Robert Cole - Profile on Academia.edu (original) (raw)

Papers by Robert Cole

Three MIBs: • DYMO-MIB <draft-ietf-manet-dymo-mib-02.txt> [1] • SMF-MIB <draft-ietf-mane... more Three MIBs: • DYMO-MIB <draft-ietf-manet-dymo-mib-02.txt> [1] • SMF-MIB <draft-ietf-manet-smf-mib-00.txt> [2]

This study presents an analysis of computer worm propagation in a Mobile Ad-hoc Network (MANET). ... more This study presents an analysis of computer worm propagation in a Mobile Ad-hoc Network (MANET). According to the recent DARPA BAA - Defense Against Cyber Attacks on MANETS (DARPA, 2004), "One of the most severe cyber threats is expected to be worms with arbitrary payload that can infect and satu- rate MANET-based networks on the order of seconds". Critical to

SPIE Proceedings, 2007

The Global Information Grid (GIG) is a collection of systems, programs and initiatives aimed at b... more The Global Information Grid (GIG) is a collection of systems, programs and initiatives aimed at building a secure network and set of information capabilities modeled after the Internet. The GIG is expected to facilitate DoD's transformation by allowing warfighters, policy makers, and support personnel to engage in rapid decision making. The roadmap is designed to take advantage of converged services of voice, data, video, and imagery over common data links. The vision is to have commanders identify threats more effectively, make informed decisions, and respond with greater precision and lethality. The information advantage gained through the GIG and network-centric warfare (NCW) allows a warfighting force to achieve dramatically improved information positions, in the form of common operational pictures that provide the basis for shared situational awareness and knowledge, and a resulting increase in combat power. The GIG Precedence and Preemption (P&P) requirements stem from the need to utilize scarce resources at critical times in the most effective way in support of national security, the intelligence community and the war-fighter. Information Assurance (IA) enables all information and data to be available end-to-end to support any mission without delay in accordance to the sensitivity of the task. Together, P&P and IA ensure data availability integrity, authentication, confidentiality, and non-repudiation. This study addresses and analyzes the QoS and P & P requirements and architecture for the GIG. Threat scenarios are presented and used to evaluate the reference architectures. The goal of the study is to assess the Information Assurance concerns associated with implementing Precedence and Preemption within the GIG and to guarantee an acceptable minimum level of security and protection for DoD networks.

MILCOM 2005 - 2005 IEEE Military Communications Conference

External Border Gateway Protocol (eBGP) is the ubiquitous protocol used today for advertisement o... more External Border Gateway Protocol (eBGP) is the ubiquitous protocol used today for advertisement of reachability information and for route selection among administrative domains (Autonomous Systems or ASs) in the Internet. However, many emerging needs in commercial and military networking have exposed limitations of the current eBGP. In particular, these IP networks of the future will carry a very diverse mix of applications, with very diverse Quality of Service (QoS) requirements (in the broad sense of the phrase). Some of these networks also have a very diverse set of component networks (wireless and wireline, fixed and mobile with different degrees of mobility, long lived and short term ad-hoc) and some of the component networks may be very dynamic in their service capabilities. These scenarios call for enhancing eBGP to allow for multi-topology and QoS-aware routing, using several QoS metrics in decision making. In such an enhanced BGP, more than one route (or path vector) may be propagated in BGP_UPDATE messages, helping optimize with respect to different QoS metrics as needed by different traffic types. In this paper, we discuss such an enhancement of eBGP. We develop details of advertisements, route thinning, and route selection needed to make the eBGP multi-topology and QoS-aware in the sense described above. We take the eBGP and internal BGP (iBGP) advertisement and route selection process and identify any modifications needed at each stage. We also discuss interactions between eBGP and iBGP and between BGP and the Interior (intra-domain) Gateway Protocol (IGP) needed to make the approach work end-to-end. We also discuss alternative ways to ensure that packets follow the selected end-to-end routes (both within and between domains). In particular, the potential uses of MPLS, source routing, tunneling, and DiffServ/ToS bits for this purpose are discussed in the paper.

