Data Center Network Architecture Research Articles

An effective service-oriented networking management architecture for 5G-enabled internet of things

The development of a 5G-enabled Internet of Things has led to a dramatic increase in network traffic load, which has presented tremendous challenges to network management. In this paper, a service-oriented network architecture is proposed to support the effective management of 5G-enabled IoT systems. This architecture effectively reduces the traffic load and simplifies network management by introducing a service aggregation and caching (SAaC) scheme. Specifically, SAaC first breaks through the data-centric network architecture by converting data into services. Then, SAaC significantly reduces traffic load and energy consumption by service aggregation. Finally, SAaC introduces service caching, and each content router caches new services locally after aggregating received services so that user requests are handled at the network layer. Experimental results demonstrate that compared with traditional solutions, the SAaC scheme improves the request response time by 20.52%–56.09%, reduces the traffic load by 10.85%–37.67%, and reduces energy consumption by more than 50%.

SDN enabled flexible optical data center network with dynamic bandwidth allocation based on photonic integrated wavelength selective switch.

Optical switching techniques featuring the fast and large capacity have the potential to enable low latency and high throughput optical data center networks (DCN) to afford the rapid increasing of traffic-boosted applications. Flexibility of the DCN is of key importance to provide adaptive and dynamic bandwidth to handle the variable traffic patterns generated by the heterogeneous applications while optimizing the network resources. Aiming at providing the flexible bandwidth for optical DCNs, we propose and experimentally investigate a software-defined networking (SDN) enabled reconfigurable optical DCN architecture based on novel optical top of rack (OToR) switch exploiting photonic-integrated wavelength selective switch. Experimental results show that the optical bandwidth per link can be automatically reallocated under the management of the deployed SDN control plane according to the variable traffic patterns. With respect to the network with inflexible interconnections, the average packet loss of the reconfigurable DCN decreases 1 order of magnitude and the server-to-server latency performance improves of 42.2%. Scalability investigation illustrates limited (11.7%) performance degradation as the reconfigurable network scale from 2560 to 40960 servers. Both the numerical and experimental assessments validate the proposed DCN with reconfigurable bandwidth feature and lower latency variations with respect to the inflexible DCNs.

Open and disaggregated optical transport networks for data center interconnects [Invited

In this paper, we present Alibaba’s practices and views on open and disaggregated optical transport networks, with a focus on metro data center interconnects (DCIs). We first discuss technology developments that have enabled open optical transport networks, followed by a presentation of our open optical network architecture for DCI networks. We then describe an overall data center network architecture and the application scenario of open and disaggregated DCI technology. Details of the point-to-point DCI network architecture and the need for reconfigurable optical add–drop multiplexers (ROADMs) in DCI networks are then discussed. We present the data models of DCI equipment, including optical terminal transponders, point-to-point optical line systems, and ROADMs, developed based on OpenConfig YANG models. The detailed design and implementation of a home-grown control and management software platform for DCI networks are also presented. We conclude with a discussion of the real deployment of the technology in Alibaba’s networks.

Distributed Traffic Flow Consolidation for Power Efficiency of Large-Scale Data Center Network

