CSCE 990 Networks Systems Seminar

Optimization of Protection Structure in Multicast Networks mainly focuses on path rerouting algorithm. Path rerouting is an algorithm, which creates redundant trees on arbitrary link-redundant networks. These trees are such that the destination is connected to the source by at least one of the trees in case of link failure. In case of failure, which leaves the node disconnected from the primary route, a backup route is used. Here the backup route doesn't share links with the primary route. The algorithm provides rapid preplanned recovery of communications with great flexibility in the topology design. Some experimental results show that path rerouting algorithm really works better in Multicast networks when the network is not reliable.

An increasing number of end-systems are being connected to the global communication infrastructure over relatively low-speed links. Especially an increasing number of first and last hops in the networks use wireless technology with limited bandwidth and relatively high-bit error rates. But the users always demand the same quality of service as they already have, using stationary computers attached to the wired network. To make things even worse, with the introduction of IPv6, which supports Mobility referred as Mobile IP, the basic header size increase from 40bytes[TCP/IPv4] to 100 bytes approximately. so when the bandwidth is a limited constraint it would be an inefficient approach to use a significant amount of bandwidth for just the protocol headers. So taking advantage of the fact that, most of the fields in these headers are the same for a flow, and that some fields can be inferred from the previous values, we would be discussing the header compression techniques, proposed by Mikael Degermark et al. Optimization of Protection Structure in Multicast Networks mainly focuses on path rerouting algorithm. Path rerouting is an algorithm, which creates redundant trees on arbitrary link-redundant networks. These trees are such that the destination is connected to the source by at least one of the trees in case of link failure. In case of failure, which leaves the node disconnected from the primary route, a backup route is used. Here the backup route doesn't share links with the primary route. The algorithm provides rapid preplanned recovery of communications with great flexibility in the topology design. Some experimental results show that path rerouting algorithm really works better in Multicast networks when the network is not reliable.

Abstract: Information flow has become more volatile due to the changing nature of business associations and by the emergence of new sources of available information. The Extensible Markup Language (XML) is one of the highly developing information representation methods on the Internet. It allows easy exchange of information in many different forms without the need to change the original document. This is done using content-based routing techniques. Currently XML documents are exchanged through the Internet over http, which reduces the potential benefits of the XML document. An XML broker is a middle-ware system that actually allows the client and server to truly exchange XML documents in their original format and be able to route the documents to their intended destination and in the correct format. The broker accepts documents from a client using http then determines, using some given rules, where to send this document and in what format. A couple of products are now in the market providing these facilities: 1. X-Bridge from Software AG 2. BizTalk from Microsoft They both offer somehow similar functionality, but with different methodology and tools. BizTalk works as a server and offers a broad range of tools for enterprise application integration, business to business integration and BizTalk orchestration technologies to allow building dynamic business processes. The X-Bridge is a middle-ware that runs with the application server. It is more focused and provides excellent tools and facilities for XML document exchange.

Abstract: With the advent and mass utilization of computers and networks in today's business world, network security has become a very large and important topic of discussion. Whether it is firewalls to keep people out of your network, cryptography to scramble important data or user education to minimize the risk of an accidental security breach, security takes many forms. This presentation will cover some of the important aspects of network security and highlight some of the unseen problems that affect nearly all businesses.

Abstract: In Optical networks, distributed control protocols are provided for setting up and taking down of connections reliably. These protocols allow connection originators to obtain resources with high probability by minimizing reservation conflicts, allow connections to stay up even if controllers along the network fail, ensure that all the resources taken up by a connection are released once the connection is taken down. Fast protocols are also proposed for handling link failures and wavelength failures on a link. These protocols are general in that they can be used in networks with different kinds of node architectures, different route computation algorithms that reflect the underlying constraints imposed by the nodes and the physical layer and any kind of underlying mechanism using which the network controllers can communicate with each other.

Abstract: Understanding web traffic characteristics is a key to improving the performance and scalability of the web. In this article web proxy workloads from different levels of a caching hierarchy are used to understand how the workload characteristics change across different levels of a caching hierarchy. The main observations of this study are that html and image documents account for 95% of the documents seen in the workload. The distribution of transfer sizes of documents is heavy tailed. Popularity does not necessarily Follow zipf distribution. One timers account for approximately 70 % of documents referenced.

