Introduction
Modernization and integration of shipboard voice communications systems are long overdue. This is true of interior communications with a mixture of analog and digital telephone and general announcing and wireless systems. It is especially true for exterior communications, which include secure dialup services and secure tactical radios. Both must be modernized to enable Navy seagoing platforms to operate effectively as extensions of the Global Information Grid (GIG) in net-centric warfare.
There are operational, programmatic and economic reasons to modernize. Operationally, shipboard voice communications are stuck in an unwieldy and inflexible mixture of analog and digital devices and networks. These systems evolved to provide specific voice communications services without an overall framework to tie them together.
This has led to the present situation in which ships have a mixture of voice devices and systems which function like stovepipes that are difficult and expensive to support and do not provide interoperable networked communications. This is especially true for tactical secure voice. Unlike interior voice systems, which can use equipment based on public telephony standards, tactical secure voice is a loosely coupled set of military unique systems.
At the time of fielding, each individual system met valid operational requirements, but the supporting infrastructure for all these systems was built on an ad-hoc basis that was largely outside the formal requirements process. From a programmatic perspective, this lack of coordination is what makes modernization difficult. Shipboard communications are moving toward the integration of all services over a common network. Programmatic responsibility for specific services and devices must now be either partially or wholly subsumed into a broader program to assure a unified effort.
Similarly, the development and fielding of the infrastructure for shipboard voice communications must now become a broader and more formal process. Migration should become a system-engineering task with a specific long-term goal and a phased implementation plan or rolling baseline. This task should begin with an understanding of the operational requirements and the capability of meeting them in an integrated environment. Typically, development requires translating user requirements for an existing voice capability that spans from a handset to a radio into a specification for a service distributed across an open architecture network.
Strategy for Development and Deployment
This strategy to develop a plan for unifying and modernizing shipboard voice communications provides a guide for integrating the many voice services afloat into manageable increments.
The long-term goal is to provide improved shipboard voice communications with less expense and less maintenance while still being able to continually improve these services in the future. The method will be to consolidate stovepipe services onto a common network that supports all the appropriate existing operational requirements and yet adds new and flexible capabilities through a life cycle integration process.
One of the main difficulties of integrating voice services is the need to provide adequate security. This difficulty is compounded for shipboard voice because of multiple and changing levels of security and the simultaneous need for low latency and highly reliable, available and survivable communications. There is also the need to integrate secure coalition communications over these same networks and supporting devices.
There are two ways to approach the security problem. The first, which is not aligned with net-centric IP-based design, is to run separate networks at each classification level. This approach is counter to integration because of the difficulty in communicating across the security boundaries, both on and off ship.
The second approach is to encrypt all classified voice traffic and share a common, unclassified network; often called a “black” network. A black shipboard voice network, coupled with interworking functions (IWFs) that act as gateways between the network and the legacy voice systems, supports the consolidation of voice services in controlled phases. Once consolidation is complete, this common backbone will provide interoperable multi-level communications.
A measured, controlled transition process will significantly lower the risks associated with wholesale transition and replacement of the current mishmash design to provide a fully inte¬grated net-centric design. Wholesale replacement supporting digital upgrades of voice systems has been tried in the past with limited success.
These total replacements of analog voice stovepipe systems with an integrated digital telephony-based system required significant unanticipated design modifications resulting in tremendous cost overruns and lengthy schedule slips.
A complete transition to voice-over-IP (VOIP) would be equally challenging. These digital telephony-based examples serve as a valid reminder of the significant pitfalls and increased risk associated with complete replacement and integration of all the voice services at once. The proposed incremental process migrates voice capability to a dedicated black shipboard voice network as a key risk transition mitigation strategy.
The process includes thorough testing of critical operational requirements at each stage of incremental implementation for the integrated voice capability on the black shipboard voice network. An incremental, controlled, fully tested implementation is the best process to fully achieve strategic net-centric goals while maintaining quality and reliability of critical and essential tactical operational voice-based capabilities during the transition process.
The fundamental idea is to initially replace interior voice services with a voice-over-IP service and then incrementally add the exterior secure voice services. The intention is to incorporate each existing voice system as a separate capability, isolating technical risk. If the requirements for implementing a capability cannot be met using VOIP, an interim interworking function will be used to at least provide connectivity to the voice system.
The risk mitigation approach will require an isolated, unclassified shipboard IP network with ports wherever a voice service is needed on the ship. It will also require ports in spaces in which both tactical interworking functions and interior voice IWFs will be located, for example, in the radio room, with at least one port for each radio or interior interworking function. This approach will require a network manager and a cryptographic key management system to support the VOIP terminals and encryption engines for each interworking function.