Power optimization for data center networks (DCNs) has recently received increasing research attention, since a DCN can account for 10 to 20 percent of the total power consumption of a data center. An effective power-saving approach for DCNs is traffic consolidation, which consolidates traffic flows onto a small set of links and switches such that unused network devices can be shut down dynamically for power savings. While this approach has shown great promise, existing solutions are mostly centralized and do not scale well for large-scale DCNs. In this article, we propose DISCO, a <b><u>DIS</u></b> tributed traffic flow <b><u>CO</u></b> nsolidation framework, with correlation analysis and delay constraints, for large-scale data center network. DISCO features two distributed traffic consolidation algorithms that provide different trade-offs (as desired by different DCN architectures) between scalability, power savings, and network performance. First, a flow-based algorithm is proposed to conduct consolidation for each flow individually, with greatly improved scalability. Second, an even more scalable switch-based algorithm is proposed to consolidate flows on each individual switch in a distributed fashion. We evaluate the DISCO algorithms both on a hardware testbed and in large-scale simulations with real DCN traces. The results show that, compared with state-of-the-art centralized solutions, DISCO can achieve nearly the same power savings while decomposing the global problem into sub-problems that are three orders of magnitude smaller. As a result, DISCO can run <inline-formula><tex-math notation="LaTeX">$\mathbf {10^4}$</tex-math></inline-formula> to <inline-formula><tex-math notation="LaTeX">$\mathbf {10^6}$</tex-math></inline-formula> times faster for a DCN at the scale of 10K servers. The convergence of DISCO has also been proven theoretically and examined experimentally.

Constructing node-independent spanning trees on the line graph of the hypercube by an independent forest scheme

Due to the application in reliable communication, reliable broadcasting, secure message distribution, etc., node/edge-independent spanning trees (ISTs) have attracted much attention in the past twenty years. However, node/edge conjecture is still open for networks with node/edge-connectivity ≥ 5. So far, results have been obtained on a lot of special networks, but only a few results are reported on the line graphs of them. Hypercubes play important roles in parallel computing systems, and the line graphs of which have been recently adopted for the architectures of data center networks. Since the line graph of n-dimensional hypercube Qn, L(Qn), is (2n−2)-regular, whether there exist 2n−2 node-ISTs rooted at any node on L(Qn) is an open question. In this paper, we focus on the problem of constructing node-ISTs on L(Qn). Firstly, we point out that L(Qn) can be partitioned into 2n−1 complete graphs. Then, based on the complete graphs and n−1 node-ISTs rooted at 0 on Qn−10, we obtain an “independent forest” containing 2n−2 trees on L(Qn). Furthermore, we present an O(N) time algorithm to construct 2n−2 node-ISTs rooted at node [0, 2n−1] isomorphic to each other on L(Qn) based on the independent forest, where N=n×2n−1 is the number of nodes on L(Qn). In addition, we point out that the 2n−2 node-ISTs on L(Qn) is a new method to prove the node/edge-connectivity and the upper bound of (2n−2)-node/edge-wide-diameter of L(Qn).

Crystal: A scalable and fault-tolerant Archimedean-based server-centric cloud data center network architecture

The explosive increase in adopting cloud services leads to the need for accommodating millions to even billions of servers in the supporting infrastructure of data center networks. Thus, providing highly scalable and noticeably fault-tolerant interconnecting architectures with great network capacity, limited delay, and reasonable energy consumption has become of paramount importance. In this paper, Crystal, a server-centric and recursively constructed structure, is presented. Crystal is made out of building blocks inspired by vertex configuration pattern of Archimedean solids and is intrinsically fault-tolerant mainly due to the adoption of multihoming mechanism in the building block. Crystal also scales double exponentially owing to its recursively defined architecture. Furthermore, to increase the routing efficiency and manage different kinds of failures in the network, two exclusively designed routing algorithms are proposed. Theoretical analysis and simulation results all witness that Crystal is highly fault-tolerant and can provide good network capacity and low latency to support delay-sensitive and data-intensive applications. Generally, Crystal satisfies a reasonable trade-off between all the major goals of designing a cloud data center network.