Abstract: Computer system designers often use caches to solve performance problems. Caching in the World Wide Web also solves some problems related to bandwidth requirements and latency (as seen by the user). Traditionally web caches store responses to http requests in anticipation of a subsequent reference to a URL of a cached response. But numerous studies of actual web reference streams report hit rates less than 50% for web caches. These results urge for more sophisticated caching models to achieve high hit rates for web caches. This paper surveys a number of techniques for better exploiting the bits in HTTP caches and compares these techniques based on the following five metrics: latency, bandwidth requirements,cache coherency, CPU time, and proxy RAM requirements.

Abstract: The widespread use of the world wide web(WWB) and related applications places interesting performance demands on networks servers. The ability to measure the effect of these demands is important for tuning and optimizing the various software components that make up a Web server. To measure these effects, it is necessary to generate realistic HTTp client requests. Unfortunately, accurate generationof such traffic in a testbed of limited scope is not trivial. In particular, the commonly used approach is unable to generate client request-rates that exceed the capacity of the server being tested even for short periods of time. This paper examines pitfalls that one encounters when measuring Web server capacity using a synthetic workload. This paper discusses a new method proposed and evaluated for Web traffic generation that can generate bursty traffic, with peak loads that exceed the capacity of the server. Finally, the proposed method is used to measure the performance of a Web server.

Abstract: The paper presents a protocol WATCHERS that detects and reacts to routers that drop or misroute packets. The WATCHERS algorithm is run on each participating router in an autonomous system consisting of a set of routers and networks controlled by one administrative authority. WATCHERS can detect routers that selectively drop or misroute packets, as well as routers that cooperate to conceal malicious behaviour. It can identify the exact router(s) rather than a list of potential suspects. In ideal conditions it is argued that WATCHERS never makes a false-positive diagnosis and its impact on router performance and memory requirements are reasonable for many environments.

Abstract: Clusters of commodity-priced computers running the LINUX operating system are commonly referred to as Beowulfs. A survey of the Top 500 fastest machines in the world now includes a growing number of these machines. Drs. Jiang (CSE) and Swanson (IS and CSE) have recently received an $85,000 grant from the University Foundation to build the first Beowulf cluster for campus-wide research use at UNL. A prototype system of 8 high-end dual processor PCs has been ordered and will be tested this semester, while the bulk of the grant will be spent next semester on an additional 40-50 PCs and advanced networking hardware. Drs. Jiang and Swanson are co-teaching a course in CSE this semester that consists of hands-on development of both the prototype cluster and a cluster of PCs that is named Scavenger. This SCAlable Varied ENvironment for Graduate Education and Research, which presently consists of 16 Pentium class machines, was built with hardware that was recovered from University inventory for free. This informal talk will recount our experiences so far, touching on various issues, many of which remain to be researched and resolved.

Abstract:
The Internship was for a period of 11 weeks, starting from June 5 to Aug 18. During the Internship I underwent orientation and training. And I was assigned to these projects preparing "Documentation for Server Administration Work Bench (SAW) CUM3", "Server Monitoring" program coded in C. "Server Monitoring" program coded in Java. Java servlets for querying both Web Server and Enterprise Servers. Server Monitoring J.D.Edwards had different batches of One World running on different ports, different operating systems and different types of servers. This meant that a several ports on several servers had to be monitored continuously and effectively. The products objective was to monitor both Enterprise Servers and Web Servers, provide a web based approach so that the status could be verified from multiple locations and by multiple people, run continuously for an indefinite period of time, servers and ports and the programs setting could be changed on the fly. The programs should not be halted to change the configuration parameters. Logs of the server status should be available for the previous day. The programs also had to be cross platform.

Abstract:
In the last three years, the networking revolution has finally come of age. More than ever before, we see that the internet is changing computing as we know it. the possibilities and oppurtunities are limitless. Unforunately, so too are the riska and chances of malicious intrusions. It is very important that the security mechanisms of a system are designed so as to prevent unauthorized access to system resources and data. The field of research is called Intrusion Detection. Intrusion detection is still a fledging field of research. However, it is begining to assume enormous importance in today's computing environment.

Abstract:
Distributed object computing extends an object-oriented programming system by allowing objects to be distributed across a heterogeneous network, so that each of these distributed object components interoperate as a unified whole. These objects may be distributed on different computers throughout the network. Traditionally, two methods of object distribution have been available, CORBA and DCOM. Now a new protocol, SOAP has appeared on the horizon, bringing with it the ability to easily extend distributed objects to the Internet world, an ability that is sorely lacking in CORBA and DCOM.