The VOIP terminal should be modular in design to incorporate a removable encryption engine and certain other military unique features for secure and tactical operations. For classified voice traffic, encryption between user terminals and/or at the interface level for legacy voice systems will be used. In unsecured spaces aboard ship, the encryption module can be removed or deactivated for unclassified use only. Figure 1 illustrates secure voice nodal connectivity.
Since tactical voice spans several security levels, integrating it into a common network requires end-to-end encryption to prevent mixing classified and unclassified information. Unfortunately, there is no simple way to do this with the tactical secure voice systems as they are now. Currently, voice is distributed throughout the ship as red analog signals and is only encrypted near the radios for transmission off the ship.
In the initial phase of consolidation, the tactical devices must be accessed through a series of interworking functions attached to the network. These IWFs will receive the classified analog voice from the exterior encryption device. The IWFs will digitize and re-encrypt the voice at the same classification level for transmission over the black shipboard voice network to the user’s VOIP terminal. There will be a complementary reverse path for outgoing voice.
In later phases, legacy systems can either be left as they are or more fully integrated depending upon needs and resources. This method of spiral development will have the flexibility to adapt to changing time lines in the overall program and isolate both technical and programmatic risks.
The process of integrating legacy secure voice systems can be simplified through coordination with crypto modernization efforts such as the VINSON/ANDVT (Advanced Narrowband Digital Voice Terminal) Crypto Modernization program being led by the Air Force.
The integration process requires that various functions of these tactical secure voice cryptos (voice compression, encryption, modem control, input/output devices, etc.) be moved from legacy devices and distributed across the shipboard network and into the user’s voice terminal. This requires modularity in both the VOIP terminal and the modernized crypto so that the appropriate internal crypto functions can be moved at each stage of consolidation.
Modularity at both ends of the network allows certain legacy functions to be bypassed without reengineering and re-installing hardware at each stage. It also meets joint requirements for unclassified infrastructure with plug-and-play-and-remove information assurance capabilities.
Once the exterior encryption and related functions are performed at the user terminal the legacy devices can be phased out. This is the point that modernization of the tactical voice systems can finally begin. Legacy radios can be replaced with next generation radios, and the interworking functions can be replaced by routers that will handle the integrated voice traffic. A standard for secure voice interoperability can be used as the basis for replacing the various legacy voice encoders and encryption algorithms with a single variable rate voice encoder and encryption method to provide universal secure voice interoperability.
A similar and less complicated process can be followed for integrating the various interior voice services that are also accessed via IWFs, for example, the general announcing system and wireless phones. At the point in the consolidation process when all or most of the voice services are running over a common network the consolidation with the data networks can begin.
In addition to resolving secure voice issues, the unified secure voice approach complements parallel efforts to reallocate wideband satellite communications resources to IP, which provides the following advantages. Converged IP WAN makes efficient use of bandwidth by:
• Allocating all wideband SATCOM resources to IP;
• Allowing the dynamic allocation of all bandwidth;
• Eliminating the 2 megabits per second throughput limitation;
• Reducing ship and shore footprint and life-cycle cost; and
• Eliminating the 1.544 megabits per second bottleneck pierside.
Secure Voice Connectivity at Lower Risk and Cost
An incrementally phased approach for migrating legacy voice systems to VOIP, will simplify shipboard voice modernization. It will provide improved capabilities with lower overall risk and cost. The main components of the initial consolidation phases are a modular VOIP terminal and a set of interworking functions that all have an encryption capability. This capability allows the use of a single, unclassified shipboard network and removes the restriction imposed by separate security levels to support common interoperable, distributed voice communications services.
Leveraging crypto modernization programs will also simplify the modernization process and lower both the risk and cost. As consolidation progresses, shipboard voice services, especially the secure tactical systems, can be modernized or replaced.
They can also be expanded to support converging real-time services as extensions of the GIG in net-centric warfare. A parallel secure enclave concept will be coordinated to assure extended secure voice support for Marine air-ground task forces in their Operational Maneuver from the Sea missions.
Mr. Thomas Moran works in the Voice Systems Section of the Naval Research Laboratory.
Ms. Yuh-Ling Su is the secure voice assistant program manager in the Networks, Information Assurance and Enterprise Services Program Office (PMW 160) under the Program Executive Office Command, Control, Communications, Computers and Intelligence (PEO C4I).