166 research outputs found
The heterogeneity of inter-contact time distributions: its importance for routing in delay tolerant networks
Prior work on routing in delay tolerant networks (DTNs) has commonly made the
assumption that each pair of nodes shares the same inter-contact time
distribution as every other pair. The main argument in this paper is that
researchers should also be looking at heterogeneous inter-contact time
distributions. We demonstrate the presence of such heterogeneity in the
often-used Dartmouth Wi-Fi data set. We also show that DTN routing can benefit
from knowing these distributions. We first introduce a new stochastic model
focusing on the inter-contact time distributions between all pairs of nodes,
which we validate on real connectivity patterns. We then analytically derive
the mean delivery time for a bundle of information traversing the network for
simple single copy routing schemes. The purpose is to examine the theoretic
impact of heterogeneous inter-contact time distributions. Finally, we show that
we can exploit this user diversity to improve routing performance.Comment: 6 page
Evaluating Mobility Pattern Space Routing for DTNs
Because a delay tolerant network (DTN) can often be partitioned, the problem
of routing is very challenging. However, routing benefits considerably if one
can take advantage of knowledge concerning node mobility. This paper addresses
this problem with a generic algorithm based on the use of a high-dimensional
Euclidean space, that we call MobySpace, constructed upon nodes' mobility
patterns. We provide here an analysis and the large scale evaluation of this
routing scheme in the context of ambient networking by replaying real mobility
traces. The specific MobySpace evaluated is based on the frequency of visit of
nodes for each possible location. We show that the MobySpace can achieve good
performance compared to that of the other algorithms we implemented, especially
when we perform routing on the nodes that have a high connection time. We
determine that the degree of homogeneity of mobility patterns of nodes has a
high impact on routing. And finally, we study the ability of nodes to learn
their own mobility patterns.Comment: IEEE INFOCOM 2006 preprin
Implementation and Deployment of a Distributed Network Topology Discovery Algorithm
In the past few years, the network measurement community has been interested
in the problem of internet topology discovery using a large number (hundreds or
thousands) of measurement monitors. The standard way to obtain information
about the internet topology is to use the traceroute tool from a small number
of monitors. Recent papers have made the case that increasing the number of
monitors will give a more accurate view of the topology. However, scaling up
the number of monitors is not a trivial process. Duplication of effort close to
the monitors wastes time by reexploring well-known parts of the network, and
close to destinations might appear to be a distributed denial-of-service (DDoS)
attack as the probes converge from a set of sources towards a given
destination. In prior work, authors of this report proposed Doubletree, an
algorithm for cooperative topology discovery, that reduces the load on the
network, i.e., router IP interfaces and end-hosts, while discovering almost as
many nodes and links as standard approaches based on traceroute. This report
presents our open-source and freely downloadable implementation of Doubletree
in a tool we call traceroute@home. We describe the deployment and validation of
traceroute@home on the PlanetLab testbed and we report on the lessons learned
from this experience. We discuss how traceroute@home can be developed further
and discuss ideas for future improvements
Multilevel MDA-Lite Paris Traceroute
Since its introduction in 2006-2007, Paris Traceroute and its Multipath
Detection Algorithm (MDA) have been used to conduct well over a billion IP
level multipath route traces from platforms such as M-Lab. Unfortunately, the
MDA requires a large number of packets in order to trace an entire topology of
load balanced paths between a source and a destination, which makes it
undesirable for platforms that otherwise deploy Paris Traceroute, such as RIPE
Atlas. In this paper we present a major update to the Paris Traceroute tool.
