Larry Wong

Experience-with autoconfiguring a network with IP addresses

To make future tactical battlefield networks more agile, flexible and robust, nodes must rapidly configure themselves with little or no human intervention,moreover they must reconfigure automatically as the environment changes. We present our approach to configuring and reconfiguring an entire network domain, possibly consisting of tens of thousands of hosts and routers, based on a new dynamical configuration distribution protocol (DCDP). DCDP automatically distributes address-pools and other IP configuration information to every subnet in a domain, where a subnet configuration protocol can configure each node in a subnet. This paper describes the first implementation of DCDP and shows how, with the subnet configuration protocol DRCP, it rapidly configured IP addresses to Linux hosts and routers.

Ad hoc mobility protocol suite for the MOSAIC ATD

An ad hoc mobility protocol suite (AMPS) aimed at providing rapidly deployable, secure, robust IP-based communications among tactical mobile ad hoc nodes is presented in this paper. AMPS is an integrated networking solution for the MOSAIC ATD in that it provides the following capabilities: autoconfiguration, mobility management, unicast and multicast routing, reliable transport, quality of service, security and network visualization tools. This paper describes the architecture and implementation of AMPS for the MOSAIC ATD. Both laboratory and field experiments to measure AMPS functionality and performance were conducted in 2002 and 2003. This paper reports on the results of those experiments and their impact on future AMPS design and operation.

Bandwidth broker architecture for VoIP QoS

We present a scalable architecture for assuring Quality of Service to VoIP applications in an Internet Service Providers network. This architecture is based on the Differentiated Services and Bandwidth Broker models, and can also be used by other resource-sensitive applications. In this paper, we elaborate on a number of significant issues involved in the design, implementation, deployment and use of the Bandwidth Broker. The Call Agent architecture is used as the VoIP application. We describe the Bandwidth Broker prototype that is used to validate our approach. Our findings suggest that it is feasible to use the Bandwidth Broker architecture for assuring QoS, and a trade-off exists between the granularity of resource requests and call-setup delay.

Robust router reconfiguration in large dynamic networks

In the current IP protocol suite there is a tradeoff between scalability and the maximum allowable mobility. Flat MANET routing protocols can deal with high mobility, but cannot scale to support the thousands of mobile routers needed in the Armys Future Combat System. Using IP subnets and hierarchical domains provides scalability, but breaks existing configuration protocols (A. McAuley, et al., 2002) in high mobile networks (e.g., network splits lead to conflicting routing tables). This evidences the need for router mobility detection and dynamic reconfiguration mechanisms in scalable mobile networking. This paper describes a new beacon protocol to allow rapid detection of IP router movements, including network splitting and merging, within large hierarchical domains. It detects movement by identifying each IP subnets and higher-level domains with a beacon node; and, by not relying on network configuration, IP routing, or any fixed nodes, it is robust to any network changes. Nodes can optionally report topology changes to the beacon node with low overhead.

Network Layer Congestion Control to Ensure Quality of Service (QoS) in Secure Battlefield Mobile Ad Hoc Networks

To address the quality of service issues in a mobile ad hoc network (MANET) for the diverse set of applications that are carried in the network, the US ARMY CERDEC PILSNER program utilizes a Congestion Control Agent (CCA) as the focal point to facilitate QoS control in a MANET. The main functionalities of CCA include monitoring the traffic loading and queue size status of a router, and based on the measurements, CCA controls the router behavior through dynamically resetting the Weighted Fair Queuing (WFQ) and Random Early Detection (RED) parameters. In this paper, we first describe the main functionalities of CCA, including (1) Dynamically computing the RED parameters¿by measuring the queue size statistics, RED parameters are dynamically adjusted based on the congestion status, such that TCP congestion window is appropriately controlled. (2) Dynamically computing the WFQ parameters¿WFQ parameters are adjusted according to the measured traffic loading for the traffic classes and precedence levels. The underlying algorithm is designed to satisfy the Multi-Level Precedence and Preemption (MLPP) requirement that is unique to military applications. We investigate the performance gain achieved by CCA using OPNET simulation. We show that CCA can manage the MLPP requirements and improve the user-perceived QoS measures like throughput and call success rate.

