674 research outputs found
In-packet Bloom filters: Design and networking applications
The Bloom filter (BF) is a well-known space-efficient data structure that
answers set membership queries with some probability of false positives. In an
attempt to solve many of the limitations of current inter-networking
architectures, some recent proposals rely on including small BFs in packet
headers for routing, security, accountability or other purposes that move
application states into the packets themselves. In this paper, we consider the
design of such in-packet Bloom filters (iBF). Our main contributions are
exploring the design space and the evaluation of a series of extensions (1) to
increase the practicality and performance of iBFs, (2) to enable
false-negative-free element deletion, and (3) to provide security enhancements.
In addition to the theoretical estimates, extensive simulations of the multiple
design parameters and implementation alternatives validate the usefulness of
the extensions, providing for enhanced and novel iBF networking applications.Comment: 15 pages, 11 figures, preprint submitted to Elsevier COMNET Journa
HT-Paxos: High Throughput State-Machine Replication Protocol for Large Clustered Data Centers
Paxos is a prominent theory of state machine replication. Recent data
intensive Systems those implement state machine replication generally require
high throughput. Earlier versions of Paxos as few of them are classical Paxos,
fast Paxos and generalized Paxos have a major focus on fault tolerance and
latency but lacking in terms of throughput and scalability. A major reason for
this is the heavyweight leader. Through offloading the leader, we can further
increase throughput of the system. Ring Paxos, Multi Ring Paxos and S-Paxos are
few prominent attempts in this direction for clustered data centers. In this
paper, we are proposing HT-Paxos, a variant of Paxos that one is the best
suitable for any large clustered data center. HT-Paxos further offloads the
leader very significantly and hence increases the throughput and scalability of
the system. While at the same time, among high throughput state-machine
replication protocols, HT-Paxos provides reasonably low latency and response
time
The STRESS Method for Boundary-point Performance Analysis of End-to-end Multicast Timer-Suppression Mechanisms
Evaluation of Internet protocols usually uses random scenarios or scenarios
based on designers' intuition. Such approach may be useful for average-case
analysis but does not cover boundary-point (worst or best-case) scenarios. To
synthesize boundary-point scenarios a more systematic approach is needed.In
this paper, we present a method for automatic synthesis of worst and best case
scenarios for protocol boundary-point evaluation.
Our method uses a fault-oriented test generation (FOTG) algorithm for
searching the protocol and system state space to synthesize these scenarios.
The algorithm is based on a global finite state machine (FSM) model. We extend
the algorithm with timing semantics to handle end-to-end delays and address
performance criteria. We introduce the notion of a virtual LAN to represent
delays of the underlying multicast distribution tree. The algorithms used in
our method utilize implicit backward search using branch and bound techniques
and start from given target events. This aims to reduce the search complexity
drastically. As a case study, we use our method to evaluate variants of the
timer suppression mechanism, used in various multicast protocols, with respect
to two performance criteria: overhead of response messages and response time.
Simulation results for reliable multicast protocols show that our method
provides a scalable way for synthesizing worst-case scenarios automatically.
Results obtained using stress scenarios differ dramatically from those obtained
through average-case analyses. We hope for our method to serve as a model for
applying systematic scenario generation to other multicast protocols.Comment: 24 pages, 10 figures, IEEE/ACM Transactions on Networking (ToN) [To
appear
vSkyConf: Cloud-assisted Multi-party Mobile Video Conferencing
As an important application in the busy world today, mobile video
conferencing facilitates virtual face-to-face communication with friends,
families and colleagues, via their mobile devices on the move. However, how to
provision high-quality, multi-party video conferencing experiences over mobile
devices is still an open challenge. The fundamental reason behind is the lack
of computation and communication capacities on the mobile devices, to scale to
large conferencing sessions. In this paper, we present vSkyConf, a
cloud-assisted mobile video conferencing system to fundamentally improve the
quality and scale of multi-party mobile video conferencing. By novelly
employing a surrogate virtual machine in the cloud for each mobile user, we
allow fully scalable communication among the conference participants via their
surrogates, rather than directly. The surrogates exchange conferencing streams
among each other, transcode the streams to the most appropriate bit rates, and
buffer the streams for the most efficient delivery to the mobile recipients. A
fully decentralized, optimal algorithm is designed to decide the best paths of
streams and the most suitable surrogates for video transcoding along the paths,
such that the limited bandwidth is fully utilized to deliver streams of the
highest possible quality to the mobile recipients. We also carefully tailor a
buffering mechanism on each surrogate to cooperate with optimal stream
distribution. We have implemented vSkyConf based on Amazon EC2 and verified the
excellent performance of our design, as compared to the widely adopted unicast
solutions.Comment: 10 page
On the experimentation of the novel GCMR multicast routing in a large-scale testbed
Originally defined in the 90s, multicast is nowadays (re)gaining interest given the increasing popularity of multimedia streaming/content traffic and the explosion of cloud services. In fact, multicast yields bandwidth savings complementing cached content distribution techniques and its potential benefits have been verified by studies several times since then (see e.g. [1]). By multicast routing, we refer to a distributed algorithm that, given a group identifier, allows any node to route multicast traffic to a group of destination nodes, usually called multicast group. To enable one-to-many traffic distribution, the multicast routing protocol configures the involved routers to build a (logical) delivery tree between the source and the multicast group, commonly referred to as the Multicast Distribution Tree (MDT). Nevertheless, the scaling problems faced in the 90s still remain mostly unaddressed and worst-case projections predict indeed that routing engines could have to process and maintain in the order of 1 million active routes within the next 5 years [2].This work has been partially funded by the EULER FP7-258307 and DOMINO (TEC2010-18522) projects.Peer ReviewedPostprint (author's final draft
Analysis domain model for shared virtual environments
The field of shared virtual environments, which also
encompasses online games and social 3D environments, has a
system landscape consisting of multiple solutions that share great functional overlap. However, there is little system interoperability between the different solutions. A shared virtual environment has an associated problem domain that is highly complex raising difficult challenges to the development process, starting with the architectural design of the underlying system. This paper has two main contributions. The first contribution is a broad domain analysis of shared virtual environments, which enables developers to have a better understanding of the whole rather than the part(s). The second contribution is a reference domain model for discussing and describing solutions - the Analysis Domain Model
Optimal False-Positive-Free Bloom Filter Design for Scalable Multicast Forwarding
Large-scale information dissemination in multicast communications has been increasingly attracting attention, be it through uptake in new services or through recent research efforts. In these the core issues are supporting increased forwarding speed, avoiding state in the forwarding elements and scaling in terms of the multicast tree size. This paper addresses all these challenges – which are crucial for any scalable multicast scheme to be successful – by revisiting the idea of in-packet Bloom filters and source routing. As opposed to the traditional in-packet Bloom filter concept, we build our Bloom filter by enclosing limited information about the structure of the tree. Analytical investigation is conducted and approximation formulae are provided for optimal length Bloom filters, in which we got rid of typical Bloom filter illnesses such as false-positive forwarding. These filters can be used in several multicast implementations, which is demonstrated through a prototype. Thorough simulations are conducted to demonstrate the scalability of the proposed Bloom filters compared to its counterparts
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