TIO: A VLC-enabled hybrid data center network architecture

To satisfy the ever-increasing bandwidth demand of modern data centers, researchers have proposed hybrid Data Center Networks (DCNs), which employ high-bandwidth Optical Circuit Switches (OCSs) to compensate for Electrical Packet Switches (EPS). Existing designs, such as Helios and c-Through, mainly focus on reconfiguring optical devices to meet the estimated traffic requirements. However, these designs face two major challenges in their OCS-based networks, namely, the complex control mechanism and cabling problems. To solve these challenges, we propose TIO, a hybrid DCN that employs Visible Light Communication (VLC) instead of wired OCS design to connect racks. TIO integrates the wireless VLC-based Jellyfish and wired EPS-based Fat Tree seamlessly and combines the opposite and complementary characteristics, including wireless VLC direct connection and wired electrical packet switching, random graph, and Clos topology properties. To further exploit the merits of TIO, we design a hybrid routing scheme and congestion-aware flow scheduling method. Comprehensive evaluations indicate that TIO outperforms the Jellyfish and Fat Tree in both topology properties and network performance, and the flow scheduling method also evidently improves performance.

NBP: Namespace-based privacy to counter timing-based attack in named data networking

NDN is one of the most prominent candidates for the future network. It has a data-centric network architecture in which fetching of content, forwarding requests, and routing is done through the name of the content. Content caching is an essential feature in NDN as its performance depends upon its efficiency of caching contents. Cache in NDN is open for all types of requesters. An attacker can probe an interest packet and find out whether the content corresponding to the interest packet is cached or not by observing the time difference between the timestamps at which the content is received and the request is sent. This attack is called timing-based attack (TBA). Existing solutions for TBA are based on securing individual contents. Therefore, they use large size table, which have data related to each content. Managing these large tables is expensive in terms of space and time. Also, the existing approaches fail to mitigate TBA or can be attacked by the attacker. To counter these limitations a Namespace-Based Privacy (NBP) approach has been proposed for content generation and handling its privacy. Additionally, an approach is proposed which detects the attack pattern at the gateway router itself and triggers the countermeasure in case of attack. The results prove that the proposed approach is better than the existing eminent approaches.

HSDC: A Highly Scalable Data Center Network Architecture for Greater Incremental Scalability

As the volume of data keeps growing rapidly, more and more storage devices, servers and network devices are continuously added into data centers to store, manage and analyze the data. The industry experience indicates that, instead of a huge number of servers added at a time, the data center network also expands gradually by adding a small number of servers from time to time. As a result, how to achieve an incremental scalability is becoming a very important challenge in designing modern data center network architectures in order to maintain the topological properties unchanged when the size of data centers grows. In this paper, we propose a new type of data center network architecture named HSDC (High Scalability Data Center Network Architecture) based on the hypercube network. The HSDC is constructed by using $m$m-port switches and 2-port servers. The fault-tolerant routing algorithm designed in this paper for HSDC can be executed on any vertex and is able to construct a path between any pair of vertices. In order to achieve an incremental scalability, we further propose three types of incomplete HSDC structures that allow gradually adding servers into the structures, while maintaining all the topological properties. The simulation experiments and performance results demonstrate that the throughput of HSDC is comparable to that of Fat-Tree, BCube and DCell. Furthermore, the analysis results indicate that HSDC strikes a good balance among diameter, bisection width, incremental scalability, cost and energy consumption in contrast to the state-of-the-art data center network architectures.

DCnet: a data centre network architecture that supports live VM migration

Cloud computing and storage have become an integral part of online Internet services. Over the past decade, enterprises have steadily moved their applications and storage to the cloud paradigm. Server virtualisation enables cloud providers to utilise computational resources efficiently by employing virtual machines (VMs) and containers. As more enterprise applications are hosted by VMs in the cloud, a significant amount of network communication occurs among servers within a data centre, increasing so-called ‘ east-west communication’ . In addition to scaling to accommodate more east-west traffic, future data centre networks must support efficient VM migration, which is used to optimise power consumption. This article proposes a new data centre network architecture called DCnet . DCnet changes addressing and routing at layers 2 and 3 completely to increase throughput and support live VM migration throughout an organisation, including across multiple data centres owned by an organisation that spans large geographic areas. DCnet retains compatibility with existing hardware by using the same frame format as standard protocols, specifically Ethernet and Internet protocol (IP). Furthermore, DCnet does not require any changes to applications and host operating systems or libraries. In addition to presenting the architecture, the article describes a test bed used to assess DCnet and reports experimental measurements.

