Load Balancing for the Agile All-Photonic Network

The Agile All-Photonic Network (AAPN) uses Time Division Multiplexing (TDM) to better utilize the bandwidth of Wavelength Division Multiplexing (WDM) systems. It uses agile all-photonic switches as advances in the photonic switching technology made the design of all-photonic devices with switching latency in the sub-microseconds feasible. The network has a simplified overlaid star architecture that can be deployed in a Metropolitan Area Network (MAN) or a Wide Area Network (WAN) environment. This overlaid architecture, as opposed to general mesh architecture, scales network capacity to multiples of Tera bits per second, simplif�ies routing, increases reliability, eliminates wavelength conversion, and the need for accurate traffic engineering. The objective of this thesis is to propose and analyze dif�ferent load balancing methods for the deployment of the AAPN network in a WAN environment. The analysis should provide interested Internet Service Providers (ISPs) with a comprehensive study of load balancing methods for using the AAPN network as their backbone network. The methods balance the load at the ow level to reduce packet reordering. The methods are stateless and can compute routes quickly based on the packet flow identi�er. This is an important issue when deploying AAPN as an Internet backbone network where the number of flows is large and storing ow state in lookup tables can limit the network performance. The load balancing methods, deployed at the edge nodes, require reliable signaling with the bandwidth schedulers at the core nodes. To provide a reliable channel between the edge and core nodes, the Control Messages Delivery Protocol (CMDP) is proposed as part of this thesis work. The protocol is designed to work in environments where propagation delays are long and/or the error rates are high. It is used to deliver a burst of short messages in sequence and with no errors. Combined with the reliable routing protocol proposed previously for the AAPN network, they form the control plane for the network. To extend the applicability of the load balancing methods to topologies beyond AAPN overlaid star topology, the Valiant Load Balancing (VLB) method is used to build an overlaid star topology on top of the physical network. The VLB method provides guaranteed performance for highly variable tra�c matrices within the hose traffic model constraints. In addition to the guaranteed performance, deploying the VLB method in the AAPN network, eliminates signaling and replaces the dynamic core schedulers with static scheduler that can accommodate all tra�c matrices within the hose tra�c model boundaries

SDN-controlled and Orchestrated OPSquare DCN Enabling Automatic Network Slicing with Differentiated QoS Provisioning

In this work, we propose and experimentally assess the automatic and flexible NSs configurations of optical OPSquare DCN controlled and orchestrated by an extended SDN control plane for multi-tenant applications with differentiated QoS provisioning. Optical Flow Control (OFC) protocol has been developed to prevent packet losses at switch sides caused by packet contentions.Based on the collected resource topology of data plane, the optical network slices can be dynamically provisioned and automatically reconfigured by the SDN control plane. Meanwhile, experimental results validate that the priority assignment of application flows supplies dynamic QoS performance to various slices running applications with specific requirements in terms of packet loss and transmission latency. In addition, the capability of exposing traffic statistics information of data plane to SDN control plane enables the implementation of load balancing algorithms further improving the network performance with high QoS. No packet loss and less than 4.8 us server-to-server latency can be guaranteed for the sliced network with highest priority at a load of 0.5

AgileDCN:An Agile Reconfigurable Optical Data Center Network Architecture

This paper presents a detailed examination of a novel data center network (DCN) that can satisfy the high capacity and low latency requirements of modern cloud computing applications. This reconfigurable architecture called AgileDCN uses fast-switching optical components with a centralized control function and workload scheduler. By providing a highly flexible optical network fabric between server racks, very high network efficiencies can be achieved even under imbalanced loading patterns. Our simulation results show that, at high (70%) loads, TCP flow completion times in the AgileDCN are significantly lower than in an equivalent electronic leaf-spine network

Deploying SDN architecture in Open Optical Transport Networks

Pro udrženı́ tempa s rostoucı́mi požadavky na přenosovou rychlost, latenci a bezpečnost je nutné zvážit současnou koncepci řı́zenı́ sı́tı́. Software-Defined Networking (SDN) je jedno z možných řešenı́, ke kterému telekomunikačnı́ průmysl směruje. Tato práce představuje současný stav Software-Defined Networking a zaměřuje se na vybraná open-source řešenı́ v oblasti SDN kontrolerů, jako je ONOS či OpenDaylight. Hlavnı́m cı́lem této části práce je vysvětlit, jak může SDN pomoci vyřešit rostoucı́ požadavky na rozšı́řenı́ automatizace v otevřených optických sı́tı́ch. Praktická část této práce je rozdělená do dvou oblastı́. V rámci prvnı́ oblasti jsem se zabýval rozšı́řenı́m funkčnosti SDN kontroleru pro umožněnı́ konfigurace a řı́zenı́ optických komunikačnı́ch zařı́zenı́. Hlavnı́m přı́nosem je implementace nových funkcionalit SDN driveru pro Nokia 1830 PSS (ROADM) a rozšı́řenı́ funkcionality driveru pro Nokia 1830 PSI-2T (optický transpondér). Ve druhé části práce jsem se zabýval problematikou korelace alarmů v otevřených optických sı́tı́ch. Výsledkem je funkce pro korelaci alarmů ve formě SDN aplikace, kterou jsem dále otestoval na emulovaných optických zařı́zenı́ch pro prokázánı́ funkčnosti celého konceptu.With the rising demands on the network throughput, latency and security, legacy control networking concepts should be reconsidered. Software-Defined Networking (SDN) is one of the possible solutions, to which telecommunication industry is moving. This work presents current state-of-the-art in Software-Defined Networking and focuses on some open-source solutions of SDN controllers, like ONOS and OpenDaylight. Main focus is to understand how SDN can help to solve increasing demand for broader automation in Optical Transport Networks. The practical section is divided in two parts. Within the first part I focused on extending functionality of SDN controller to facilitate more efficient configuration and control of optical network devices. Main contribution was to implement additional features to SDN drivers for Nokia 1830 PSS (ROADM) and extend functionality of Nokia 1830 PSI-2T (Optical Transponder) driver. Second part is dedicated to the Alarm Correlation problematic in open optical networks. We designed, developed an Alarm Correlation function as a SDN application then we tested it on emulated optical devices to prove the concept

