. * --------------- * * | * * | * * -------------------- * * | | * * | Milnet Closed | * * | Community | * * | | * * -------------------- * ************************ FIGURE 1. MILNET/ARPANET TOPOLOGY SCHEMATICALLY DISPLAYED. --------------------------------------------------------------------- (2) Equipment and Systems. MAILBRIDGE The mail-bridge connects the MILNET and ARPANET backbones. Bridges are being installed and will be operational prior to the software split in October. The mail-bridge provides electronic mail services for all users between the two nets and, on a controlled basis, full gateway service for MILNET hosts who request it. A future newsletter will describe the procedure for obtaining this service. MAIL-RELAY The Mail Relay is functionally similar to the mail-bridge in that it passes electronic mail; it is dissimilar in that, as presently designed, it is incapable of passing anything else. One or more mail relays will be placed between the Military Open Community and the Military Closed Community to provide mail service. The relay(s) are not expected to be operational prior to the physical split in 1984. ELECTRONIC MAIL SERVICE In order to ease the process of relocating mail accounts, the DDN will provide a limited number of mail accounts. Priority for these accounts will be given to MILNET users whose present accounts are on hosts which have been aligned to the ARPANET, leaving the user without a usable account. Such users should exhaust other means of obtaining mail service before requesting service through the DDN PMO. -------