Douglas C. Montgomery

A Reliable Message Delivery Protocol for Mobile Agents

The abstractions and protocol mechanisms that form the basis for inter-agent communications can significantly impact the overall design and effectiveness of Mobile Agent systems. We present the design and performance analysis of a reliable communication mechanism for Mobile Agent systems. Our protocols are presented in the context of a Mobile Agent system called AGNI . We have developed AGNI communication mechanisms that offer reliable peer-to-peer communications, and that are integrated with our agent location tracking infrastructure to enable efficient, failure-resistant networking among highly mobile systems. We have analyzed the design parameters of our protocols using an in-situ simulation approach with validation through measurement of our prototype implementation in real distributed systems. Our system assumptions are simple and general enough to make our results applicable to other Agent systems that may adopt our protocols and/or design principles.

Mobile Streams: a middleware for reconfigurable distributed scripting

A large class of distributed applications follow an event-driven or reactive paradigm. Such applications can benefit from mobile agent technology by making it easy to add reconfigurability, extensibility and failure resilience features at an application level. We present the design of middleware for building reactive, extensible, reconfigurable distributed systems, based upon an abstraction which we call Mobile Streams. Using our system, a distributed, event-driven application can be scripted from a single point of control and dynamically extended and reconfigured while it is executing. Our system is suitable for building a wide variety of applications; for example, distributed testing, conferencing and control-oriented applications. We illustrate the use of our system by presenting example applications.

Design and analysis of optimization algorithms to minimize cryptographic processing in BGP security protocols

The Internet is subject to attacks due to vulnerabilities in its routing protocols. One proposed approach to attain greater security is to cryptographically protect network reachability announcements exchanged between Border Gateway Protocol (BGP) routers. This study proposes and evaluates the performance and efficiency of various optimization algorithms for validation of digitally signed BGP updates. In particular, this investigation focuses on the BGPSEC (BGP with SECurity extensions) protocol, currently under consideration for standardization in the Internet Engineering Task Force. We analyze three basic BGPSEC update processing algorithms: Unoptimized, Cache Common Segments (CCS) optimization, and Best Path Only (BPO) optimization. We further propose and study cache management schemes to be used in conjunction with the CCS and BPO algorithms. The performance metrics used in the analyses are: (1) routing table convergence time after BGPSEC peering reset or router reboot events and (2) peak-second signature verification workload. Both analytical modeling and detailed trace-driven simulation were performed. Results show that the BPO algorithm is 330% to 628% faster than the unoptimized algorithm for routing table convergence in a typical Internet core-facing provider edge router.