published_or_final_version / Computer Science and Information Systems / Master / Master of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

This thesis work exhibits the survival of IPv4 addressing architecture and also about the distribution and allocation of IPv4 addresses. The fast growth of the Internet demands huge address space and it is the prominent cause for IPv4 exhaustion. The information regarding the existence of IPv4 addressing architecture in spite of its huge demand for the address space is also discussed. The temporary solutions like private IP addresses, CIDR, NAT makes the life of V4 still alive. But the permanent solution is to shift towards the new addressing scheme, IPv6. The merits and demerits of using both the addressing scheme are also discussed. Deploying IPv6 leads to the co-existence of V4 and V6 during the transition phase. Hence appropriate tunneling and transition techniques have to be deployed to make communication possible across both the addressing scheme. After the transition period the whole internet will be operating with V6 address. During that phase packet travelling across LAN will be carrying huge header to payload ratio. Hence finally this paper also brings out a suggestion on reducing this ratio across the local traffic in the V6 environment.

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The advent of high-speed networks may soon increase the network bandwidth available to workstation class computers by two orders of magnitude. Combined with the dramatic increase in microprocessor speed, these technological advances make possible new kinds of applications, such as multimedia and parallel computing on networks of workstations. At the same time, the operating system, in its role as mediator and multiplexor of computing resources, is threatening to become a bottleneck. The underlying cause is that main memory performance has not kept up with the growth of CPU and I/O speed, thus opening a bandwidth gap between CPU and main memory, while closing the old gap between main memory and I/O. Current operating systems fail to properly take into account the performance characteristics of the memory subsystem. The trend towards server-based operating systems exacerbates this problem, since a modular OS structure tends to increase pressure on the memory system. This dissertation is concerned with the I/O bottleneck in operating systems, with particular focus on high-speed networking. We start by identifying the causes of this bottleneck, which are rooted in a mismatch of operating system behavior with the performance characteristics of modern computer hardware. Then, traditional approaches to supporting I/O in operating systems are re-evaluated in light of current hardware performance tradeoffs. This re-evaluation gives rise to a set of novel techniques that eliminate the I/O bottleneck.

High level communication system design is of increasing interest as the interconnection of computer systems becomes more widespread. High level communication, systems provide users/applications with a convenient virtual communication environment that is an abstraction of the underlying transport communication mechanism. Examples include high level protocol support for file transfer, virtual terminal and mail delivery applications. We describe the implementation of communication software support for the ITI virtual terminal protocol using an existing X.25 protocol implementation. The design and implementation of a high level communication system using an experimental research computer system is described within this thesis. We also present a design that is a generalization of the model implemented and compare this with other communication models, notably the ISO Open Systems Interconnection model and the Xerox Pup internetwork architecture. In particular we address the following issues: (a) Dynamic protocol layer initiation from an incoming call. (b) Utilization of a uniform interface between protocol layers and at the user interface. Within the implementation described this is achieved using an interprocess message based I/O protocol. (c) The suspension of higher layers and application processes after a transport level failure and the subsequent reconnection when the transport connection is re-established. The design utilizes layered communication modules that provide external (high level) protocol support or alternatively may provide local services and functions such as local data transformation and reconnection functions. The utilization of a uniform interface between modules and at the user interface allows the liberal interconnection of modules to provide the required communication services with a minimum of overhead. / Science, Faculty of / Computer Science, Department of / Graduate

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