Address-Identifier Mapping System for scalable routing

2009 IEEE Symposium on Computers and Communications, 2009

The main architectural problem with the current inter-domain routing model is the overloading of ... more The main architectural problem with the current inter-domain routing model is the overloading of IP addresses due to their use for identification, location, and forwarding. This makes it hard to support the need for multi-homing, traffic engineering, and mobility while maintaining address hierarchy that is essential for scalable routing. Thus, there is a need to separate identifiers from locators. In this paper we identify architectural and protocol changes in addressing and routing needed to provide major improvements in scalability. We design a corresponding protocol solution (Address-Identifier Mapping System-AIMS) based on separation of identification and addressing, and a mechanism for mapping ID to address.

Automated discovery of information services in heterogeneous distributed networks

MILCOM 2008 - 2008 IEEE Military Communications Conference, 2008

... Harshavardhana Applied Physics Laboratory Johns Hopkins University Laurel, MD, USA Abstract—T... more ... Harshavardhana Applied Physics Laboratory Johns Hopkins University Laurel, MD, USA Abstract—The Global Information Grid (GIG) will be com-prised of collections of different Service Capability Domains (SCDs). Each SCD offers a set of information services, such as Voice ...

ietf.org

Four MIBs related to MANET WG protocols:• DYMO MIB< ietf-manet-dymo-mib-02. txt>[1]• SMF MI... more Four MIBs related to MANET WG protocols:• DYMO MIB< ietf-manet-dymo-mib-02. txt>[1]• SMF MIB< ietf-cole-manet-smf-mib-02. txt>[2]• NHDP MIB< ietf-cole-manet-nhdp-mib-01. txt>[3]• OLSR MIB< ietf-cole-manet-olsr-mib-01. txt>[4]

Comparative performance of interleaved and non-interleaved pipelining in ATM terminal adapters

Computer Networks and ISDN Systems, 1995

In this paper we compare the end-to-end delay performance of two service disciplines that an Asyn... more In this paper we compare the end-to-end delay performance of two service disciplines that an Asynchronous Transfer Mode (ATM) multiplexor can use to multiplex pipelined synchronous native protocol frames arriving over low speed access lines onto higher speed ATM trunks. The ATM multiplexor must convert native protocol frames on the access lines (typically hundreds of bytes in length) into ATM cells on the trunks (of fixed length 53 bytes) at the network access and the corresponding ATM (de)multiplexor must reassemble these multiple ATM cells into a bit continuous synchronous native protocol frame at the network egress.In one service discipline, the multiplexor (hereafter referred to as a terminal adaptor, or TA) pipelines one synchronous frame at a time onto the high speed trunk, waiting, if it needs to, for the successive ATM cells from this one synchronous frame to accumulate. This scheme introduces a larger queueing delay at the ingress TA but no playout delay is required at the egress TA. In the other scheme the TA interleaves the ATM cells from the various synchronous frames arriving concurrently over the low speed lines. An interleaving scheme has a smaller queueing delay, but introduces a large variability in the network insertion times of the ATM cells corresponding to a native protocol frame. Hence the egress TA must enforce a delay before playing out the original bit-synchronous native frame over a low speed line, so as to increase the probability that the ATM cells are available when required to properly reassemble the native synchronous frame into a bit continuous stream.Using an analytical model for the first scheme and a simulation model for the second scheme we analyze the end-to-end delay of a synchronous frame, and compare the mean end-to-end delay for various trunk speeds (TA-to-network switch) to “access” line speed ratios. We conclude that, for the cases studied in this paper, if this ratio is greater than or equal to 4 then, over the range of useful loading, interleaved pipelining typically yields smaller mean delays than noninterleaved pipelining. If the ratio is less than 4 then interleaving typically yields larger mean delays for native protocols due to increased playout delays at the egress TA.

