1,855 research outputs found
Active congestion control using ABCD (available bandwidth-based congestion detection).
With the growth of the Internet, the problem of congestion has attained the distinction of being a perennial problem. The Internet community has been trying several approaches for improved congestion control techniques. The end-to-end approach is considered to be the most robust one and it has served quite well until recently, when researchers started to explore the information available at the intermediate node level. This approach triggered a new field called Active Networks where intermediate nodes have a much larger role to play than that of the naive nodes. This thesis proposes an active congestion control (ACC) scheme based on Available Bandwidth-based Congestion Detection (ABCD), which regulates the traffic according to network conditions. Dynamic changes in the available bandwidth can trigger re-negotiation of flow rate. We have introduced packet size adjustment at the intermediate router in addition to rate control at sender node, scaled according to the available bandwidth, which is estimated using three packet probes. To verify the improved scheme, we have extended Ted Faber\u27s ACC work in NS-2 simulator. With this simulator we verify ACC-ABCD\u27s gains such as a marginal improvement in average TCP throughput at each endpoint, fewer packet drops and improved fairness index. Our tests on NS-2 prove that the ACC-ABCD technique yields better results as compared to TCP congestion control with or without the cross traffic. Source: Masters Abstracts International, Volume: 43-03, page: 0870. Adviser: A. K. Aggarwal. Thesis (M.Sc.)--University of Windsor (Canada), 2004
RAPTOR: Routing Attacks on Privacy in Tor
The Tor network is a widely used system for anonymous communication. However,
Tor is known to be vulnerable to attackers who can observe traffic at both ends
of the communication path. In this paper, we show that prior attacks are just
the tip of the iceberg. We present a suite of new attacks, called Raptor, that
can be launched by Autonomous Systems (ASes) to compromise user anonymity.
First, AS-level adversaries can exploit the asymmetric nature of Internet
routing to increase the chance of observing at least one direction of user
traffic at both ends of the communication. Second, AS-level adversaries can
exploit natural churn in Internet routing to lie on the BGP paths for more
users over time. Third, strategic adversaries can manipulate Internet routing
via BGP hijacks (to discover the users using specific Tor guard nodes) and
interceptions (to perform traffic analysis). We demonstrate the feasibility of
Raptor attacks by analyzing historical BGP data and Traceroute data as well as
performing real-world attacks on the live Tor network, while ensuring that we
do not harm real users. In addition, we outline the design of two monitoring
frameworks to counter these attacks: BGP monitoring to detect control-plane
attacks, and Traceroute monitoring to detect data-plane anomalies. Overall, our
work motivates the design of anonymity systems that are aware of the dynamics
of Internet routing
Link State Contract Routing
The Internet's simple design resulted in huge success in basic telecommunicationservices. However, the current Internet architecture has failed in terms of introducingmany innovative technologies as end-to-end (E2E) services such as multicasting,guaranteed quality of services (QoS) and many others. We argue that contractingover static service level agreements (SLA) and point-to-anywhere service definitionsare the main reasons behind this failure. In that sense, the Internet architecture needsmajor shifts since it neither allows (i) users to indicate their value choices at sufficientgranularity nor (ii) providers to manage risks involved in investment for new innovativeQoS technologies and business relationships with other providers as well as users.To allow these much needed economic flexibilities, we introduce contract-switching asa new paradigm for the design of future Internet architecture. In this work, we implementcontract-routing framework with specific focus on long-term contracted servicesin Link State Contract Routing scheme. Our work shows that E2e guaranteed QoSservices can be achieved in routing over contracted edge-to-edge service abstractionswhich are built on today's popular protocols with reasonable protocol overhead
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