Global and local knowledge in SDN

Czachórski

2021

Sensors

The increasing use of Software-Defined Networks brings the need for their performance analysis and detailed analytical and numerical models of them. The primary element of such research is a model of a SDN switch. This model should take into account non-Poisson traffic and general distributions of service times. Because of frequent changes in SDN flows, it should also analyze transient states of the queues. The method of diffusion approximation can meet these requirements. We present here a diffusion approximation of priority queues and apply it to build a more detailed model of SDN switch where packets returned by the central controller have higher priority than other packets.

Section: Introduction and An Overview Of Existing Resultsmentioning

confidence: 99%

Diffusion Model of Preemptive-Resume Priority Systems and Its Application to Performance Evaluation of SDN Switches

Czachórski

2021

Sensors

Trans. Emerging Tel. Tech.

“…They do not have complete information about paths for all flows established in the network, although statistics remain available. An adequate balance between local and global knowledge is key to achieving scalability in decentralized SDN architectures because global knowledge is not needed in many cases . For instance, Section 5.6.2 shows how a controller‐based stateless firewall can be easily configured without losing its functionality.…”

Section: Discussionmentioning

confidence: 99%

“…Regarding delegation of control, several proposals in the literature deal with bottlenecks in controllers by decentralizing the SDN control plane, and a hardware and software upgrade both at the switches and at the controller as in previous studies . Another study examines the concept of global and local knowledge to determine whether an SDN application should reside in the control or in the data plane, proposes an API for programming the generation of packets in SDN switches (it presents the example of an ARP handler in the data plane). Other approaches propose to exploit parallel execution on the controllers, the synchronization of network state among multiple controller instances, or a distributed or hierarchical platform of SDN controllers.…”

Section: Related Workmentioning

confidence: 99%

New cooperative mechanisms for software defined networks based on hybrid switches

Alvarez-Horcajo

Martínez-Yelmo

Rojas³

et al. 2017

Software defined networking (SDN) aims to provide simplified network design, operation, and management using a decoupled control plane. However, its centralized control and global network knowledge present scalability and reliability issues, which makes SDN deployment very challenging. In this paper, we propose and evaluate a hybrid switch with partial delegation of basic bridging and new cooperative mechanisms between controller and switches. This delegation offloads the SDN controllers while maintaining the capability to install forwarding rules on the switches. In this way, we take full advantage of hybrid switches in addition to using them as backwards compatible equipment, which interoperates with traditional switches.We validate this proposal by implementing a hybrid OpenFlow switch on an open source software switch as a proof of concept. Scalability and path setup delay are improved with respect to traditional centralized SDN solutions, because of the reduction in controller load and, in turn, because of the reduced traffic between switches and controller. Our cooperative mechanisms focus on recovering failures, obtaining the best performance of all approaches on higher loads, and providing a good trade‐off between controller based and traditional distributed approaches.

“…If all the services are provided in a single network infrastructure, the development of the network will be very complicated and adapting to a variety of functional requirements will be difficult. In this regard, SDN provides a new direction of networking services and drastically changes the traditional network with distinctive features including the separation of controller and forwarding unit, virtualization, programmable service, dynamic reconfiguration, and centralized management [3].…”

Section: Introductionmentioning

confidence: 99%

Entry Aggregation and Early Match Using Hidden Markov Model of Flow Table in SDN

Wang

Youn

2019

Sensors

The usage of multiple flow tables (MFT) has significantly extended the flexibility and applicability of software-defined networking (SDN). However, the size of MFT is usually limited due to the use of expensive ternary content addressable memory (TCAM). Moreover, the pipeline mechanism of MFT causes long flow processing time. In this paper a novel approach called Agg-ExTable is proposed to efficiently manage the MFT. Here the flow entries in MFT are periodically aggregated by applying pruning and the Quine–Mccluskey algorithm. Utilizing the memory space saved by the aggregation, a front-end ExTable is constructed, keeping popular flow entries for early match. Popular entries are decided by the Hidden Markov model based on the match frequency and match probability. Computer simulation reveals that the proposed scheme is able to save about 45% of space of MFT, and efficiently decrease the flow processing time compared to the existing schemes.