ACM SIGCOMM Computer Communication Review, 2001

We describe a method for monitoring Voice over IP (VoIP) applications based upon a reduction of t... more We describe a method for monitoring Voice over IP (VoIP) applications based upon a reduction of the ITU-T's E-Model to transport level, measurable quantities. In the process, 1) we identify the relevant transport level quantities, 2) we discuss the tradeoffs between placing the monitors within the VoIP gateways versus placement of the monitors within the transport path, and 3) we identify several areas where further work and consensus within the industry are required. We discover that the relevant transport level quantities are the delay, network packet loss and the decoder's de-jitter buffer packet loss. We find that an in-path monitor requires the definition of a reference de-jitter buffer implementation to estimate voice quality based upon observed transport measurements. Finally, we suggest that more studies are required, which evaluate the quality of various VoIP codecs in the presence of representative packet loss patterns.

This study presents an analysis of computer worm propagation in a Mobile Ad-hoc Network (MANET). ... more This study presents an analysis of computer worm propagation in a Mobile Ad-hoc Network (MANET). According to the recent DARPA BAA - Defense Against Cyber Attacks on MANETS (DARPA, 2004), ”One of the most severe cyber threats is expected to be worms with ...

MANET network management and performance monitoring for NHDP and OLSRv2

2010 International Conference on Network and Service Management, 2010

Proceedings of the 6th international workshop on Software and performance - WOSP '07, 2007

In this paper, we propose a new approach for mitigation of worm propagation through tactical Mobi... more In this paper, we propose a new approach for mitigation of worm propagation through tactical Mobile Ad-Hoc Networks (MANETs) which is based upon performance signatures and software rejuvenation. Three application performance signature and software rejuvenation algorithms are proposed and analyzed. These algorithms monitor critical applications' responsiveness and trigger actions for software rejuvenation when host resources degrade due to a coresident worm competing for host resources. We analyze the effectiveness of our algorithms through analytic modeling and detailed, extensive simulation studies. The key performance metrics investigated are application response time, mean time between rejuvenations and the steady state probability of host infection. We also use simulation models to investigate several design and parameter tuning issues. We investigate the relationship between the rate at which the application performance monitors can detect outof-specification applications and the rate of worm propagation in the network.

MILCOM 2005 - 2005 IEEE Military Communications Conference, 2005

We have embarked upon the development of a reusable Global Information Grid (DID) simulation plat... more We have embarked upon the development of a reusable Global Information Grid (DID) simulation platform in order to support GIG architecture, design and engineering. We followed a classical systems engineering approach to the design of the GIG simulation platform. We have identified a set of useful performance studies to perform related to GIG architecture and design. We present our approach to the design of our GIG simulation platform and the development of a GIG topology model allowing for automated simulation configurations. As an example of the platform's utility, we briefly discuss our initial studies of BGP performance in GIG-like environments. We conclude with a discussion of follow on work on our GIG simulation platform.

MILCOM 2007 - IEEE Military Communications Conference, 2007

In the Department of Defense's (DoD) Global Information Grid (GIG) transport network, packet hand... more In the Department of Defense's (DoD) Global Information Grid (GIG) transport network, packet handling must provide preferential transport to high Precedence traffic under all networking conditions, specifically conditions of resource scarcity, e.g., network overload conditions, while simultaneously satisfying packet scheduling required to meet application Quality of Service (QoS) needs. Our approach to this duality is to enhance Active Queue Management (AQM) techniques to provide Precedence and Preemption (P&P) capabilities and rely upon standard, well studied QoS Per Hop Behavior (PHB), e.g., Weighted Round Robin, Class-Based Fair Queuing, etc., for handling QoS requirements. In this way, when operating under engineered loads, the well known scheduling algorithms support high quality QoS for applications. Under network congestion situations, the enhanced AQM layer provides the necessary P&P preferential packet handling favoring high Precedence-Level (P-L) information. Our scheme allows low order queues (within the context of QoS handling) to plead up to the next higher order queue for help in alleviating queue congestion under periods of communication link overload. We refer to our scheme as the Cross Queue-AQM (CQ-ACM) Scheme. Our scheme can be extended to higher numbers of queues and any type of scheduler in a straightforward manner. Through extensive simulation studies and analytical modeling, we investigate the performance of our CQ-AQM scheme under heavy traffic limits, where Preemption is required. The performance metrics of interest to our analysis are packet delay, packet loss and throughput as a function of the packet QoS class and P&P level. Our previous studies concentrated on general nonflow controlled traffic and showed that our algorithms performed extremely well. In this paper we extend our analysis to flowcontrolled traffic by incorporating TCP traffic models into our simulation studies. We find that the application of our CQ-AQM scheme on top of standard QoS scheduling is effective in simultaneously supporting QoS and P&P transport for TCP flows as well.

