CSCE990: Networks Systems Seminar

Spring 2000

Instructors: 

Prof. Byrav Ramamurthy (byrav@cse.unl.edu)

Prof. Steve Goddard (goddard@cse.unl.edu)

Meets: 11.00 Am - 12.00Pm on Tuesdays.

  • Security in the World Wide Web: Secure Socket Layer(SSL).
  • Packet-switched optical networks: switching schemes and performance analysis.
  • Lightpath establishment and management in High Bandwidth Optical WAN's.
  • Integration Strategies for IP over WDM.
  • Connection Management for Wavelength-Routed WDM Networks.
  • Network Authentication - "Kerberos" .
  • Denial of Service attacks.
  • Modeling and simulating Communication Networks using OPNET. Modeling and simulating High Speed Networks.
  • Routing in Wireless Ad Hoc Networks.
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    Title: Security in the World Wide Web: Secure Socket Layer(SSL).
    Speaker: Kavitha Subramani (kavitha@cse.unl.edu)
    Venue: 114 Ferguson
    Time: 11am, Tuesday, Feb. 1, 2000
    Abstract: These days the web is basically a Free-For-All service. The number of individuals and companies with Internet access is increasing rapidly. All businesses, most government agencies and many individuals have web sites of their own. But the reality is that the Internet and the web are extremely vulnerable to compromises of various sites. The identity of the client is not known. The identity of the server is not proven. As a result Client anonymity, eavesdropping became easy. As businesses wake up to this reality, the demand for secure web services grows. This topic of web security begins with a discussion of some of the web security threats along with the design and working of one of the most prominent web security system called SSL (Secure Sockets Layer). In this talk we will discuss record protocols and handshake protocols. We will also briefly discuss the client authentication system used by the Netscape server.
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    Title: Packet-switched optical networks: switching schemes and performance analysis.
    Speaker: Ashok Ramakrishnan (aramakri@cse.unl.edu)
    Venue: 114 Ferguson
    Time: 11.00 Am , 8th Feb 2000.
    Abstract: In general, packet optical networks can be divided in to two categories: synchronous (slotted) and asynchronous (unslotted) networks. In a synchronous network fixed-length packets are alligned togeather before they enter a switch node. In asynchronous networks, the packets are not alligned, and can be of variable length. This talk will concentrate on an introduction to packet-switched optical networks, the switching schemes presently used, and a preliminary performance analyis. The discussion on synchronous networks will be based on simulation of a packet-switched optical network using staggering switches. --------------------------------------------------------------------------------------------------------------------------------------------------------
    Title: Lightpath establishment and management in High Bandwidth Optical WAN's
    Speaker: Ling Zhong
    Venue: 114 Ferguson
    Time: 11.00 Am , 22th Feb 2000.
    Abstract:
    "lightpaths", the optical transmission paths in the optical network, provides an approach to make use of emerging transmission and switching capabilities in the photonic domain and efficiently use the high bandwidth available provided by WDM. The performance of "lightpath" hinges on their efficient establishment and management. Although the problem of optically establishing lighpath is NP-complete, simple heuristics provide near optical solution. Here both static and dynamic lighpath establishment for bounded and unbounded number of wavelength were presented and evaluated.
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    Title: Integration Strategies for IP over WDM
    Speaker: Elie Sawma
    Venue: 114 Ferg. Hall.
    Time: 11.00 Am, 29th February.
    Integration Strategies for IP over WDM by Nasir Ghani
    Abstract: As advances in later two/three and optical networking technologies emerge, IP internetworking over WDM is becoming increasingly important. Much of the current work in this area has essentially focused on defining a lower (access) protocol layer for WDM networks to provide "circuit-switched" services to multiple higher-layer protocols (IP, ATM, and even SONET/SDH), i.e., optical-layering approach. This layer will perform channel routing, maintenance, and likely even restoration/protection tasks. For efficient integration with the IP-layer, however, important considerations still remain, i.e., traffic/resource engineering, failure recovery co-ordination, etc. Moreover, some may argue that this approach introduces yet another layer, posing increased operations costs. As optical networking devices improve and become more commonly available, closer interworkings will be desirable. Therefore a more direct, IP standards-based approach is proposed, termed "lambda-labeling", which extends the MPLS label-switching concepts to include wavelength-switched lightpaths. Optical nodes are treated as IP MPLS devices and label stacking is used at the edge of optical subnetworks to aggregate smaller LSP's from regular MPLS nodes into larger (discrete) "lambda" LSP entities associated with lightpaths. By using the MPLS explicit-routing and LSP restoration capabilities, a large body of work already done in the optical arena can be subsumed.
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    Title: Connection Management for Wavelength-Routed WDM Networks
    Speaker: Sree Rama Nomula (nomula@cse.unl.edu)
    Venue: 114 Ferguson
    Time: 11am, Tuesday
    Abstract:
    WDM has been rapidly gaining acceptance as a means to handle the ever-increasing bandwidth demands of network users. It is an approach that can exploit the huge opto-electronic bandwidth mismatch by requiring that each end-user equipment operate only at electronic rate, but multiple WDM channels from different end users may be multiplexed on the same fiber. For the wavelength routed WDM networks, a control mechanism is required to setup and takedown all-optical connections. The mechanism must be able to provide updates to reflect which wavelengths are currently being used on each link so that nodes may be informed about the routing decisions. An attempt is made to compare different distributed control mechanisms for establishing all-optical connections in a wavelegth routed WDM networks.
