Real-World Secure, Converged Network Interoperability for the U.S.-Joint Coalition Environment
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Military communications today are diverse and converged technology networks. The convergence of tactical and strategic networks around a broad range of technologies, including VoIP, TDM, SATCOM, cellular, tactical radios, SCIP cryptographic devices, WiFi, and WiMAX, make it a very challenging heterogeneous environment in which to deploy, network and operate. The “real world” of military communications for years to come will be a diverse and converged network including IP, TDM, and other legacy or emerging technologies.
Joint interoperability of these converged networks is a significant problem across the U.S. military services, as well as among NATO allies and Coalition partners. Among the challenges is the severe lack of interoperability between the users of VoIP and TDM networks. Warfighters today are divided by networks that do not lend themselves easily to interoperability, so that warfighters in the IP world, for instance, can’t reach warfighters located in the TDM world and vice versa.
Placing a secure, point-to-point call in this kind of segregated communications environment has been a difficult problem to resolve, especially with the challenge of ensuring that multi-technology networks are interoperable and provide a secure link between disparate networks. However, the solution for U.S. Joint, NATO, and Coalition interoperability must be based on published standards and utilize off-the-shelf fielded encryption devices, all of which are the key to a successfully converged communications network and successful missions.
Introduction
Thanks to published standards, secure and interoperable C2 communications is now possible. At NATO’s 3rd Secure Communications Interoperability Protocol (SCIP) Experimentation held October 27–29, 2008 in The Hague, the participants were able to successfully demonstrate secure end-to-end communications between the different manufacturers’ IP and TDM terminals.
The success of secure calls at NATO’s 3rd SCIP Experimentation between terminals on separate but interconnected PSTN/ISDN, Analog and IP circuits and networks demonstrate that establishing secure interoperability is now a proven capability. This Secure VoIP - Secure TDM interoperability using published standards is critical during the global transition from circuit-switched networks to packet-switched networks.
Specifically, the use of ITU’s V.150.1 (Modem over Internet Protocol) to support IP to TDM interoperability of SCIP-encrypted secure voice is a valuable tool for converged networks supporting secure voice requirements. In addition, the compatibility between the different SCIP technologies, wired and wireless, allows for secure access and interoperability to tactical radio, which demonstrates that seamless, secure interoperability between fixed and mobile tactical military users is also a capability to be deployed in support of a joint operating environment.
Linking IP and TDM
To date, the military has been trying to perform patch work to get the IP and TDM worlds to interconnect with each other. However, the separation between circuit switched and packet switched networks is so vast that in some cases warfighters in the field are forced to buy commercial cellular phones to coordinate their activities, because trying to link together the disparate networks is almost impossible.
Tour a typical Tactical Operations Center and you’ll find multiple phones from different networks that are not interconnected. Standard procedure is to hand off calls from one warfighter to another in order to reach across the chasm of networks. However, based on the published Session Initiation Protocol (SIP) standard, technology exists today to deliver easy-to-use, seamless, secure tactical and strategic VoIP - TDM interoperability.
Solving today’s interoperability problem is directly tied to published standards and interfaces. These VoIP and TDM standards and interfaces are the key to achieving joint interoperability across the military services, as well as among America’s allies and coalition partners. Technology has evolved to the point where warfighters can pick up the phone, dial the required digits, and have their calls go through, regardless of whether they (or the intended recipient) are using IP-based or TDM-based phones.
V.150.1 and SCIP
Modem traffic over both circuit-switched networks and packet-based networks is a requirement for today’s real-world hybrid networks. Modem over Internet Protocol (MoIP) technology ensures that as networks migrate from TDM to an IP infrastructure they are still able to handle calls generated by dial-up modems or initiated for an encrypted IP phone. In order to support Secure VoIP ↔ Secure TDM user calls, the modem in the analog voice encryption device must be satisfied.
The challenge was creating a standard for IP networks that supported dial-up modem calls. This has been accomplished with the ITU’s publication of the V.150.1 standard, which defines how to relay data into and out of an IP network via a modem. One of the benefits of the V.150.1 modem relay application is that it requires significantly lower bandwidth, compared to G.711, when interconnecting via IP transmission to SCIP devices located in TDM networks.
Diagram 1: V.150.1 Modem Relay Application
SCIP is a standardized framework to allow end-to-end encryption over heterogeneous networks.
A SCIP device has a myriad of benefits for a number of communications scenarios including single-dial access to Voice over Secure IP networks. A SCIP user in a non-secure network, VoIP or TDM, can have a daunting challenge locating and navigating through a VoSIP Gateway to connect securely with a SIP user. Imagine, for instance, being locked away in a SIP network and not being able to quickly, easily and securely access the person you need to speak with outside the network or vice versa.
However, a warfighter located in a non-secure VoIP or TDM network using a SCIP device can simply dial the published user’s station number and the secure call will be translated correctly and delivered to the user. No secondary dial tone or over-dialing is required in this scenario. The REDCOM Advanced Secure Gateway Application was most recently demonstrated and documented at JUICE 2009.
Below is an Advanced Secure Gateway Application (diagram 2) that lays out the many possible secure call strings.
Diagram 2: Advanced Secure Gateway: Single Dial Interoperability
3rd SCIP Experimentation
NATO’s 3rd SCIP Experimentation consisted of a number of heterogeneous networks including ISDN, PSTN, GSM, VoIP and tactical radio. The network configuration provided for the 3rd SCIP Experimentation was similar to that used the two previous years, but with provision of IP–ISDN interfaces. Additionally, the network was extended with a small GSM “pico-cell” and a tactical radio network.
Two REDCOM SLICE® 2100™ switches with TRANSip® supporting V.150.1 were utilized for the 3rd SCIP Experimentation. The REDCOM SLICE 2100s were connected via an IP trunk. One SLICE 2100 was also connected to the NATO Consultation, Command and Control Agency (NC3A) TEMPLE Laboratory via an E1 connection (this allowed a connection to the reference networks for NATO circuit-switched strategic networks). The other SLICE 2100 was connected via IP to a GSM pico-cell (diagram 3).
Diagram 3: NATO SCIP Experimentation 2008
An additional IP switch was provided by NC3A. This was connected to the IP side of one SLICE 2100, and through the IP infrastructure in the TEMPLE Laboratory (providing a connection through the reference networks for NATO packet switched strategic networks). A tactical radio network was connected to the NC3A- provided IP LAN.
Successful secure calls were established between the various SCIP enabled devices.
Conclusion
NATO’s 3rd SCIP Experimentation in October 2008 clearly and successfully demonstrated SCIP calls between circuit-switched SCIP terminals on PSTN or ISDN networks and packet-switched SCIP terminals on IP networks.
The success of secure calls between terminals on PSTN/ISDN and IP networks is great news for the U.S. military, NATO allies and Coalition partners, who are searching for ways to achieve secure interoperability during the transition from circuit switched to packet switched networks. The use of the V.150.1 modem over IP capability to support IP to TDM interoperability of SCIP encrypted secure voice has been successfully demonstrated as a viable option for providing both security and interoperability.
In addition, the success of NATO’s 3rd SCIP Experimentation demonstrated the value of an integrated VoIP and TDM switch within a single platform (REDCOM SLICE 2100) acting as a proven SCIP Gateway, while supporting V.150.1 with an integrated SIP Call Manager with IP Trunking, Media Gateway and Media Gateway Controller capabilities.