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

CONVERGED RACK ARCHITECTURE (CRA) FOR DATA CENTER

The data center hardware (HW) infrastructure in public and private clouds is going through a paradigm shift due to the demands of a heterogenous computing model. The lower-cost economics of a private cloud need to be augmented with the operational simplicity of a public cloud. The Open Compute Project (OCP) started with the goal of simplifying the compute aspect and they did succeed to some extent, but enterprise adoption has been slow due to the HW complexity of various elements and version compatibility. Since the evolution of OCP, a number of technology changes have occurred, and a new infrastructure standard is necessary to tackle the heterogenous computing model along with a thermal and high-speed input/output (I/O) interconnection nexus. Techniques are presented herein that support a converged rack architecture (CRA). Such an architecture encompasses a universal rack I/O paradigm comprising embedded opto-electrical data I/O posts, centralized power and cooling, and a common rack management unit (RMU) which allows a rack itself to be thought of as a compute unit where different compute, network, and storage components may be composed in a virtual domain on the fly and then decomposed when they are not required. In essence, a CRA manages and treats a rack frame as a complete converged system of compute, network, and storage elements and not as disparate entities

Bandwith allocation and scheduling in photonic networks

This thesis describes a framework for bandwidth allocation and scheduling in the Agile All-Photonic Network (AAPN). This framework is also applicable to any single-hop communication network with significant signalling delay (such as satellite-TDMA systems). Slot-by-slot scheduling approaches do not provide adequate performance for wide-area networks, so we focus on frame-based scheduling. We propose three novel fixed-length frame scheduling algorithms (Minimum Cost Search, Fair Matching and Minimum Rejection) and a feedback control system for stabilization.MCS is a greedy algorithm, which allocates time-slots sequentially using a cost function. This function is defined such that the time-slots with higher blocking probability are assigned first. MCS does not guarantee 100% throughput, thought it has a low blocking percentage. Our optimum scheduling approach is based on modifying the demand matrix such that the network resources are fully utilized, while the requests are optimally served. The Fair Matching Algorithm (FMA) uses the weighted max-min fairness criterion to achieve a fair share of resources amongst the connections in the network. When rejection is inevitable, FMA selects rejections such that the maximum percentage rejection experienced in the network is minimized. In another approach we formulate the rejection task as an optimization problem and propose the Minimum Rejection Algorithm (MRA), which minimizes total rejection. The minimum rejection problem is a special case of maximum flow problem. Due to the complexity of the algorithms that solve the max-flow problem we propose a heuristic algorithm with lower complexity.Scheduling in wide-area networks must be based on predictions of traffic demand and the resultant errors can lead to instability and unfairness. We design a feedback control system based on Smith's principle, which removes the destabilizing delays from the feedback loop by using a "loop cancelation" technique. The feedback control system we propose reduces the effect of prediction errors, increasing the speed of the response to sudden changes in traffic arrival rates and improving the fairness in the network through equalization of queue-lengths

Control plane routing in photonic networks

The work described in the thesis investigates the features of control plane functionality for routing wavelength paths to serve a set of sub-wavelength demands. The work takes account of routing problems only found in physical network layers, notably analogue transmission impairments. Much work exists on routing connections for dynamic Wavelength-Routed Optical Networks (WRON) and to demonstrate their advantages over static photonic networks. However, the question of how agile the WRON should be has not been addressed quantitatively. A categorization of switching speeds is extended, and compared with the reasons for requiring network agility. The increase of effective network capacity achieved with increased agility is quantified through new simulations. It is demonstrated that this benefit only occurs within a certain window of network fill; achievement of significant gain from a more-agile network may be prevented by the operator’s chosen tolerable blocking probability. The Wavelength Path Sharing (WPS) scheme uses semi-static wavelengths to form unidirectional photonic shared buses, reducing the need for photonic agility. Making WPS more practical, novel improved routing algorithms are proposed and evaluated for both execution time and performance, offering significant benefit in speed at modest cost in efficiency. Photonic viability is the question of whether a path that the control plane can configure will work with an acceptable bit error rate (BER) despite the physical transmission impairments encountered. It is shown that, although there is no single approach that is simple, quick to execute and generally applicable at this time, under stated conditions approximations may be made to achieve a general solution that will be fast enough to enable some applications of agility. The presented algorithms, analysis of optimal network agility and viability assessment approaches can be applied in the analysis and design of future photonic control planes and network architectures