27,171 research outputs found
Space Shuffle: A Scalable, Flexible, and High-Bandwidth Data Center Network
Data center applications require the network to be scalable and
bandwidth-rich. Current data center network architectures often use rigid
topologies to increase network bandwidth. A major limitation is that they can
hardly support incremental network growth. Recent work proposes to use random
interconnects to provide growth flexibility. However routing on a random
topology suffers from control and data plane scalability problems, because
routing decisions require global information and forwarding state cannot be
aggregated. In this paper we design a novel flexible data center network
architecture, Space Shuffle (S2), which applies greedy routing on multiple ring
spaces to achieve high-throughput, scalability, and flexibility. The proposed
greedy routing protocol of S2 effectively exploits the path diversity of
densely connected topologies and enables key-based routing. Extensive
experimental studies show that S2 provides high bisectional bandwidth and
throughput, near-optimal routing path lengths, extremely small forwarding
state, fairness among concurrent data flows, and resiliency to network
failures
Distributed Collaborative Monitoring in Software Defined Networks
We propose a Distributed and Collaborative Monitoring system, DCM, with the
following properties. First, DCM allow switches to collaboratively achieve flow
monitoring tasks and balance measurement load. Second, DCM is able to perform
per-flow monitoring, by which different groups of flows are monitored using
different actions. Third, DCM is a memory-efficient solution for switch data
plane and guarantees system scalability. DCM uses a novel two-stage Bloom
filters to represent monitoring rules using small memory space. It utilizes the
centralized SDN control to install, update, and reconstruct the two-stage Bloom
filters in the switch data plane. We study how DCM performs two representative
monitoring tasks, namely flow size counting and packet sampling, and evaluate
its performance. Experiments using real data center and ISP traffic data on
real network topologies show that DCM achieves highest measurement accuracy
among existing solutions given the same memory budget of switches
Kinematic Basis of Emergent Energetics of Complex Dynamics
Stochastic kinematic description of a complex dynamics is shown to dictate an
energetic and thermodynamic structure. An energy function emerges
as the limit of the generalized, nonequilibrium free energy of a Markovian
dynamics with vanishing fluctuations. In terms of the and its
orthogonal field , a general vector field
can be decomposed into , where
.
The matrix and scalar , two additional characteristics to the
alone, represent the local geometry and density of states intrinsic to
the statistical motion in the state space at . and
are interpreted as the emergent energy and degeneracy of the motion, with an
energy balance equation ,
reflecting the geometrical . The
partition function employed in statistical mechanics and J. W. Gibbs' method of
ensemble change naturally arise; a fluctuation-dissipation theorem is
established via the two leading-order asymptotics of entropy production as
. The present theory provides a mathematical basis for P. W.
Anderson's emergent behavior in the hierarchical structure of complexity
science.Comment: 7 page
A Comprehensive Four-Quark Interpretation of D_s(2317), D_s(2457) and D_s(2632)
The recently observed new member of the charm-strange family D_s(2632) which
has a surprisingly narrow width is challenging our theory. D_s(2317) and
D_s(2457) which were observed earlier have similar behaviors and receive
various theoretical explanations. Some authors use the heavy hadron chiral
effective theory to evaluate heavy-light quark systems and obtain a reasonable
evaluation on the masses of D_s(2317) and D_s(2457). An alternative picture is
to interpret them as four-quark or molecular states. In this work, we are
following the later and propose a unitive description for all the three new
members D_s(2632), D_s(2317) and D_s(2457) and at least, so far our picture is
consistent with the data.Comment: 6 page
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