2,574 research outputs found
Online Multicast Traffic Engineering for Software-Defined Networks
Previous research on SDN traffic engineering mostly focuses on static
traffic, whereas dynamic traffic, though more practical, has drawn much less
attention. Especially, online SDN multicast that supports IETF dynamic group
membership (i.e., any user can join or leave at any time) has not been
explored. Different from traditional shortest-path trees (SPT) and graph
theoretical Steiner trees (ST), which concentrate on routing one tree at any
instant, online SDN multicast traffic engineering is more challenging because
it needs to support dynamic group membership and optimize a sequence of
correlated trees without the knowledge of future join and leave, whereas the
scalability of SDN due to limited TCAM is also crucial. In this paper,
therefore, we formulate a new optimization problem, named Online Branch-aware
Steiner Tree (OBST), to jointly consider the bandwidth consumption, SDN
multicast scalability, and rerouting overhead. We prove that OBST is NP-hard
and does not have a -competitive algorithm for any
, where is the largest group size at any time. We
design a -competitive algorithm equipped with the notion of the
budget, the deposit, and Reference Tree to achieve the tightest bound. The
simulations and implementation on real SDNs with YouTube traffic manifest that
the total cost can be reduced by at least 25% compared with SPT and ST, and the
computation time is small for massive SDN.Comment: Full version (accepted by INFOCOM 2018
Scheduling for Weighted Flow and Completion Times in Reconfigurable Networks
New optical technologies offer the ability to reconfigure network topologies
dynamically, rather than setting them once and for all. This is true in both
optical wide area networks (optical WANs) and in datacenters, despite the many
differences between these two settings. Because of these new technologies,
there has been a surge of both practical and theoretical research on algorithms
to take advantage of them. In particular, Jia et al. [INFOCOM '17] designed
online scheduling algorithms for dynamically reconfigurable topologies for both
the makespan and sum of completion times objectives. In this paper, we work in
the same setting but study an objective that is more meaningful in an online
setting: the sum of flow times. The flow time of a job is the total amount of
time that it spends in the system, which may be considerably smaller than its
completion time if it is released late. We provide competitive algorithms for
the online setting with speed augmentation, and also give a lower bound proving
that speed augmentation is in fact necessary. As a side effect of our
techniques, we also improve and generalize the results of Jia et al. on
completion times by giving an -competitive algorithm for arbitrary sizes
and release times even when nodes have different degree bounds, and moreover
allow for the weighted sum of completion times (or flow times).Comment: 10 pages. Appears in INFOCOM 202
Datacenter Traffic Control: Understanding Techniques and Trade-offs
Datacenters provide cost-effective and flexible access to scalable compute
and storage resources necessary for today's cloud computing needs. A typical
datacenter is made up of thousands of servers connected with a large network
and usually managed by one operator. To provide quality access to the variety
of applications and services hosted on datacenters and maximize performance, it
deems necessary to use datacenter networks effectively and efficiently.
Datacenter traffic is often a mix of several classes with different priorities
and requirements. This includes user-generated interactive traffic, traffic
with deadlines, and long-running traffic. To this end, custom transport
protocols and traffic management techniques have been developed to improve
datacenter network performance.
In this tutorial paper, we review the general architecture of datacenter
networks, various topologies proposed for them, their traffic properties,
general traffic control challenges in datacenters and general traffic control
objectives. The purpose of this paper is to bring out the important
characteristics of traffic control in datacenters and not to survey all
existing solutions (as it is virtually impossible due to massive body of
existing research). We hope to provide readers with a wide range of options and
factors while considering a variety of traffic control mechanisms. We discuss
various characteristics of datacenter traffic control including management
schemes, transmission control, traffic shaping, prioritization, load balancing,
multipathing, and traffic scheduling. Next, we point to several open challenges
as well as new and interesting networking paradigms. At the end of this paper,
we briefly review inter-datacenter networks that connect geographically
dispersed datacenters which have been receiving increasing attention recently
and pose interesting and novel research problems.Comment: Accepted for Publication in IEEE Communications Surveys and Tutorial
On the Rollout of Network Slicing in Carrier Networks: A Technology Radar
Network slicing is a powerful paradigm for network operators to support use cases with
widely diverse requirements atop a common infrastructure. As 5G standards are completed, and
commercial solutions mature, operators need to start thinking about how to integrate network slicing
capabilities in their assets, so that customer-facing solutions can be made available in their portfolio.
This integration is, however, not an easy task, due to the heterogeneity of assets that typically exist
in carrier networks. In this regard, 5G commercial networks may consist of a number of domains,
each with a different technological pace, and built out of products from multiple vendors, including
legacy network devices and functions. These multi-technology, multi-vendor and brownfield features
constitute a challenge for the operator, which is required to deploy and operate slices across all these
domains in order to satisfy the end-to-end nature of the services hosted by these slices. In this context,
the only realistic option for operators is to introduce slicing capabilities progressively, following a
phased approach in their roll-out. The purpose of this paper is to precisely help designing this kind
of plan, by means of a technology radar. The radar identifies a set of solutions enabling network
slicing on the individual domains, and classifies these solutions into four rings, each corresponding
to a different timeline: (i) as-is ring, covering today’s slicing solutions; (ii) deploy ring, corresponding
to solutions available in the short term; (iii) test ring, considering medium-term solutions; and
(iv) explore ring, with solutions expected in the long run. This classification is done based on the
technical availability of the solutions, together with the foreseen market demands. The value of this
radar lies in its ability to provide a complete view of the slicing landscape with one single snapshot,
by linking solutions to information that operators may use for decision making in their individual
go-to-market strategies.H2020 European Projects 5G-VINNI (grant agreement No. 815279) and 5G-CLARITY (grant agreement No. 871428)Spanish national project TRUE-5G (PID2019-108713RB-C53
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