2007 IEEE Pacific Rim Conference on Communications, Computers and Signal Processing, 2007

Routing in Mobile Ad-hoc Networks (MANETS) has proved to be an extremely challenging research pro... more Routing in Mobile Ad-hoc Networks (MANETS) has proved to be an extremely challenging research problem due to the high frequency of link changes in wireless mobile environments. Most known routing protocols struggle to maintain complex routing structures, e.g., N spanning trees, or use expensive (from the perspective of communications cost) methods for path discovery. These methods incur extreme communications costs in most MANET deployments. In this paper, we investigate the performance of a relatively unstudied class of routing protocols which we refer to as Beacon-Based Routing Protocols. This class of protocols maintain minimum routing structures and use these structures to boot strap path discovery. In a well defined sense, this class of routing protocols achieves optimal performance with respect to minimizing the communications costs associated with on-demand routing. We specifically investigate the impact of multiple tree implementations for path discovery and analyze their impact on the effectiveness of optimal path discovery.

Lecture Notes in Computer Science, 2006

We investigate the performance of of several protocol enhancements to the On-Demand Secure Byzant... more We investigate the performance of of several protocol enhancements to the On-Demand Secure Byzantine Routing (ODSBR) [3] protocol in the presence of various Byzantine Attack models. These enhancements include a) Nodal Weighting (in addition to Link Weighting) in the reputation database, b) a network layer retransmission capability and c) modifications to the packet flow rates. These enhancements are meant to improve the learning rate of the protocol in the presence of various Byzantine Attack models. The attack models investigated include previously investigated models [4] and a new and effective attack model, termed the MAC-Level Attack. We investigate the dynamics of the ODSBR protocol and its enhancements through analytic models and extensive simulation studies. We find that the protocol enhancements improve the learning times of the ODSBR protocol. The Nodal Weighting enhancement specifically helps in the presence of the various colluding Byzantine Attack models investigated. However, the time to develop a relatively complete reputation database in the MANET context is found to be relatively large.

MILCOM 2007 - IEEE Military Communications Conference, 2007

The U.S. Department of Defense's (DoD) warfighter is reliant upon the development of a reliable, ... more The U.S. Department of Defense's (DoD) warfighter is reliant upon the development of a reliable, resilient communications capability under harsh, battlefield environments. Due to high mobilities and the nature of the various terrains, the dynamics of the communications links is extremely erratic and rapidly changing. This results in extreme strain on the performance of routing protocols attempting to find and maintain viable communications paths. In this paper we discuss and analyze a new class of routing protocols which we refer to as Beacon-Based Routing protocols. Beacon-Based Routing protocols proactively build a small number of, typically one or two, spanning trees in the network and use these trees to discover paths on demand. The existence of one (or more) spanning tree(s) ensures full network connectivity and hence can be used to find network paths without the need for network-wide broadcast of discovery messages, as in other on-demand routing protocols. This class of routing protocols represents the generalization of the Pulse Protocol [1], originally developed in 2002 for applications to Internet access networks. The performance of the Pulse Protocol was analyzed in [1] and [2] in various applications including general Mobile Ad-Hoc Networks (MANETs) and in sensor networks. As we discuss in this paper, the Beacon-Based Routing protocol class has optimal behavior with respect to the communications overhead required to run the protocol. As such, its scaling behavior is superior to other existing routing protocol classes when assessed in the context of a MANET. Further, the performance of the protocol is discussed in the specific context of traffic flows within battlefield scenarios. We show how the protocol can be design to be traffic-aware and how this further improves the scalability of the routing overhead for tactical MANET scenarios.

