1	Using Simulation to Evaluate Traffic Engineering Management Services in Maritime Networks David Kidston and Thomas Kunz October 25^th, 2006
2	Presentation Overview A Definition of Maritime Networks Motivation The Maritime Model The Management Services Results Conclusions and Future Work
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4	Maritime Network Characteristics
5	Motivation Since maritime units operate in a low bandwidth environment with varying communications capabilities the efficient use of bandwidth and effective exchange of information is essential While different applications are converged onto a single network they do not all have the same value. Traffic engineering (TE) can be used to ensure that critical information is delivered before less urgent traffic. In order to evaluate potential TE services in maritime networks, modeling provides a low cost alternative to implementation.
6	Maritime Model - Topology Small Network The connectivity of the small network model showing all the wireless links is shown Based on the description of a single naval task group on patrol Large Network A straightforward extension of the small network, except with two naval task groups The second task group has two high speed satellite links instead of one
7	Maritime Model – Mobility Model Intra-task force mobility Based on the Nomadic Community model where the individual nodes of each task group move randomly within 3 nm of their base position Links fail when they exceed 18 nm. Inter-task force mobility The two task groups begin 18 nm away from each other (at the closest point) and at a random arrival angle. The first task group then approaches the other steadily at a relative speed of 30 knots (nm/hour) on a set heading evenly distributed from this trajectory angle of -45° to +45°
8	Maritime Model – Traffic Model The nominal load model was made to match as closely as possible the background traffic seen during a maritime exercise (“in” is towards the maritime node) The high load model is based on the assumption of increased traffic at times of increased activity.
9	Management Services Traffic Monitoring Service (TMS) Designed to measure the incoming and outgoing traffic of a node and distribute this information in summary form to all other nodes (at a varying level of detail) Traffic Prioritisation Service (TPS) Provides a mechanism to rank traffic by importance and prioritise resource allocation accordingly using DiffServ Adaptive Routing Service (ARS) Provides load balancing and matches application traffic classes to network resources, determining what types of traffic must/should travel over a certain type of bearer
10	Results (TMS) Based on the topology, mobility and background traffic described the TMS was simulated in OPNET The effect of increased load is readily apparent in maritime networks, with the TMS delay almost doubling from nominal to high background traffic Enhanced and detailed modes have a long delay which may be acceptable if the information is not being used interactively Unlikely to be sufficient for problem solving purposes
11	Results (TPS) Use of the DiffServ weights shown gave a significant improvement in the TMS delay. Improvement of approximately 20% at saturation and approximately 33% at high load were seen. This confirms that DiffServ-style QoS can make a significant improvement to prioritized flows in the Maritime environment. Further studies in OPNET could be completed to determine the impact of alternative WFQ weightings.
12	Results (ARS) Without TPS or ARS, the delay of two voice calls from the NOC were both 1.4 +/- 0.3 seconds at high load, far less than an generally accepted maximum of 500 ms. In order to improve utilization of the network, an MPLS overlay was introduced to allow traffic travelling to Ship 4 to take different routes depending on the application type and priority. In this case high priority voice traffic was to travel via Ship 3 while all other traffic will travel over the default route via Ship 1. With the combination of TPS and ARS, the impact on the delay of voice packets is significant. The high-priority voice call which is taking the alternate lightly loaded route via Ship 3 has a delay of 0.19 +/- 0.03 seconds while the lower priority voice call which uses the default route has a delay of 0.43 +/- 0.10 seconds.
13	Conclusions and Future Work Management services were shown to provide concrete improvements TMS – Monitoring service with variable overhead and delay TPS – Prioritisation service gives 20-33% improvement ARS – Adaptive routing provides load balancing Simulation provides low cost alternative to real-time deployment and testing Results are only as good as the model Currently using maritime model to investigate guaranteed reservation service