Center for Satellite and Hybrid Communication Networks
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Papers resulting from CSHCN-related research are periodically added to the Institute for Systems Research Technical Report Database where they can be browsed by year or searched by author or keywords.


On QoS Provisioning in ATM Networks (CSHCN TR 2002-7) by Anubhav Arora, John S. Baras

ATM is representative of the connection-oriented resource provisioning class of protocols. An ATM network is expected to provide end-to-end QoS guarantees to connections in the form of bounds on delays, errors and/or losses. Performance management involves measurement of QoS parameters, and application of control measures (if required) to improve the QoS provided to connections, or to improve the resource utilization at switches. QoS provisioning is very important for real-time connections in which losses are irrecoverable and delays cause interruptions in service. Most scheduling disciplines provide static allocation of resources at connection setup time. End-to-end bounds are obtainable for some schedulers, however these are precluded for heterogeneously composed networks. The resource allocation does not adapt to the QoS provided to connections in real-time. In addition, mechanisms to measure the QoS of a connection in real-time are scarce.

A novel framework for QoS management is proposed in this paper to provide QoS guarantees to real-time connections. It comprises of in-service QoS monitoring mechanisms, a hierarchical scheduling algorithm based on dynamic priorities that are adaptive to measurements, and methods to tune the schedulers at individual nodes based on the endto- end measurements.

[ATIRP QK9931]


Authenticated Key Agreement in Dynamic Groups (CSHCN TR 2002-1) by Arvind Mani

Multicast security poses interesting challenges in the area of key management. Designing a good protocol for key agreement in dynamic multicast groups involves a thorough understanding of the trade-offs that exist among storage, communication and computation overhead. The contribution of this thesis is a verifiable protocol for authenticated key agreement based on a distributed key generation scheme. The underlying key generation scheme has shown promise in being natural for collaborative group applications. The protocol can then be tailored to particular applications once we understand the communication, storage and computation constraints specific to the application. To handle group membership changes in dynamic groups, an auxiliary key agreement protocol is introduced. The auxiliary protocol re-uses contributions to the key in the previous round, to form the new key. The key shares of the members contributing fresh values in the current round are more susceptible to discovery by colluding group members (not outsiders). The auxiliary protocol does not introduce any other security weakness. A protocol that starts from the scratch on membership change is going to be expensive, slow and unsuitable for most applications. We use the well-known Logical Key Tree (LKH) structure to allow the key management (distribution) part of the protocol to scale to large groups. The key tree structure helps to localize the effect of membership change and as a result, reduces the communication overhead to form the new session key.

[ATIRP QK9931 & NASA NCC3528]


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