Our contributions are: (1) MDA-Lite, an alternative to the MDA that
significantly cuts overhead while maintaining a low failure probability; (2)
Fakeroute, a simulator that enables validation of a multipath route tracing
tool's adherence to its claimed failure probability bounds; (3) multilevel
multipath route tracing, with, for the first time, a Traceroute tool that
provides a router-level view of multipath routes; and (4) surveys at both the
IP and router levels of multipath routing in the Internet, showing, among other
things, that load balancing topologies have increased in size well beyond what
has been previously reported as recently as 2016. The data and the software
underlying these results are publicly available.Comment: Preprint. To appear in Proc. ACM Internet Measurement Conference 201
Retouched Bloom Filters: Allowing Networked Applications to Flexibly Trade Off False Positives Against False Negatives
Where distributed agents must share voluminous set membership information,
Bloom filters provide a compact, though lossy, way for them to do so. Numerous
recent networking papers have examined the trade-offs between the bandwidth
consumed by the transmission of Bloom filters, and the error rate, which takes
the form of false positives, and which rises the more the filters are
compressed. In this paper, we introduce the retouched Bloom filter (RBF), an
extension that makes the Bloom filter more flexible by permitting the removal
of selected false positives at the expense of generating random false
negatives. We analytically show that RBFs created through a random process
maintain an overall error rate, expressed as a combination of the false
positive rate and the false negative rate, that is equal to the false positive
rate of the corresponding Bloom filters. We further provide some simple
heuristics and improved algorithms that decrease the false positive rate more
than than the corresponding increase in the false negative rate, when creating
RBFs. Finally, we demonstrate the advantages of an RBF over a Bloom filter in a
distributed network topology measurement application, where information about
large stop sets must be shared among route tracing monitors.Comment: This is a new version of the technical reports with improved
algorithms and theorical analysis of algorithm
Investigating Depth-Fanout Trade-Off in WiMAX Mesh Networks
peer reviewedIn the last years, Wireless Mesh Networks (WMNs) have been an emerging technology for providing cost/effective broadband Internet access. The research done insofar usually assumes that the wireless backbone of a WMN is built using IEEE 802.11 technologies. Such an approach has the drawback of leading to dense and sub-optimal deployments, due to the short transmission range of this standard. Recently standardized, the WiMAX technology is supposed to transcend this limitation by a transmission range of several miles. In particular, the mesh mode of the WiMAX standard enables direct communications between subscriber stations and, hence, reduces dead zones while increasing the global throughput. In this paper, we investigate the throughput capacity of a WiMAX mesh tree. More specifically, we are interested in balancing the impact of the depth of the tree with its fanout. We provide a traffic model and evaluate the WiMAX mesh tree by simulations
Jumps: Enhancing hop-count positioning in sensor networks using multiple coordinates
Positioning systems in self-organizing networks generally rely on
measurements such as delay and received signal strength, which may be difficult
to obtain and often require dedicated equipment. An alternative to such
approaches is to use simple connectivity information, that is, the presence or
absence of a link between any pair of nodes, and to extend it to hop-counts, in
order to obtain an approximate coordinate system. Such an approximation is
sufficient for a large number of applications, such as routing. In this paper,
we propose Jumps, a positioning system for those self-organizing networks in
which other types of (exact) positioning systems cannot be used or are deemed
to be too costly. Jumps builds a multiple coordinate system based solely on
nodes neighborhood knowledge. Jumps is interesting in the context of wireless
sensor networks, as it neither requires additional embedded equipment nor
relies on any nodes capabilities. While other approaches use only three
hop-count measurements to infer the position of a node, Jumps uses an arbitrary
number. We observe that an increase in the number of measurements leads to an
improvement in the localization process, without requiring a high dense
environment. We show through simulations that Jumps, when compared with
existing approaches, reduces the number of nodes sharing the same coordinates,
which paves the way for functions such as position-based routing
Longitudinal Study of an IP Geolocation Database
IP geolocation - the process of mapping network identifiers to physical
locations - has myriad applications. We examine a large collection of snapshots
from a popular geolocation database and take a first look at its longitudinal
properties. We define metrics of IP geo-persistence, prevalence, coverage, and
movement, and analyse 10 years of geolocation data at different location
granularities. Across different classes of IP addresses, we find that
significant location differences can exist even between successive instances of
the database - a previously underappreciated source of potential error when
using geolocation data: 47% of end users IP addresses move by more than 40 km
in 2019. To assess the sensitivity of research results to the instance of the
geo database, we reproduce prior research that depended on geolocation lookups.
In this case study, which analyses geolocation database performance on routers,
we demonstrate impact of these temporal effects: median distance from ground
truth shifted from 167 km to 40 km when using a two months apart snapshot.
Based on our findings, we make recommendations for best practices when using
geolocation databases in order to best encourage reproducibility and sound
measurement.Comment: Technical Report related to a paper appeared in Network Traffic
Measurement and Analysis Conference (TMA 2021
Multitenant Containers as a Service (CaaS) for Clouds and Edge Clouds
Cloud computing, offering on-demand access to computing resources through the
Internet and the pay-as-you-go model, has marked the last decade with its three
main service models; Infrastructure as a Service (IaaS), Platform as a Service
(PaaS), and Software as a Service (SaaS). The lightweight nature of containers
compared to virtual machines has led to the rapid uptake of another in recent
years, called Containers as a Service (CaaS), which falls between IaaS and PaaS
regarding control abstraction. However, when CaaS is offered to multiple
independent users, or tenants, a multi-instance approach is used, in which each
tenant receives its own separate cluster, which reimposes significant overhead
due to employing virtual machines for isolation. If CaaS is to be offered not
just at the cloud, but also at the edge cloud, where resources are limited,
another solution is required. We introduce a native CaaS multitenancy
framework, meaning that tenants share a cluster, which is more efficient than
the one tenant per cluster model. Whenever there are shared resources,
isolation of multitenant workloads is an issue. Such workloads can be isolated
by Kata Containers today. Besides, our framework esteems the application
requirements that compel complete isolation and a fully customized environment.
Node-level slicing empowers tenants to programmatically reserve isolated
subclusters where they can choose the container runtime that suits application
needs. The framework is publicly available as liberally-licensed, free,
open-source software that extends Kubernetes, the de facto standard container
orchestration system. It is in production use within the EdgeNet testbed for
researchers
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