An Efficient Wireless Control Plane for Software Defined Networking in Data Center Networks

Software defined networking (SDN) has re-defined the way data center networks are deployed and functioned. The ability to separate the control plane and data plane have led to the simpler design and easier management. In SDN, the data plane and control plane are separately managed, so building an additional wired network to connect the control plane and the data plane can lead to a high cabling complexity. This paper proposes an end-to-end end wireless control plane architecture for SDN-enabled data center networks. In the proposed architecture, the switches form clusters that are wirelessly connected to the controller via access points (APs) and relay nodes (RNs). The switches use the 2.4/5-GHz band to connect with the APs, whereas the APs and the RNs are connected to the controller using the 60-GHz band. We have presented an analytical model to derive achievable data rates in our wireless control plane. We have also proposed two algorithms that allow an optimal number of a cluster size of the switches to be connected with the Controller via minimum number to APs/RNs such that the control traffic demands of the switches is guaranteed in interference constrained environment. Through extensive simulations, the results of our proposed architecture show that the cabling complexity in the control plane is reduced to zero and additional switches may be easily added in SDN data center. Thus, a pure wireless solution for building a control plane in a data center network is feasible.

Hybrid OCS/OBS interconnect in intra-data-center network

We report on a data center network (DCN) architecture based on hybrid optical circuit switching (OCS) and optical burst switching (OBS) interconnect for dynamic DCN connectivity provisioning. With the combination of the centralized and distributed control of the software-defined optical networks, the proposed interconnect can achieve unprecedented flexibility in dealing with both mice and elephant flow in the DCN. Numerical simulation is employed to investigate the performance of the proposed architecture. The results show that the OBS module has preferable performance in dealing with a larger burst packet, and the throughput is constrained by the capacity of the server random access memory module.

Performance Evaluation of a Power-Efficient and Robust 60 GHz Wireless Server-to-Server Datacenter Network

Datacenters have become the digital backbone of the modern world. To support the growing demands on bandwidth, datacenter networks (DCNs) consume an increasing amount of power. Additionally, the complex cabling in traditional datacenters poses design and maintenance challenges and increases the energy cost of the cooling infrastructure by obstructing the flow of chilled air. In this paper, we present a wireless server-to-server datacenter network architecture using millimeter-wave links to eliminate the need for power-hungry switching fabric of traditional fat-tree based datacenter networks. The server-to-server wireless datacenter network (S2S-WiDCN) architecture requires line-of-sight (LoS) between servers to establish direct communication links. However, in the presence of an obstruction such as an IT technician, the LoS may be blocked. To address this issue, we propose a novel obstruction-aware adaptive routing algorithm for S2S-WiDCN. We evaluate the performance of S2S-WiDCN in terms of traffic flow completion duration and throughput, with different kinds of datacenter traffic as well as in presence of obstruction to LoS links. We also compare the performance and power efficiency of S2S-WiDCN with the traditional fat tree DCN as well as a top-of-rack (ToR)-to-ToR wireless DCN.

Effectively Reconfigure the Optical Circuit Switching Layer Topology in Data Center Network by OCBridge

All optical or hybrid electrical/optical switching data center network (DCN) architectures are capable of adapting the optical-layer topology to various network traffic demands based on the flexibility of optical switching technology. The topology reconfiguration strategies in previous research simply attempt to reconfigure optical circuit switching (OCS) links to offload heavier rack-to-rack traffic. However, due to the complex multi-layer interconnections and the various network traffic patterns in DCNs, the OCS links will not only offload the network traffic between its source and destination racks, but also forward the network traffic that belongs to the adjacent racks of the source and destinations racks. Previous strategies ignore the forwarding traffic and result in sub-optimal solutions. In order to overcome the shortcomings of previous methods and make full use of the OCS link resources in DCNs, an effective topology reconfiguration strategy named optical circuit bridge (OCBridge) has been proposed in our recent work. The main idea of our OCBridge is to take into account the traffic demands between the source and destination regions of each OCS link. In this paper, we first review our OCBridge, and then in simulation, we evaluate the performance of our OCBridge by testing it in two typical OCS-based DCNs, including OpenScale and Helios. Under our OCBridge, we analyze the outstanding network throughput performance of the DCNs and investigate the communication distance of traffic demands. Finally, in experiment, we deploy our OCBridge to a small prototype of OpenScale and verify that our OCBridge is capable of accelerating the distributed computing applications compared with previous topology reconfiguration strategies.

