A combined network: asynchronous-transfer mode, tactical high-speed data network and legacy mobile-subscriber equipment

by CW2 Curtis Newkirk and MAJ Linda Jantzen

Recently, during III Corps� Battle Command Training Program Embedded Warfighter Exercise, 3d Signal Brigade had the opportunity to combine the Army�s newest tactical-communications systems with some of its oldest systems into the largest and most complex tactical command, control, communications, computers and intelligence network III Corps has ever installed. Here we outline for fellow Signaleers how we planned and integrated this network.

The brigade installed, operated and maintained the first network that combined legacy, tactical high-speed data network and asynchronous-transfer mode mobile-subscriber equipment into a seamless, robust network capable of meeting the demands of the First Digitized Corps, 1st Cavalry Division, their major-subordinate-command command posts and other units participating in EWFX 2002. The 16th Signal Battalion, 13th Signal Battalion, 57th Signal Battalion and 249th Signal Battalion � with elements from 124th Signal Battalion � deployed a network consisting of six ATM node centers, 18 ATM small extension nodes, seven THSDN NCs, 26 THSDN SENs, three THSDN large extension nodes, three legacy NCs, one legacy LEN, six legacy SENs and 14 radio-access units.

Transmission systems were augmented with two TSC-85 and four TSC-93 tactical-satellite terminals, TRC-170 (tropospheric scatter) and nine TSC-154 terminals (secure, mobile, antijam, reliable, tactical terminals). Unique switching systems in the network included the Modular Transportable Communications System and two Vantage commercial digital switches.

Network planners and controllers at 3d Signal Brigade, 16th Signal Battalion and 13th Signal Battalion used integrated-systems control, Network-Management System and SNMPc to engineer and troubleshoot MSE links for voice, data and videoteleconferencing traffic. The extremely-high-frequency communications planner at the brigade�s SYSCON used the interim Milstar communications-planning tool to plan and manage the SMART-T network.

The entire network spanned from North Fort Hood to Camp Swift, near Austin, Texas, and covered about 150 miles. Engineering this network to include data as well as voice and battlefield VTC was challenging. Questions arose, such as, �How do you provide high-speed data down to the legacy equipment, which isn�t equipped with high-speed multiplexing cards? How do you combine ATM with lower-data-rate THSDN equipment without creating bottlenecks or degrading services? How do you connect packet switches to the high-speed data network and bridge the gap between the two networks?�

Establishing a seamless and efficient tactical C4I network with this varied array of equipment required extensive planning, coordination and a working knowledge of all systems. Network planners, managers and technicians from 3d Signal Brigade and III Corps G-6 � working with their counterparts in 13th Signal Battalion, 1st Cavalry Division and 249th Signal Battalion, 49th Armor Division (Texas Army National Guard) � honed their skills as integrators of every variety of echelons-corps-and-below Signal equipment to ensure a successful mission.

While the distance between 3d Signal Brigade assets at Fort Hood and 249th Signal Battalion assets at Camp Swift was about 110 miles, the distance in technology was about 15 years. We covered the geographical distance by using super-high-frequency multichannel TACSAT (TSC-85s and TSC-93s) and commercial T-1 circuits. The SHF TACSAT provided a direct higher-to-lower VTC path into the corps MSE network from a 3d Signal Brigade SEN at 49th Armor Division�s CP to an NC at Fort Hood and then channel-reassigned to a SEN at the corps� main CP.

The T-1 circuit was broken out at a group modem at each end to provide 256 kilobytes VTC and 768 kb data between 49th Division�s main CP and Fort Hood�s Battle Simulation Center. The T-1 also provided a 512 kb internodal between 249th�s NC 81 at Camp Swift and 16th�s NC 1 at Fort Hood.

Providing data over MSE presented another challenge. The 249th Signal Battalion�s three NC switches, LEN and six SENs were equipped with first-generation Orderwire Control Unit II�s, packet switch and AN/GRC-226 radios. Therefore we had to adjust for the lack of high-speed data capability at the NCs and SENs. The solution was to install routers in the battalion�s NCs and SENs and to enhance the packet switches by configuring them at a data rate of 48,000 kilobits per second.

Configuring the routers to accept the 148.13 network was done via a router border-gateway-protocol statement. The routers within 249th Signal Battalion�s SENs interfaced directly to the router, bridging the 148.13 and the 148.12 networks. This increased the normal 16-kbps SEN packet-switch link to 48 kbps. This increase in bandwidth by 32 kbps per SEN provided a backup data path and was accomplished with a minimum cost of $7,000 per SEN.

