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From: NIC at SRI-NIC
Subject: DDN Newsletter No. 26
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======================================================================
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
<DDN-NEWS> 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] <NETINFO>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.
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