6,937 research outputs found
A new lookup model for multiple flow tables of open flow with implementation and optimization considerations
This is the author accepted manuscript. The final version is available from IEEE via the DOI in this record.Open Flow has become the key standard for the southbound interface of software defined networking. The single flow table of Open Flow implementation can lead to fast storage space growth, and finally cause table-overflow, the multiple flow tables can address this problem and provide greater efficiency and flexibility. Through analyzing the potential deployment challenges of Open Flow, this paper proposes a new lookup model with implementation and optimization considerations for multiple flow tables in an Open Flow switch. With the developed lookup model, the original single flow table is split into multiple sub-flow tables, and the fields in each sub-flow table are further divided into several categories according to different field types. Preliminary simulation results demonstrate that the proposed solution can effectively reduce the storage space of flow tables
Segment Routing: a Comprehensive Survey of Research Activities, Standardization Efforts and Implementation Results
Fixed and mobile telecom operators, enterprise network operators and cloud
providers strive to face the challenging demands coming from the evolution of
IP networks (e.g. huge bandwidth requirements, integration of billions of
devices and millions of services in the cloud). Proposed in the early 2010s,
Segment Routing (SR) architecture helps face these challenging demands, and it
is currently being adopted and deployed. SR architecture is based on the
concept of source routing and has interesting scalability properties, as it
dramatically reduces the amount of state information to be configured in the
core nodes to support complex services. SR architecture was first implemented
with the MPLS dataplane and then, quite recently, with the IPv6 dataplane
(SRv6). IPv6 SR architecture (SRv6) has been extended from the simple steering
of packets across nodes to a general network programming approach, making it
very suitable for use cases such as Service Function Chaining and Network
Function Virtualization. In this paper we present a tutorial and a
comprehensive survey on SR technology, analyzing standardization efforts,
patents, research activities and implementation results. We start with an
introduction on the motivations for Segment Routing and an overview of its
evolution and standardization. Then, we provide a tutorial on Segment Routing
technology, with a focus on the novel SRv6 solution. We discuss the
standardization efforts and the patents providing details on the most important
documents and mentioning other ongoing activities. We then thoroughly analyze
research activities according to a taxonomy. We have identified 8 main
categories during our analysis of the current state of play: Monitoring,
Traffic Engineering, Failure Recovery, Centrally Controlled Architectures, Path
Encoding, Network Programming, Performance Evaluation and Miscellaneous...Comment: SUBMITTED TO IEEE COMMUNICATIONS SURVEYS & TUTORIAL
An Evaluation of Heat Exchangers Using System Information and PEC
This report describes analyses aimed at integrating component optimization and
system design by developing heat-exchanger performance evaluation criteria (PEC) that
account for the system-level performance impacts of heat exchanger design. It builds on
earlier studies that used relatively simple PEC to capture some of the component-level
tradeoffs, but which usually ignore the system impact of component design. This report
evaluates four PEC-j/f, heat transfer/pumping power (8), heat transfer/(pumping +
compressor power) (n), and system COP. It is shown that j/f and 8 are better used as
comparison criteria for existing heat exchangers of equal heat duty rather than as design
criteria. The other two PEC, n and COP, include the system effect of compressor
efficiency and therefore can be used more effectively in heat exchanger and system
design. Through a combination of PEC and system optimization techniques, a method is
developed to evaluate and design heat exchangers for maximum system performance.Air Conditioning and Refrigeration Project 9
SDNsec: Forwarding Accountability for the SDN Data Plane
SDN promises to make networks more flexible, programmable, and easier to
manage. Inherent security problems in SDN today, however, pose a threat to the
promised benefits. First, the network operator lacks tools to proactively
ensure that policies will be followed or to reactively inspect the behavior of
the network. Second, the distributed nature of state updates at the data plane
leads to inconsistent network behavior during reconfigurations. Third, the
large flow space makes the data plane susceptible to state exhaustion attacks.
This paper presents SDNsec, an SDN security extension that provides
forwarding accountability for the SDN data plane. Forwarding rules are encoded
in the packet, ensuring consistent network behavior during reconfigurations and
limiting state exhaustion attacks due to table lookups. Symmetric-key
cryptography is used to protect the integrity of the forwarding rules and
enforce them at each switch. A complementary path validation mechanism allows
the controller to reactively examine the actual path taken by the packets.
Furthermore, we present mechanisms for secure link-failure recovery and
multicast/broadcast forwarding.Comment: 14 page
Data Structures and Algorithms for Scalable NDN Forwarding
Named Data Networking (NDN) is a recently proposed general-purpose network architecture that aims to address the limitations of the Internet Protocol (IP), while maintaining its strengths. NDN takes an information-centric approach, focusing on named data rather than computer addresses. In NDN, the content is identified by its name, and each NDN packet has a name that specifies the content it is fetching or delivering. Since there are no source and destination addresses in an NDN packet, it is forwarded based on a lookup of its name in the forwarding plane, which consists of the Forwarding Information Base (FIB), Pending Interest Table (PIT), and Content Store (CS). In addition, as an in-network caching element, a scalable Repository (Repo) design is needed to provide large-scale long-term content storage in NDN networks.
Scalable NDN forwarding is a challenge. Compared to the well-understood approaches to IP forwarding, NDN forwarding performs lookups on packet names, which have variable and unbounded lengths, increasing the lookup complexity. The lookup tables are larger than in IP, requiring more memory space. Moreover, NDN forwarding has a read-write data plane, requiring per-packet updates at line rates. Designing and evaluating a scalable NDN forwarding node architecture is a major effort within the overall NDN research agenda.
The goal of this dissertation is to demonstrate that scalable NDN forwarding is feasible with the proposed data structures and algorithms. First, we propose a FIB lookup design based on the binary search of hash tables that provides a reliable longest name prefix lookup performance baseline for future NDN research. We have demonstrated 10 Gbps forwarding throughput with 256-byte packets and one billion synthetic forwarding rules, each containing up to seven name components. Second, we explore data structures and algorithms to optimize the FIB design based on the specific characteristics of real-world forwarding datasets. Third, we propose a fingerprint-only PIT design that reduces the memory requirements in the core routers. Lastly, we discuss the Content Store design issues and demonstrate that the NDN Repo implementation can leverage many of the existing databases and storage systems to improve performance
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