SVDC: A Highly Scalable Isolation Architecture for Virtualized Layer-2 Data Center Networks

While large layer-2 networks are widely accepted as the network fabric for modern data centers and network virtualization is required to support multi-tenant cloud computing, existing network virtualization solutions are not specifically designed for layer-2 networks. In this paper, we design SVDC , a highly-scalable and low-overhead virtualization architecture for large layer-2 data center networks. By leveraging the emerging software defined networking (SDN) framework, SVDC decouples the global identifier of a virtual network from the identifier carried in the packet header. Hence, SVDC can scale to a great number of virtual networks with a very short tag in the packet header, which is never achieved by previous network virtualization solutions. SVDC enhances MAC-in-MAC encapsulation in a way that packets with overlapped MAC addresses are correctly forwarded even without in-packet global identifiers to differentiate the virtual networks they belong to. Besides, scalable and efficient layer-2 multicast and broadcast within virtual networks are also supported in SVDC. With extensive simulations and experiments, we show that SVDC is better than existing solutions in many aspects, particularly isolating virtual networks with high scalability and higher network goodput due to minimal packet header overhead.

Load Balance in Data Center SDN Networks

&lt;span&gt;In the last two decades, networks had been changed according to the rapid changing in its requirements. The current Data Center Networks have large number of hosts (tens or thousands) with special needs of bandwidth as the cloud network and the multimedia content computing is increased. The conventional Data Center Networks (DCNs) are highlighted by the increased number of users and bandwidth requirements which in turn have many implementation limitations. The current networking devices with its control and forwarding planes coupling result in network architectures are not suitable for dynamic computing and storage needs. Software Defined networking (SDN) is introduced to change this notion of traditional networks by decoupling control and forwarding planes. So, due to the rapid increase in the number of applications, websites, storage space, and some of the network resources are being underutilized due to static routing mechanisms. To overcome these limitations, a Software Defined Network based Openflow Data Center network architecture is used to obtain better performance parameters and implementing traffic load balancing function. The load balancing distributes the traffic requests over the connected servers, to diminish network congestions, and reduce underutilization problem of servers. As a result, SDN is developed to afford more effective configuration, enhanced performance, and more flexibility to deal with huge network designs&lt;/span&gt;

Photonic-Frame-Based TCP proxy architecture in optically interconnected data center networks

Optical switching is a good candidate for achieving the key requirements of high scalability, low latency and low power consumption in future large-scale data center networks (DCNs). However, circuit-based optical switching has a disadvantage of a long reconfiguration time. Packet-based optical switching also faces challenges such as the complexity of optical header processing and the difficulty of buffering in optical switches to resolve contention. To address these problems, we present a packet-switched optical network architecture design with a photonic frame wrapper that can generate variable-size photonic frames for optically interconnected intra-DCN. The proposed architecture forms hybrid DCN architecture consisting of a flattened optical switch layer for the data path and a conventional electrical switch layer for the control path. The photonic frame wrapper can increase bandwidth utilization by minimizing guard-time insertion in the optical switch domain. We also introduce a photonic frame wrapper with proxy solution to fully exploit the gain of the proposed architecture even in inter-DCN communication with long delays, which is compliant with standard TCP instances at end nodes. In intra-DCN, the average queuing delay is analyzed to find the efficient combinations between the guard time and time-slot length for the variable-sized photonic frame. We also analyzed the bandwidth overhead of guard time, to show it is comparable to that of Ethernet based DCN. In inter-DCN, the proxy solution demonstrates a noticeable TCP performance enhancement compared with the photonic frame wrapper in terms of bandwidth efficiency and end-to-end delay by theoretical and OPNET simulation analyses.

