Networked Music Performance (NMP) constitutes a class of ultra-low delay sensitive applications, allowing geographically separate musicians to perform seamlessly as a tele-orchestra. For this application type, the QoS indicator is the mouth-to-ear delay, which should be kept under 25 milliseconds. The mouth-to-ear delay comprises signal processing latency and network delay. We propose a strong collaboration between the network and NMP applications to actively keep the to mouth-to-ear delay minimal, using direct state notifications. Related approaches can be characterized as passive, since they try to estimate the network state indirectly, based on the end application performance. Our solution employs Software Defined Networking (SDN) to implement the network-to-application collaboration, being facilitated by the well-defined network interface that SDN offers. Emulation results show that the proposed scheme achieves an improvement of up to 59 in mouth-to-ear delay over the existing passive solutions.
From the network perspective, SDN is widely used in network condition-aware applications @cite_12 @cite_3 @cite_8 @cite_2 . The main feature is that traffic is prioritized using criteria such as Type of Service (TOS), requirements, SLAs or packet header fields @cite_11 @cite_21 @cite_27 @cite_23 . Moreover, SIP combined with SDN is introduced also in @cite_10 where an approach for VoIP applications is described by codec modification due to network changes. Finally, in @cite_29 an alternative method for collecting network statistics is introduced where SDN Controller sends periodically requests to switches about statistics. This information is used for network delay monitoring by SDN Controller.
@cite_8 @cite_29 @cite_21 @cite_3 @cite_27 @cite_23 @cite_2 @cite_10 @cite_12 @cite_11
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In software-defined networking (SDN), a software controller manages a distributed collection of switches by installing and uninstalling packet-forwarding rules in the switches. SDNs allow flexible implementations for expressive and sophisticated network management policies. We consider the problem of verifying that an SDN satisfies a given safety property. We describe Kuai, a distributed enumerative model checker for SDNs. Kuai takes as input a controller implementation written in Murphi, a description of the network topology (switches and connections), and a safety property, and performs a distributed enumerative reachability analysis on a cluster of machines. Kuai uses a set of partial order reduction techniques specific to the SDN domain that help reduce the state space dramatically. In addition, Kuai performs an automatic abstraction to handle unboundedly many packets traversing the network at a given time and unboundedly many control messages between the controller and the switches. We demonstrate the scalability and coverage of Kuai on standard SDN benchmarks. We show that our set of partial order reduction techniques significantly reduces the state spaces of these benchmarks by many orders of magnitude. In addition, Kuai exploits large-scale distribution to quickly search the reduced state space. Software defined networks (SDNs) introduced the concept of decoupling control and data planes which is a paradigm shift. The OpenFlow protocol is one of a number of technologies that enables this decoupling and, in effect, commodifies network equipment. As of now, there is still limited work that has been done towards modeling the transit delay across OpenFlow switches experienced by network traffic. In this work we develop a stochastic model for the path latency in Open vSwitch (used together with a POX controller) based on measurements made in experiments performed on three different platforms which include 1) Mininet, 2) MikroTik RouterBoard 750GL and 3) GENI testbed softswitch. We propose a log-normal mix model (LNMM) and show that it offers a R2 value of greater than 0.90 for most of our experiments. We also demonstrate how the M M 1 models proposed in earlier studies is a poor fit. In Software Defined Networks (SDN), intensive traffic monitoring is used to optimize the Quality-of-Service (QoS) of the network paths which are selected. Thus, we introduce the use of the Cognitive Packet Network (CPN) algorithm to SDN in order to optimize the search for new high-QoS paths. We install the CPN algorithm in the Cognitive Routing Engine (CRE), a new application software for SDN, and show that with limited monitoring overhead we are able to determine the near-optimal paths for given QoS metrics that may be proposed by the end users. Measurements that we have conducted on an experimental replica of the GEANT network that our approach uses close to 10 times less monitoring data than conventional SDN, but that we are able to approach the optimal paths within 2 . Software Defined Networking (SDN) provides opportunities for network verification and debugging by offering centralized visibility of the data plane. This has enabled both offline and online data-plane verification. However, little work has gone into the verification of time-varying properties (e.g., dynamic access control), where verification conditions change dynamically in response to application logic, network events, and external stimulus (e.g., operator requests). This paper introduces an assertion language to support verifying and debugging SDN applications with dynamically changing verification conditions. The language allows programmers to annotate controller applications with C-style assertions about the data plane. Assertions consist of regular expressions on paths to describe path properties for classes of packets, and universal and existential quantifiers that range over programmer-defined sets of hosts, switches, or other network entities. As controller programs dynamically add and remove elements from these sets, they generate new verification conditions that the existing data plane must satisfy. This work proposes an incremental data structure together with an underlying verification engine, to avoid naively re-verifying the entire data plane as these verification conditions change. To validate our ideas, we have implemented a debugging library on top of a modified version of VeriFlow, which is easily integrated into existing controller systems with minimal changes. Using this library, we have verified correctness properties for applications on several controller platforms.