Institute for Systems Research

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Author: search.filters.author.Karir, Manish

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    IPSEC and the Internet
    (1999) Karir, Manish; Baras, John S.; ISR; CSHCN
    Secure and efficient communication between computers is becoming more essential as companies attempt to utilize the public network infrastructure for supporting communication between their various sites.

    The IPSEC protocols have been proposed as a solution to balance the needs of security and networking between computers. The basic IPSEC protocols are based on the end-to-end security model and when used in the most secure mode do not allow any intermediate nodes in the network to access and obtain information from packet headers encrypted by the security end-points.

    However, with the advent of smart applications in the middle of the network, which attempt to make it more efficient, a tradeoff is created between security and efficiency. This tradeoff is the result of the need for these intelligent applications to access packet header information which is not possible with secure IPSEC flows.

    This thesis analyzes and evaluates several possible solutions to this problem and argues why they all involve an unacceptable loss in the level of security or are not practical in any real system. On the basis of these arguments it thenproposes the use of Layered IPSEC to solve the problem. Layered IPSEC adds flexibility to the current IPSEC protocols by providing the ability to use multiple encryption algorithms with separate encryption keys for different parts of a packet.

    We also describe an experimental implementation of the concept and provide timing measurements from it. On the basis of our experience with the implementation and our experimental measurements we argue for the feasiblity and usefulness of this scheme.

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    A Simulation Study of Enhanced TCP/IP Gateways for Broadband Internet over Satellite
    (1999) Karir, Manish; Liu, Mingyan D.; Barrett, Bradley A.; Baras, John S.; Baras, John S.; ISR; CSHCN
    The demand for Internet bandwidth has been growing rapidlyover the years and the use of high-bandwidth satellites has been proposed as one possible solution to meet the increasingdemand.

    However, there are certain performance problems withproviding Internet over satellite due to the nature of TCP/IP protocol suite and the satellite link characteristics. In this paper, we describe a simulation study of an architecture for improving the performance of TCP/IP over satellite links.

    On each end of the satellite link, there are gateways that split the TCP connection so that the satellite link is transparent to the end hosts.

    The split TCP connection over the satellite segment is then optimized.TCP congestion control is maintained on each segment of the split connection.

    We simulated such an architecture in OPNET and present results showing improved throughput over the satellite link.

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    Caching and Multicasting in DBS Systems
    (1999) Liu, Mingyan D.; Karir, Manish; Baras, John S.; Baras, John S.; ISR; CSHCN
    The use of Caching and Multicasting has been studied extensively inthe context of terrestrial networks. However, the use of thesetechnologies in a Direct Broadcast Satellite(DBS) system remains unclear.In this paper we discuss possible choices of caching and multicasting schemes, motivated by current applications in the terrestrial Internet,that could be considered for a DBS system. We examine their advantages and disadvantages as well as the tradeoffs involved in combinations of different approaches. We also propose some uses of these technologies and describe an architecture that enhances the performance and efficiency of a DBS system. This paper is published in the Proceedings of International Workshop on Group Communication, International Conference on Parallel Processing, September 1999.
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    Hybrid Internet Simulation Testbed
    (1999) Liu, Mingyan D.; Karir, Manish; Raissi-Dehkordi, Majid; Baras, John S.; Baras, John S.; ISR; CSHCN
    Internet technology as a widely accepted modern telecommunicationstandard has been widely extended to combine with numerous othertechnologies, e.g., satellite, ATM, wireless. This is whatwe term Hybrid Internet. Along with this technology emerging,various enhancements and alterations of standard TCP/IP for differentpurposes have been proposed and studied intensively. More and morefrequently we are facing the question of how to choose from thesedifferent schemes to design a system for a particular purpose, whichwould inevitably involve the interaction and trade-off study. We believethat simulation is a powerful tool for this type of work.In this paper, we describeour implementation of a Hybrid Internet testbed which includesa series of traffic models and TCP/IP enhancements.The goal of our work is to makea set of reusable modules upon which we can build complex systemsto study the standard protocols and their variations.We also present application examples using these module components.
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    Extensions of DBS and Hybrid Internet
    (1997) Karir, Manish; Bharadwaj, Vijay G.; Holleman, Keith; Suphasindhu, Narin; Papademetriou, Spyro; Baras, John S.; ISR; CSHCN
    There has been a large amount of research dedicated to extending the asymmetric networks provided by receive-only Direct Broadcast Satellite systems like Hughes Network Systems' DirecPC product. One way to further develop Direct Broadcast Satellite services and to offset the high initial cost of these systems is to implement techniques that will allow one satellite receiver to act as a gateway for many clients to receive information. This would also help broaden the range of services provided by DBS systems. Besides providing direct-to-home traffic, DBS can be used to distribute bulk traffic to the local-loop distributors (direct-to-curb). We describe some experiments which extend the DBS system, in particular, the DirecPC and DirecTV DBS, by using the PC with the satellite receiver as a gateway to connect networks together. We also discuss simple methods of receiving multimedia traffic from the multicast backbone (MBONE) [Cas94] over the satellite link, and distributing it, through this gateway, to end users.

    The research and scientific content in this material will be presented at the 2nd ACM International Workshop on Satellite-Based Information Services (WOSBIS), October 1, 1997, Budapest, Hungary.
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    Integrated Product and Process Design Environment Tool for Manufacturing T/R Modules
    (1997) Karne, Ramesh K.; Lai, Hsing-Tsu; Dandekar, Swati V.; Baras, John S.; Ball, Michael O.; Bashyam, Sridhar; Trichur, Vinai S.; Karir, Manish; Kebede, Abraham; Williams, Jim; ISR; CSHCN
    We present a decision making assistant tool for integrated product and process design environment for manufacturing applications. Specifically, we target microwave modules which use Electro-mechanical components and require optimal solutions to reduce cost, improve quality, and gain leverage in time to market the product. This tool will assist the product and process designer to improve their productivity and also enable to cooperate and coordinate their designs through a common design interface. We consider a multiobjective optimization model that determines components and processes for a given conceptual designs for microwave modules. This model outputs a set of solutions that are Pareto optimal with respect to cost, quality, and other metrics. In addition, we identify system integration issues for manufacturing applications, and propose an architecture which will serve as a building block to our continuing research in virtual manufacturing applications.