Three MIBs: • DYMO-MIB <draft-ietf-manet-dymo-mib-02.txt> [1] • SMF-MIB <draft-ietf-mane... more Three MIBs: • DYMO-MIB <draft-ietf-manet-dymo-mib-02.txt> [1] • SMF-MIB <draft-ietf-manet-smf-mib-00.txt> [2]

This study presents an analysis of computer worm propagation in a Mobile Ad-hoc Network (MANET). ... more This study presents an analysis of computer worm propagation in a Mobile Ad-hoc Network (MANET). According to the recent DARPA BAA - Defense Against Cyber Attacks on MANETS (DARPA, 2004), "One of the most severe cyber threats is expected to be worms with arbitrary payload that can infect and satu- rate MANET-based networks on the order of seconds". Critical to

SPIE Proceedings, 2007

The Global Information Grid (GIG) is a collection of systems, programs and initiatives aimed at b... more The Global Information Grid (GIG) is a collection of systems, programs and initiatives aimed at building a secure network and set of information capabilities modeled after the Internet. The GIG is expected to facilitate DoD's transformation by allowing warfighters, policy makers, and support personnel to engage in rapid decision making. The roadmap is designed to take advantage of converged services of voice, data, video, and imagery over common data links. The vision is to have commanders identify threats more effectively, make informed decisions, and respond with greater precision and lethality. The information advantage gained through the GIG and network-centric warfare (NCW) allows a warfighting force to achieve dramatically improved information positions, in the form of common operational pictures that provide the basis for shared situational awareness and knowledge, and a resulting increase in combat power. The GIG Precedence and Preemption (P&P) requirements stem from the need to utilize scarce resources at critical times in the most effective way in support of national security, the intelligence community and the war-fighter. Information Assurance (IA) enables all information and data to be available end-to-end to support any mission without delay in accordance to the sensitivity of the task. Together, P&P and IA ensure data availability integrity, authentication, confidentiality, and non-repudiation. This study addresses and analyzes the QoS and P & P requirements and architecture for the GIG. Threat scenarios are presented and used to evaluate the reference architectures. The goal of the study is to assess the Information Assurance concerns associated with implementing Precedence and Preemption within the GIG and to guarantee an acceptable minimum level of security and protection for DoD networks.

MILCOM 2005 - 2005 IEEE Military Communications Conference

External Border Gateway Protocol (eBGP) is the ubiquitous protocol used today for advertisement o... more External Border Gateway Protocol (eBGP) is the ubiquitous protocol used today for advertisement of reachability information and for route selection among administrative domains (Autonomous Systems or ASs) in the Internet. However, many emerging needs in commercial and military networking have exposed limitations of the current eBGP. In particular, these IP networks of the future will carry a very diverse mix of applications, with very diverse Quality of Service (QoS) requirements (in the broad sense of the phrase). Some of these networks also have a very diverse set of component networks (wireless and wireline, fixed and mobile with different degrees of mobility, long lived and short term ad-hoc) and some of the component networks may be very dynamic in their service capabilities. These scenarios call for enhancing eBGP to allow for multi-topology and QoS-aware routing, using several QoS metrics in decision making. In such an enhanced BGP, more than one route (or path vector) may be propagated in BGP_UPDATE messages, helping optimize with respect to different QoS metrics as needed by different traffic types. In this paper, we discuss such an enhancement of eBGP. We develop details of advertisements, route thinning, and route selection needed to make the eBGP multi-topology and QoS-aware in the sense described above. We take the eBGP and internal BGP (iBGP) advertisement and route selection process and identify any modifications needed at each stage. We also discuss interactions between eBGP and iBGP and between BGP and the Interior (intra-domain) Gateway Protocol (IGP) needed to make the approach work end-to-end. We also discuss alternative ways to ensure that packets follow the selected end-to-end routes (both within and between domains). In particular, the potential uses of MPLS, source routing, tunneling, and DiffServ/ToS bits for this purpose are discussed in the paper.