See the linked file to the template for a border-gateway-protocol statement used to configure routers to accept 148.13 network. See the following figure for the 48K SEN layout.

48K SEN 48K SEN.

The 57th and 13th Signal Battalions provided the THSDN portion of the network. The 1st Cavalry Division�s 13th Signal Battalion found a way to exceed the standard THSDN data rate of 1,024 kb by bypassing the transmission group mux/demux restrictions in the line-of-sight Version 3 radio system (AN/TRC-190). By using an LOS(V)1 at an NC to its local port and shooting to a LOS(V)4 at a LEN, 13th Signal Battalion was able to capitalize on the 2,048 kb capability of the enhanced-transmission-group modular orderwire card. In the EWFX network, 13th Signal Battalion installed 2,048 kb links from LEN 46 to NC 41 and NC 44, each providing 1,024 kbps data and 1,024 kbps voice.

The most advanced systems in the network belonged to 16th Signal Battalion � with elements from 124th Signal Battalion � that provided state-of-the-art ATM switches and high-capacity line-of-sight transmission systems. Six ANCSs equipped with a Lightstream 1010 ATM switch, Cisco 7206 router, Cisco 2924 catalyst Ethernet switches, Cisco 2514 Multimedia Conference Manager gatekeepers and the legacy interface adapter/forward-error-correction transmission adapters made up the largest part of the network backbone, supporting 8,192 megabytes between NCs. Fourteen ASENs, similarly equipped � with the exception of the Cisco 2514 found only in the ANCS � provided 2,048 mb to CP subscribers.

The Cisco 7206 router supports multiprotocol, multimedia routing and bridging functions. The Ethernet switches provide connectivity for local-area network users. The Cisco 2514 MCM gatekeeper in the ANCS supported H.323 (Internet protocol-based) VTC. Finally, LIA/FECTA is the adapter between legacy MSE voice and data systems and ATM�s cell-switching capabilities.

Still other unique switching systems contributed to the EWFX network. The corps� communications-support platoon supported the highly automated corps tactical CP with their MTCS and a Vantage digital commercial switch, which provided IP-based telephones. Another Vantage switch was placed in the BSC and will possibly be used in the future to decrease the number of SENs needed to support a simulation exercise of this size. The MSE phone count (digital non-secure voice terminals) in the BSC complex alone totaled 428, requiring eight TSENs and three ASENs to support.

The highest data rates that could be achieved in the network belonged to ATM NCs, which went up to 8,092 kbps. Next highest was between THSDN NCs � up to 2,048 kbps (using 13th Signal Battalion�s technique). When we connected an ANCS to a TNCS, however, the data rate dropped to 1,024 kbps (256 k for data and 768 k for voice). While the TNCS is equipped with a Cisco 3640 router, high-speed FEC circuit-card assemblies and ETGMOW CCAs capable of achieving 1,024 kbps voice and 1,024 kbps data, the limiting factor when interfacing with the ANCS is the ANCS�s HSMUX I card, capable of just 256 kbps data.

In conjunction with lowering the data rates, the ATM switch operator had to patch the digital trunk group to legacy mode. This was accomplished on the A21 patch panel (see the following figure). Network planners had to plan carefully to avoid data �chokepoints� in the network. Overall, subscribers weren�t adversely impacted by the differences in equipment.

Patching diagram Patching for legacy equipment in the ATM NCS.

Transmissions media were the next challenge. A mixture of AN/GRC-245 HCLOS radios and AN/GRC-226 legacy radios in the network meant that soldiers had to become familiar with different troubleshooting techniques and terms used to describe loopback and test procedures applicable to each. HCLOS radios fielded to 124th and 16th Signal Battalions are equipped with over-the-air compatibility, which allows interoperability between the two radios. This was also the case when troubleshooting a TNCS and ANCS. Of the following figures, the top figure gives an example of LOS troubleshooting for THSDN, while the bottom figure gives an example of ANCS troubleshooting steps.

NCS to NCS links 3d Signal Brigade's NCS to NCS links. Note: master of links coordinates these actions at both ends.
ANCS troubleshooting steps Part 1
ANCS troubleshooting steps Part 2
ANCS troubleshooting steps Part 3
ANCS troubleshooting steps (3 parts to this illustration). On Parts 2 and 3, Part 2 depicts the ANCS DTG, while Part 3 illustrates the ASEN ATM node.

Long-haul requirements were met using four TSC-85s and six TSC-93s for internodal links, links to critical CPs and higher-to-lower VTC links. Nine AN/TSC-154 terminals provided more beyond-LOS capability. The SMART-Ts proved to be valuable assets with their fast installation time and ability to add redundancy and robustness to the network. The following figure depicts the satellite network.