Free Space Intra-Datacenter Interconnects Based on 2D Optical Beam Steering Enabled by Photonic Integrated Circuits

Data centers are continuously growing in scale and can contain more than one million servers spreading across thousands of racks; requiring a large-scale switching network to provide broadband and reconfigurable interconnections of low latency. Traditional data center network architectures, through the use of electrical packet switches in a multi-tier topology, has fundamental weaknesses such as oversubscription and cabling complexity. Wireless intra-data center interconnection solutions have been proposed to deal with the cabling problem and can simultaneously address the over-provisioning problem by offering efficient topology re-configurability. In this work we introduce a novel free space optical interconnect solution for intra-data center networks that utilizes 2D optical beam steering for the transmitter, and high bandwidth wide-area photodiode arrays for the receiver. This new breed of free space optical interconnects can be developed on a photonic integrated circuit; offering ns switching at sub-μW consumption. The proposed interconnects together with a networking architecture that is suitable for utilizing those devices could support next generation intra-data center networks, fulfilling the requirements of seamless operation, high connectivity, and agility in terms of the reconfiguration time.

A cost-effective low-latency overlaid torus-based data center network architecture

In this paper, we present the design, analysis, and implementation of a novel data center network architecture named CLOT, which delivers significant reduction in the network diameter, network latency, and infrastructure cost. CLOT is built based on a switchless torus topology by adding only a number of most beneficial low-end switches in a proper way. Forming the servers in close proximity of each other in torus topology well implements the network locality. The extra layer of switches largely shortens the average routing path length of torus network, which increases the communication efficiency. We show that CLOT can achieve lower latency, smaller routing path length, higher bisection bandwidth and throughput, and better fault tolerance compared to both conventional hierarchical data center networks as well as the recently proposed CamCube network. Coupled with the coordinate based geographical addresses and credit based flow control, the specially designed POW routing algorithm helps CLOT achieve its maximum theoretical performance. Besides, an automatic address configuration mechanism and malfunction detection mechanism are provided to facilitate the network deployment and configuration. The sufficient mathematical analysis and theoretical derivation prove both guaranteed and ideal performance of CLOT.

Evaluation Study of a Proposed Hadoop for Data Center Networks Incorporating Optical Circuit Switches

Hybrid data center network architectures, which combine electrical packet switches (EPSs) with optical circuit switches (OCSs), have been proposed to handle the inter-rack link oversubscription problem in a cost- and power-efficient manner. However, the high reconfiguration delay of optical switching technologies makes it challenging to effectively leverage OCSs in these hybrid networks. In our prior work, we proposed a modified version of Hadoop, called Hadoop for hybrid networks (HHN), to create network traffic patterns that match the characteristics of OCSs. This paper presents a comprehensive comparative evaluation of HHN on hybrid networks and the original Hadoop on conventional EPS-only networks. Numerical results validate our hypothesis that it is feasible to achieve similar system-level and user-level performance with HHN while simultaneously achieving power and cost savings with the hybrid network. When the percentage of shuffle- heavy (SH) jobs is small, e.g., 5%, HHN performance is the same as that of the original Hadoop on an EPS-only network. When the percentage of SH jobs is large, e.g., 20%, the HHN performance is almost the same even at high loads, and even with a smaller number of input-block replicas when we placed an upper bound on the per-job input-data size. For large SH jobs with input-data sizes larger than the upper bound, the performance of HHN could be improved significantly when storing a larger number of replicas for each input block.