Address-Identifier Mapping System for scalable routing

2009 IEEE Symposium on Computers and Communications, 2009

The main architectural problem with the current inter-domain routing model is the overloading of ... more The main architectural problem with the current inter-domain routing model is the overloading of IP addresses due to their use for identification, location, and forwarding. This makes it hard to support the need for multi-homing, traffic engineering, and mobility while maintaining address hierarchy that is essential for scalable routing. Thus, there is a need to separate identifiers from locators. In this paper we identify architectural and protocol changes in addressing and routing needed to provide major improvements in scalability. We design a corresponding protocol solution (Address-Identifier Mapping System-AIMS) based on separation of identification and addressing, and a mechanism for mapping ID to address.

Automated discovery of information services in heterogeneous distributed networks

MILCOM 2008 - 2008 IEEE Military Communications Conference, 2008

... Harshavardhana Applied Physics Laboratory Johns Hopkins University Laurel, MD, USA Abstract—T... more ... Harshavardhana Applied Physics Laboratory Johns Hopkins University Laurel, MD, USA Abstract—The Global Information Grid (GIG) will be com-prised of collections of different Service Capability Domains (SCDs). Each SCD offers a set of information services, such as Voice ...

ietf.org

Four MIBs related to MANET WG protocols:• DYMO MIB< ietf-manet-dymo-mib-02. txt>[1]• SMF MI... more Four MIBs related to MANET WG protocols:• DYMO MIB< ietf-manet-dymo-mib-02. txt>[1]• SMF MIB< ietf-cole-manet-smf-mib-02. txt>[2]• NHDP MIB< ietf-cole-manet-nhdp-mib-01. txt>[3]• OLSR MIB< ietf-cole-manet-olsr-mib-01. txt>[4]

Comparative performance of interleaved and non-interleaved pipelining in ATM terminal adapters

Computer Networks and ISDN Systems, 1995

In this paper we compare the end-to-end delay performance of two service disciplines that an Asyn... more In this paper we compare the end-to-end delay performance of two service disciplines that an Asynchronous Transfer Mode (ATM) multiplexor can use to multiplex pipelined synchronous native protocol frames arriving over low speed access lines onto higher speed ATM trunks. The ATM multiplexor must convert native protocol frames on the access lines (typically hundreds of bytes in length) into ATM cells on the trunks (of fixed length 53 bytes) at the network access and the corresponding ATM (de)multiplexor must reassemble these multiple ATM cells into a bit continuous synchronous native protocol frame at the network egress.In one service discipline, the multiplexor (hereafter referred to as a terminal adaptor, or TA) pipelines one synchronous frame at a time onto the high speed trunk, waiting, if it needs to, for the successive ATM cells from this one synchronous frame to accumulate. This scheme introduces a larger queueing delay at the ingress TA but no playout delay is required at the egress TA. In the other scheme the TA interleaves the ATM cells from the various synchronous frames arriving concurrently over the low speed lines. An interleaving scheme has a smaller queueing delay, but introduces a large variability in the network insertion times of the ATM cells corresponding to a native protocol frame. Hence the egress TA must enforce a delay before playing out the original bit-synchronous native frame over a low speed line, so as to increase the probability that the ATM cells are available when required to properly reassemble the native synchronous frame into a bit continuous stream.Using an analytical model for the first scheme and a simulation model for the second scheme we analyze the end-to-end delay of a synchronous frame, and compare the mean end-to-end delay for various trunk speeds (TA-to-network switch) to “access” line speed ratios. We conclude that, for the cases studied in this paper, if this ratio is greater than or equal to 4 then, over the range of useful loading, interleaved pipelining typically yields smaller mean delays than noninterleaved pipelining. If the ratio is less than 4 then interleaving typically yields larger mean delays for native protocols due to increased playout delays at the egress TA.