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    Title : Network Authentication - "Kerberos"
    Speaker : Parwez Pasha
    Venue : Ferguson Hall Rm 114
    Time : 11 AM
    Abstract: Many of the protocols used in the Internet do not provide any security. Tools to "sniff" passwords off of the network are in common use by systems crackers. Thus, applications which send an unencrypted password over the network are extremely vulnerable. Worse yet, other client/server applications rely on the client program to be "honest" about the identity of the user who is using it. Other applications rely on the client to restrict its activities to those which it is allowed to do, with no other enforcement by the server. Kerberos was created by MIT as a solution to these network security problems. The Kerberos protocol uses strong cryptography so that a client can prove its identity to a server (and vice versa) across an insecure network connection. After a client and server has used Kerberos to prove their identity, they can also encrypt all of their communications to assure privacy and data integrity as they go about their business.
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    Title: Denial of Service attacks
    Speaker: Mir Hussain Ali (mhali@cse.unl.edu)
    Venue: 114 Ferguson
    Time: 11.00 Am , 21th Mar 2000.
    ABSTRACT: Denial Of Service attacks "The Internet is very much an environment where networks and computers participate by playing by rules.It just takes somebody breaking those rules to cause problems" -- Gene Shklar, Keynote Systems. Denial of service attacks, in which a host bombards another system with large number of packets in an attempt to overwhelm legitimate traffic, aren't new. But the distributed denial-of-service attack uses an array of compromised systems to launch a distributed flood attack against a single target. Unlike attacks directed from one host, distributed attacks are more difficult to trace and can direct a larger volley of packets. Leading sites on the Web such as yahoo, ebay and others have been brought to their knees by distributed denial-of-service attacks. Such attacks flood a Web server with false requests for information, overwhelming the system and ultimately crashing it. This seminar gives an insight into how these attacks work and discusses how these can be dealt with, to the extent possible.
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    Topic : Modeling and simulating Communication Networks using OPNET. Modeling and simulating High Speed Networks.
    Speaker: Vijay Eadala
    Venue : 114 Ferguson
    Time : 11.00 Am
    OPtimized Network Engineering Tools (OPNET) is a comprehensive engineering system capable of simulating large communications networks with detailed protocol modeling and performance analysis. OPNET supports modeling efforts with a system of interrelated programs, model libraries, and data files. The primary tool of this system is the opnet program. The key features include object orientation, graphical specification, automated model creation, an extensive model suite, integrated analysis tools, and animation support. An example network model is used to demonstrate the opnet program and building methods. The second part of the presentation is the paper that discusses modeling and simulation of ultra high speed information transfer. Two candidate architectures are proposed in this paper and also discusses the service survivability with a restoration strategy proposed in this paper. The results are based on modeling and simulation techniques using OPNET.
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    Topic : Routing in Wireless Ad Hoc Networks.
    Speaker: Xukai Zou
    Time : 11.00 Am, 4 April 2000
    Wireless ad hoc networks are mobile distributed multihop wireless networks. In a wireless ad hoc network, there is no predetermined topology (preexisting fixed infrastructure) and no central control. The nodes in ad hoc networks communicate without wired connections among themselves by creating a network "on the fly". Wireless ad hoc networks are becoming more and more popular because of their easy deployment in many traditional applications, such as battlefield communications, law enforcement, disaster recovery (fire, earthquake), and emergency search and rescur, as well as in recently emerging civilian applications such as electronic classrooms, convention centers, construction sites, and special events (concerts, festivals).
    As in a wired network, routing (and forwarding) is a core problem in wireless ad hoc networks for delivering the traffic from one node to other nodes in networks. However because of the scarce bandwidth and highly dynamic topology in wireless ad hoc networks, routing protocols used in wired networks are not suitable for wireless ad hoc networks. Many routing protocols for wireless ad hoc networks have been proposed such as
    ABR (Associativity Based Routing),
    AODV (Ad hoc On-Demand Distance Vector routing),
    CEDAR (Core-Extraction Distributed Ad hoc Routing Algorithm),
    DSDV (Destination-Sequence Distance Vector),
    DSR (Dynamic Source Routing),
    FSR (Fisheye State Routing),
    GSR (Global State Routing),
    TORA (Temporally-Ordered Routing Algorithm),
    ZRP (Zone Routing Protocol)
    In this talk, we will breifly present the limitations and features of wireless ad hoc networks and classifications of routing protocols and discuss TORA protocol in more detail bacause of its ability to react fast on link failure and network partition.
    Reference:
    V. D. Park and M. S. Corson. A highly adaptive distributed routing algorithm for mobile wireless networks. Proceedings of INFOCOM '97, 3:1405--1413, April 1997.