32,527 research outputs found
Traffic-Redundancy Aware Network Design
We consider network design problems for information networks where routers
can replicate data but cannot alter it. This functionality allows the network
to eliminate data-redundancy in traffic, thereby saving on routing costs. We
consider two problems within this framework and design approximation
algorithms.
The first problem we study is the traffic-redundancy aware network design
(RAND) problem. We are given a weighted graph over a single server and many
clients. The server owns a number of different data packets and each client
desires a subset of the packets; the client demand sets form a laminar set
system. Our goal is to connect every client to the source via a single path,
such that the collective cost of the resulting network is minimized. Here the
transportation cost over an edge is its weight times times the number of
distinct packets that it carries.
The second problem is a facility location problem that we call RAFL. Here the
goal is to find an assignment from clients to facilities such that the total
cost of routing packets from the facilities to clients (along unshared paths),
plus the total cost of "producing" one copy of each desired packet at each
facility is minimized.
We present a constant factor approximation for the RAFL and an O(log P)
approximation for RAND, where P is the total number of distinct packets. We
remark that P is always at most the number of different demand sets desired or
the number of clients, and is generally much smaller.Comment: 17 pages. To be published in the proceedings of the Twenty-Third
Annual ACM-SIAM Symposium on Discrete Algorithm
A Survey of Green Networking Research
Reduction of unnecessary energy consumption is becoming a major concern in
wired networking, because of the potential economical benefits and of its
expected environmental impact. These issues, usually referred to as "green
networking", relate to embedding energy-awareness in the design, in the devices
and in the protocols of networks. In this work, we first formulate a more
precise definition of the "green" attribute. We furthermore identify a few
paradigms that are the key enablers of energy-aware networking research. We
then overview the current state of the art and provide a taxonomy of the
relevant work, with a special focus on wired networking. At a high level, we
identify four branches of green networking research that stem from different
observations on the root causes of energy waste, namely (i) Adaptive Link Rate,
(ii) Interface proxying, (iii) Energy-aware infrastructures and (iv)
Energy-aware applications. In this work, we do not only explore specific
proposals pertaining to each of the above branches, but also offer a
perspective for research.Comment: Index Terms: Green Networking; Wired Networks; Adaptive Link Rate;
Interface Proxying; Energy-aware Infrastructures; Energy-aware Applications.
18 pages, 6 figures, 2 table
Energy management in communication networks: a journey through modelling and optimization glasses
The widespread proliferation of Internet and wireless applications has
produced a significant increase of ICT energy footprint. As a response, in the
last five years, significant efforts have been undertaken to include
energy-awareness into network management. Several green networking frameworks
have been proposed by carefully managing the network routing and the power
state of network devices.
Even though approaches proposed differ based on network technologies and
sleep modes of nodes and interfaces, they all aim at tailoring the active
network resources to the varying traffic needs in order to minimize energy
consumption. From a modeling point of view, this has several commonalities with
classical network design and routing problems, even if with different
objectives and in a dynamic context.
With most researchers focused on addressing the complex and crucial
technological aspects of green networking schemes, there has been so far little
attention on understanding the modeling similarities and differences of
proposed solutions. This paper fills the gap surveying the literature with
optimization modeling glasses, following a tutorial approach that guides
through the different components of the models with a unified symbolism. A
detailed classification of the previous work based on the modeling issues
included is also proposed
Recommended from our members
Intra- and Inter-Session Network Coding in Wireless Networks
In this paper, we are interested in improving the performance of constructive
network coding schemes in lossy wireless environments.We propose I2NC - a
cross-layer approach that combines inter-session and intra-session network
coding and has two strengths. First, the error-correcting capabilities of
intra-session network coding make our scheme resilient to loss. Second,
redundancy allows intermediate nodes to operate without knowledge of the
decoding buffers of their neighbors. Based only on the knowledge of the loss
rates on the direct and overhearing links, intermediate nodes can make
decisions for both intra-session (i.e., how much redundancy to add in each
flow) and inter-session (i.e., what percentage of flows to code together)
coding. Our approach is grounded on a network utility maximization (NUM)
formulation of the problem. We propose two practical schemes, I2NC-state and
I2NC-stateless, which mimic the structure of the NUM optimal solution. We also
address the interaction of our approach with the transport layer. We
demonstrate the benefits of our schemes through simulations
- …