ACM SIGCOMM Computer Communication Review, 2001

We describe a method for monitoring Voice over IP (VoIP) applications based upon a reduction of t... more We describe a method for monitoring Voice over IP (VoIP) applications based upon a reduction of the ITU-T's E-Model to transport level, measurable quantities. In the process, 1) we identify the relevant transport level quantities, 2) we discuss the tradeoffs between placing the monitors within the VoIP gateways versus placement of the monitors within the transport path, and 3) we identify several areas where further work and consensus within the industry are required. We discover that the relevant transport level quantities are the delay, network packet loss and the decoder's de-jitter buffer packet loss. We find that an in-path monitor requires the definition of a reference de-jitter buffer implementation to estimate voice quality based upon observed transport measurements. Finally, we suggest that more studies are required, which evaluate the quality of various VoIP codecs in the presence of representative packet loss patterns.

This study presents an analysis of computer worm propagation in a Mobile Ad-hoc Network (MANET). ... more This study presents an analysis of computer worm propagation in a Mobile Ad-hoc Network (MANET). According to the recent DARPA BAA - Defense Against Cyber Attacks on MANETS (DARPA, 2004), ”One of the most severe cyber threats is expected to be worms with ...

MANET network management and performance monitoring for NHDP and OLSRv2

2010 International Conference on Network and Service Management, 2010

Proceedings of the 6th international workshop on Software and performance - WOSP '07, 2007

In this paper, we propose a new approach for mitigation of worm propagation through tactical Mobi... more In this paper, we propose a new approach for mitigation of worm propagation through tactical Mobile Ad-Hoc Networks (MANETs) which is based upon performance signatures and software rejuvenation. Three application performance signature and software rejuvenation algorithms are proposed and analyzed. These algorithms monitor critical applications' responsiveness and trigger actions for software rejuvenation when host resources degrade due to a coresident worm competing for host resources. We analyze the effectiveness of our algorithms through analytic modeling and detailed, extensive simulation studies. The key performance metrics investigated are application response time, mean time between rejuvenations and the steady state probability of host infection. We also use simulation models to investigate several design and parameter tuning issues. We investigate the relationship between the rate at which the application performance monitors can detect outof-specification applications and the rate of worm propagation in the network.

MILCOM 2005 - 2005 IEEE Military Communications Conference, 2005

We have embarked upon the development of a reusable Global Information Grid (DID) simulation plat... more We have embarked upon the development of a reusable Global Information Grid (DID) simulation platform in order to support GIG architecture, design and engineering. We followed a classical systems engineering approach to the design of the GIG simulation platform. We have identified a set of useful performance studies to perform related to GIG architecture and design. We present our approach to the design of our GIG simulation platform and the development of a GIG topology model allowing for automated simulation configurations. As an example of the platform's utility, we briefly discuss our initial studies of BGP performance in GIG-like environments. We conclude with a discussion of follow on work on our GIG simulation platform.

MILCOM 2007 - IEEE Military Communications Conference, 2007

In the Department of Defense's (DoD) Global Information Grid (GIG) transport network, packet hand... more In the Department of Defense's (DoD) Global Information Grid (GIG) transport network, packet handling must provide preferential transport to high Precedence traffic under all networking conditions, specifically conditions of resource scarcity, e.g., network overload conditions, while simultaneously satisfying packet scheduling required to meet application Quality of Service (QoS) needs. Our approach to this duality is to enhance Active Queue Management (AQM) techniques to provide Precedence and Preemption (P&P) capabilities and rely upon standard, well studied QoS Per Hop Behavior (PHB), e.g., Weighted Round Robin, Class-Based Fair Queuing, etc., for handling QoS requirements. In this way, when operating under engineered loads, the well known scheduling algorithms support high quality QoS for applications. Under network congestion situations, the enhanced AQM layer provides the necessary P&P preferential packet handling favoring high Precedence-Level (P-L) information. Our scheme allows low order queues (within the context of QoS handling) to plead up to the next higher order queue for help in alleviating queue congestion under periods of communication link overload. We refer to our scheme as the Cross Queue-AQM (CQ-ACM) Scheme. Our scheme can be extended to higher numbers of queues and any type of scheduler in a straightforward manner. Through extensive simulation studies and analytical modeling, we investigate the performance of our CQ-AQM scheme under heavy traffic limits, where Preemption is required. The performance metrics of interest to our analysis are packet delay, packet loss and throughput as a function of the packet QoS class and P&P level. Our previous studies concentrated on general nonflow controlled traffic and showed that our algorithms performed extremely well. In this paper we extend our analysis to flowcontrolled traffic by incorporating TCP traffic models into our simulation studies. We find that the application of our CQ-AQM scheme on top of standard QoS scheduling is effective in simultaneously supporting QoS and P&P transport for TCP flows as well.

