Evaluation of Message Broker Approaches for Information Exchange in Disadvantaged Tactical Networks in a Federated Environment

Abstract

The research task group NATO STO/IST-150 «NATO Core Services profiling for Hybrid Tactical Networks» is working towards profiling Core Services for the tactical domain, which can be described as DIL (disconnected, intermittent and limited) environments. In this context, our work is intended to feed into future spirals of the Federated Mission Networking (FMN) concept, which, until recently, has been mostly focused on fixed/stable infrastructure networks. In IST-150, we specifically address information exchange needs of deployed coalition forces. Hence, our work is an enabler for the future of command and control systems, which will need to use efficient and appropriate solutions that ensure timely delivery of data and information superiority up to the last mile. In IST-150 we have analyzed and experimented with several message broker mechanisms for information exchange, including the NATO recommended WS-Notification standard for publish/subscribe. We have found that the Message Queuing Telemetry Transport (MQTT) industry standard exhibits low overhead and is worth further studies. In this paper, we continue our analysis in the application of MQTT to tactical networks. We pursue a comparative experiment between three different approaches to sharing data in a federation. Two of these approaches involve multiple MQTT brokers, using the MQTT bridge and a bespoke MQTT mesh approach, respectively. The third approach is a serverless solution based on UDP. The paper investigates these approaches from a performance viewpoint, varying characteristics such as data exchange frequency, network delay and packet loss in an emulated tactical network. The data exchange consists of Blue Force Tracking information transmitted by all units. We present the obtained performance results between brokers considering the different network characteristics. Importantly, we identify the brokers’ advantages and bottlenecks allowing a better understanding of the conditions in which they can be deployed.