More on DSN

by Dr. Seuss of the OCPP

Overview of the DSN

Unbeknownst to most phreaks, the AUTOVON proper was taken off-line decades ago.  In this day and age a new system has arisen that embraces the former AUTOVON and all other military voice/data systems: the Defense Switched Network.

The Defense Switched Network (DSN) was the result of a swift kick in the ass to the aging military phone network, replacing analog switches first with 5ESS systems and then with a variety of smaller switches.

The DSN was built by AT&T and originally based on 5ESS switches located all over the world.  The DSN is divided into two parts.  The everyday transmissions are run over the so-called "BLACK DSN" while secure information is transmitted over the secured "RED DSN."

BLACK DSN

The BLACK DSN is an unsecured automatic phone system serving the U.S. military and related government agencies around the world.  The BLACK DSN consists of an unspecified number of Siemens (KNS-4100) and Nortel (SL-100) switches maintained by GTE Government Systems employees.  All BLACK switches are polled by the Regional Control Center for faults on a regular basis by a system called ADIMSS, and all outages and other problems are sent from there directly to the Chief of Operations.

While the DSN itself is considered insecure, the use of STU-III voice encryption telephones is standard procedure.

Like the AUTOVON before, a central feature of the BLACK DSN is the Multi-Level Precedence Preemption (MLPP), a slick military term for priority routing.

As mentioned in the Spring issue, BLACK DSN numbering is handled on an NPA-NXX-XXXX format: The 312 NPA serves CONUS (CONtinental United States) and Canada, the 313 NPA serves the Caribbean, the 314 NPA serves Europe, the 315 and 317 NPAs serve the Pacific and Alaska, and the 318 NPA serves Southwest Asia.

The BLACK DSN has a BBS that can be reached via Telnet at: dsnbbs.ncr.disa.mil or calling 703-735-8178.

The BLACK DSN phone directory can be found at: dsnbbs.ncr.disa.mil/phone97/dsnbct97.txt

RED DSN

RED DSN is a secure automatic phone system serving the U.S. military and related government agencies such as the National Command Authority (NCA), the National Military Command Center (NMCC), the Airborne Command Post, the Commanders-in-Chief, select military depart-ments, and "Allies of the United States" around the world.  Unlike the BLACK DSN which fulfills the role of a mundane telephone system, the RED DSN is a high security communications system designed for classified and other highly sensitive data.

GTE Government Systems designed and built the DRSN and still holds most of the contracts for maintenance and security analysis of the RED network.  They're also happy to give out colorful diagrams and paperwork to anyone who asks.  Raytheon E-Systems is the main switch vendor.

Hardware

The Defense RED Switch Network (DRSN) currently consists of a core of Raytheon Secure Digital Switches interconnected and maintained by government personnel (specifically the DRSN Ops Branch) and GTE Government Systems employees.

Medium Digital Switches and Digital Small Switches are used as peripheral switches for small or temporary installations where installing a DEC Alpha would be difficult or impossible.  STU-IIIs are the standard red telephone set.  These sets are connected to the switch by physically secured, unencrypted local loops forming so-called "RED enclaves."  Encrypted T1 trunks interconnect RED switches between enclaves.

Control

(The following information is sketchy.  Resources on the DRSN are contradictory about its control.)

The DRSN control hierarchy is three tiered.  Groups of switches are directly controlled on a local level by a set of Regional Control Centers (RCC) scattered around the theater.  The RCCs are in turn provisioned by the RED DIMSS, which is in turn monitored by the Manager Of Managers system for faults.  All alarms are catalogued in a central database at this level.

The DRSN maintains Multi-Level Precedence Preemption (MLPP), a slick military term for priority routing of calls, with an additional feature called Ruthless Preemption (flash override-override).  This is a level of call precedence that will route over all other calls.  Access to this feature is understandably tightly restricted.

Numbering

DRSN switches have a unique numbering scheme involving four types of numbers.

Hotlines:  These are five-digit numbers that are generated within a switch that will allow calls to be set up in a point-to-point manner.  Hotlines are numbered from 10,000 to 17,999.

Psuedos:  These are five-digit numbers that are used internally within a switch for the processing of preset conferences.  These numbers are assigned to boards created by software only.  18,743 to 18,999 are used for pseudos.

Trunks:  These are five-digit numbers that are used to interface a switch to the DRSN.  Numbers 19,000 to 19,999 are reserved for trunks.

Subscriber Directory Numbers (SDNs):  These are four-digit suffixes (NPA-NXX-XXXX) that are assigned to the individual users.

DISA is in the process of testing new switches for the DRSN.  The Integrated Command Switch, Small Portable Switch, Medium Digital Switch, and Digital Small Switch.  All switches are designed to interface seamlessly with the existing DSN, DRSN, high-band satellite, and current tactical phone networks.

The DRSN BBS can be reached via Telnet at drsnbbs.ncr.disa.mil.  This BBS serves as the main distribution site for the DRSN directory.  This isn't a public BBS and getting an account is a tight process.  Actual BBS security is unknown.