2007 IEEE Pacific Rim Conference on Communications, Computers and Signal Processing, 2007

Routing in Mobile Ad-hoc Networks (MANETS) has proved to be an extremely challenging research pro... more Routing in Mobile Ad-hoc Networks (MANETS) has proved to be an extremely challenging research problem due to the high frequency of link changes in wireless mobile environments. Most known routing protocols struggle to maintain complex routing structures, e.g., N spanning trees, or use expensive (from the perspective of communications cost) methods for path discovery. These methods incur extreme communications costs in most MANET deployments. In this paper, we investigate the performance of a relatively unstudied class of routing protocols which we refer to as Beacon-Based Routing Protocols. This class of protocols maintain minimum routing structures and use these structures to boot strap path discovery. In a well defined sense, this class of routing protocols achieves optimal performance with respect to minimizing the communications costs associated with on-demand routing. We specifically investigate the impact of multiple tree implementations for path discovery and analyze their impact on the effectiveness of optimal path discovery.

Lecture Notes in Computer Science, 2006

We investigate the performance of of several protocol enhancements to the On-Demand Secure Byzant... more We investigate the performance of of several protocol enhancements to the On-Demand Secure Byzantine Routing (ODSBR) [3] protocol in the presence of various Byzantine Attack models. These enhancements include a) Nodal Weighting (in addition to Link Weighting) in the reputation database, b) a network layer retransmission capability and c) modifications to the packet flow rates. These enhancements are meant to improve the learning rate of the protocol in the presence of various Byzantine Attack models. The attack models investigated include previously investigated models [4] and a new and effective attack model, termed the MAC-Level Attack. We investigate the dynamics of the ODSBR protocol and its enhancements through analytic models and extensive simulation studies. We find that the protocol enhancements improve the learning times of the ODSBR protocol. The Nodal Weighting enhancement specifically helps in the presence of the various colluding Byzantine Attack models investigated. However, the time to develop a relatively complete reputation database in the MANET context is found to be relatively large.

MILCOM 2007 - IEEE Military Communications Conference, 2007

The U.S. Department of Defense's (DoD) warfighter is reliant upon the development of a reliable, ... more The U.S. Department of Defense's (DoD) warfighter is reliant upon the development of a reliable, resilient communications capability under harsh, battlefield environments. Due to high mobilities and the nature of the various terrains, the dynamics of the communications links is extremely erratic and rapidly changing. This results in extreme strain on the performance of routing protocols attempting to find and maintain viable communications paths. In this paper we discuss and analyze a new class of routing protocols which we refer to as Beacon-Based Routing protocols. Beacon-Based Routing protocols proactively build a small number of, typically one or two, spanning trees in the network and use these trees to discover paths on demand. The existence of one (or more) spanning tree(s) ensures full network connectivity and hence can be used to find network paths without the need for network-wide broadcast of discovery messages, as in other on-demand routing protocols. This class of routing protocols represents the generalization of the Pulse Protocol [1], originally developed in 2002 for applications to Internet access networks. The performance of the Pulse Protocol was analyzed in [1] and [2] in various applications including general Mobile Ad-Hoc Networks (MANETs) and in sensor networks. As we discuss in this paper, the Beacon-Based Routing protocol class has optimal behavior with respect to the communications overhead required to run the protocol. As such, its scaling behavior is superior to other existing routing protocol classes when assessed in the context of a MANET. Further, the performance of the protocol is discussed in the specific context of traffic flows within battlefield scenarios. We show how the protocol can be design to be traffic-aware and how this further improves the scalability of the routing overhead for tactical MANET scenarios.