Generic protocol for network management data collection and dissemination

YAP is a protocol designed to efficiently and robustly relay network configuration states of nodes to a designated node that collects and stores the configuration states of all the nodes. Once the configuration states from the nodes are collected, any application can query the information to perform its own specific function. For example, a GUI application can query the database to display the logical topology of the networks. Also a Configuration Manager can query the database to decide how to reconfigure the network. We describe how YAP was integrated with protocols designed to auto-configure IP-related attributes of nodes (using DRCP and DCDP).

Realistic wireless emulation for performance evaluation of tactical MANET protocols

Traditional approaches for testing MANET protocols and applications prior to field experimentation often involve simulation tools or small-sized physical testbeds. However, simulation tools typically do not run in real-time and rely on simplified models rather than a real system, while physical testbeds are prohibitively expensive to build and operate. A more practical method is to use emulation tools as they provide high-fidelity network modeling in a cost-effective manner without sacrificing realism. In this paper, we present the use of Wireless IP Scalable EmulatoR (WISER) and its capabilities for testing and evaluating two network routing agents, namely Congestion Control Agent (CCA) and Soft Handoff Agent (SHA), developed for tactical MANETs under the CERDEC PILSNER program. These two agents are integrated within the WISER framework, providing them a scalable and realistic wireless MANET testbed which otherwise was not readily available. Experiments demonstrating interoperability of these technologies are included.

Enhancing application performance with network awareness in Tactical Networks

This paper presents Telcordias Network Awareness Service (NAS), a suite of network sensing technologies that allows applications to adapt to medium-to-long time scale performance variations in mobile tactical wireless networks. NAS is a working software prototype developed for the purpose of measuring, estimating, and inferring network metrics that impact application performance such as congestion level, packet transmission loss rate, and available path capacity. The prototype operates in a distributed manner, publishing its metrics to tactical network applications operating on protected (so-called “red-side”) computing systems, and is compatible with communication security (COMSEC) considerations that prohibit direct monitoring of network elements on the encrypted side (so-called “black-side”) of tactical radio networks. Each NAS instance performs the following key high-level functions: (1) Collection/measurement of raw packet performance data, (2) inference of network performance metrics and (3) reporting of network performance to other NAS instances and tactical applications. NAS has been successfully integrated and demonstrated as part of the U.S. Office of Naval Research Limited Technology Experiment (LTE) at SSC-Charleston in the summer of 2010. Experimental results reported here for NAS provide proof-of-concept validation of its ability to afford timely, accurate network awareness for tactical applications, and illustrate the benefits of network awareness to command and control applications in Naval settings.

A Simple Admission Control Algorithm for IP Networks

We present a simple and scalable admission control algorithm for improving the Quality of Service (QoS) in Internet Service Provider (ISP) networks. The algorithm is novel in that it does not make any assumptions regarding the underlying transport technology (works at the IP layer), requires simple data structures and is low in operational complexity, can handle IP network topology changes efficiently, and can help identify congested links in the network. We have verified the working of this algorithm by simulation for arbitrary IP network topologies, and have found it to be successful in performing admission control and identifying congested links after route changes.

Congestion awareness in tactical wireless networks: Discerning congestion-induced losses from wireless link effects

Efficient congestion detection represents an unsolved challenge for tactical networks. This paper presents an edge-based packet probing technique to detect congestion that incurs modest control overhead. The approach presented, herein, is “Differential Performance Packet Probing” (DP3) and leverages the differential treatment of packets at the queues of routers and radios. By measuring loss rates across different types of probe packets, DP3 can detect congestion events and, furthermore, distinguish packet losses due to path congestion events from losses due to link outage events. Extensive results are reported for lab experiments of the DP3 concept in an emulated wireless network environment and in a wired Cisco environment. Detailed statistical analysis of the tradeoff between reliability and agility of the DP3 congestion indicator is also described.