TACSAT network TACSAT network for III Corps' EWFX02.

Finally, two AN/TRC-170 tropo systems from 313th Signal Company provided a 1,024 kbps internodal link in 13th Signal Battalion�s network.

Special consideration was given for serial-base VTC, III Corps� command net. In some cases, we used the HSMUX CCA in the NCS to provide VTC as well as data. Channel reassignments and database management were crucial for this mission. All changes of the switch database to support VTC or data paths had to be closely coordinated to avoid disruption of either of these critical services.

ATM SENs are capable of providing data and serial-based VTC simultaneously. However, there were cases in which we had to use the ASEN in legacy mode due to VTC traffic using most of the bandwidth (top figure of the following figures). This normally occurred over satellite links where the bandwidth was restricted to 1,024 K. Examples of these can be seen in the following figures.

Patch panels Legacy patching was employed in the ASEN due to VTC traffic taking most of the bandwidth. The top panel represents a partial view of the ASEN patch panel. The bottom panel is the new modified auxiliary patch panel.
ATM database Example of ATM database.
THSDN database Example of THSDN database.
Channel reassignments Example of channel reassignments.

While they require extensive planning and coordination, legacy, THSDN and ATM MSE can be successfully integrated into a single network, as demonstrated during III Corps� 2002 BCTP EWFX exercise. The fast pace of technological change, however, requires equipment operators, network planners, managers and technicians to keep an equally fast pace of professional training and self-development in the classroom and in the field.

CW2 Newkirk has been 3d Signal Brigade�s network-management technician since June 1999. He holds an associate�s degree from Fayetteville Community College, Fayetteville, N.C. His warrant-officer assignments also include 13th Signal Battalion and 304th Signal Battalion, Seoul, Korea. His enlisted career included assignments as a station technical controller, operations noncommissioned officer in charge, MSE switch operator and platoon sergeant with various units in the United States and Korea, including 589th Signal Company, Stuttgart, Germany; 7th Signal Command, Fort Ritchie, Md.; 275th Signal Company, Seoul; Company C, 11th Air Defense Signal Battalion, Darmstadt, Germany; and Company B, 51st Signal Battalion, Fort Bragg, N.C.

MAJ Jantzen has been the S-3 operations at 3d Signal Brigade since June 2000. She holds a bachelor�s degree in mass communications from the University of Illinois in Chicago and a master�s degree in telecommunications from Michigan State University. A graduate of the Command and General Staff Officer�s Course, she has served in various command and staff positions in the Signal Corps in the United States, Bosnia, Germany, Somalia, Saudi Arabia and Korea. Her assignments include commander, Headquarters and Headquarters Company, 440th Signal Battalion, 22d Signal Brigade, Darmstadt and Lukavac, Bosnia; operations group Signal officer, Combat Maneuver Training Center, Hohenfels, Germany; battalion S-1, battalion maintenance officer and division Signal plans officer, 10th Signal Battalion, 10th Mountain Division, Fort Drum, N.Y., and Mogadishu, Somalia; and platoon leader, 26th Signal Battalion, 93d Signal Brigade, in Operation Desert Storm.

Acronym Quickscan
ANCS � a(synchronous-transfer mode) node-center switch
ASEN � a(synchronous-transfer mode) small extension node
ATM � asynchronous-transfer mode
BCTP � Battle Command Training Program
BGP � border-gateway protocol
BSC � Battle Simulation Center
C4I � command, control, communications, computers and intelligence
CCA � circuit-card assembly
CP � command post
ETGMOW � enhanced-transmission-group modular orderwire
EWFX � Embedded Warfighter Exercise
FEC � forward-error correction
HCLOS � high-capacity line-of-sight
HSMUX � high-speed multiplexing
IP � Internet protocol
K � "shorthand" for kbps, kilobits per second
Kb � kilobyte(s)
Kbps � kilobits per second
LEN � large extension node
LIA/FECTA � legacy interface adapter/forward-error correction transmission adapter
LOS(V) � line of sight (version)
Mb � megabyte
MCM � Multimedia Conference Manager
MSE � mobile-subscriber equipment
MTCS � Modular Transportable Communications System
Mux/demux � multiplex/demultiplex
NC � node center
SEN � small extension node
SHF � super-high frequency
SMART-T � secure, mobile, antijam, reliable tactical terminal
SNMP � simple network-management protocol
SYSCON � systems control
TACSAT � tactical satellite
THSDN � tactical high-speed data network
TNCS � t(actical high-speed data network) node-center switch
TSEN � t(actical high-speed data network) small extension node
VTC � videoteleconference(ing)

dividing rule

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