Disaster-Resilient Control Plane Design and Mapping in Software-Defined Networks

Communication networks, such as core optical networks, heavily depend on their physical infrastructure, and hence they are vulnerable to man-made disasters, such as Electromagnetic Pulse (EMP) or Weapons of Mass Destruction (WMD) attacks, as well as to natural disasters. Large-scale disasters may cause huge data loss and connectivity disruption in these networks. As our dependence on network services increases, the need for novel survivability methods to mitigate the effects of disasters on communication networks becomes a major concern. Software-Defined Networking (SDN), by centralizing control logic and separating it from physical equipment, facilitates network programmability and opens up new ways to design disaster-resilient networks. On the other hand, to fully exploit the potential of SDN, along with data-plane survivability, we also need to design the control plane to be resilient enough to survive network failures caused by disasters. Several distributed SDN controller architectures have been proposed to mitigate the risks of overload and failure, but they are optimized for limited faults without addressing the extent of large-scale disaster failures. For disaster resiliency of the control plane, we propose to design it as a virtual network, which can be solved using Virtual Network Mapping techniques. We select appropriate mapping of the controllers over the physical network such that the connectivity among the controllers (controller-to-controller) and between the switches to the controllers (switch-to-controllers) is not compromised by physical infrastructure failures caused by disasters. We formally model this disaster-aware control-plane design and mapping problem, and demonstrate a significant reduction in the disruption of controller-to-controller and switch-to-controller communication channels using our approach.Comment: 6 page

Bandwidth provisioning for virtual machine migration in cloud: Strategy and application

Physical resources are highly virtualized in todays datacenter-based cloud-computing networks. Servers, for example, are virtualized as Virtual Machines (VMs). Through abstraction of physical resources, server virtualization enables migration of VMs over the interconnecting network. VM migration can be used for load balancing, energy conservation, disaster protection, etc. Migration of a VM involves iterative memory copy and network re-configuration. Memory states are transferred in multiple phases to keep the VM alive during the migration process, with a small downtime for switchover. Significant network resources are consumed during this process. Migration also results in undesirable performance impacts. Suboptimal network bandwidth assignment, inaccurate pre-copy iterations, and high end-to-end network delay in wide-area networks (WAN) can exacerbate the performance degradation. In this study, we devise strategies to find suitable bandwidth and pre-copy iteration count to optimize different performance metrics of VM migration over a WAN. First, we formulate models to measure network resource consumption, migration duration, and migration downtime. Then, we propose a strategy to determine appropriate migration bandwidth and number of pre-copy iterations, and perform numerical experiments in multiple cloud environments with large number of migration requests. Results show that our approach consumes less network resources when compared with maximum and minimum-bandwidth provisioning strategies while using an order of magnitude less bandwidth than maximum-bandwidth strategy. It also achieves significantly lower migration duration than minimum-bandwidth scheme

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42\ub74% vs 44\ub72%; absolute difference \u20131\ub769 [\u20139\ub758 to 6\ub711] p=0\ub767; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5\u20138] vs 6 [5\u20138] cm H2O; p=0\ub70011). ICU mortality was higher in MICs than in HICs (30\ub75% vs 19\ub79%; p=0\ub70004; adjusted effect 16\ub741% [95% CI 9\ub752\u201323\ub752]; p<0\ub70001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0\ub780 [95% CI 0\ub775\u20130\ub786]; p<0\ub70001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status. Funding: No funding

Signalling Cost Analysis of SINEMO: Seamless End-to-End Network Mobility ∗ ABSTRACT Abu S Reaz,

IETF has proposed Mobile IPv6-based Network Mobility (NEMO) basic support protocol (BSP) to support network mobility. NEMO BSP inherits all the drawbacks of Mobile IPv6, such as inefficient routing path, single point of failure, high handover latency and packet loss, and high packet overhead. To address these drawbacks, we proposed an IP diversity-based network mobility management scheme called Seamless IP-diversity based NEtwork MObility (SINEMO). In this paper, we develop an analytical model to analyze and compare the signalling costs of SINEMO and and NEMO BSP. Our analysis shows that SINEMO reduces the signalling cost by a factor of two when compared to NEMO BSP

Performance of End-to-End Mobility Management in Satellite IP Networks

Abstract — IETF has developed Mobile IP to support mobility of IP hosts at the network layer. The National Aeronautics and Space Administration has implemented Mobile IP to handle handovers in space networks. Due to a number of limitations of Mobile IP, such as high handover latency, packet loss rate, and conflict with existing network security solutions, a new IPdiversity based mobility management scheme, called SIGMA, has been developed through collaborative efforts of NASA and University of Oklahoma. In this paper, we illustrate the performance of SIGMA for managing handovers in space networks. We show by simulation that SIGMA extends network connectivity from space to ground, and ensures smooth handover between spacecrafts for different space network scenarios. I

SINEMO: An IP-diversity based approach for network mobility in space

IETF proposed Network Mobility (NEMO) Basic Support Protocol (BSP) to support network mobility. NEMO BSP is an extension of Mobile IP v6 (MIPv6), and inherits all the drawbacks of MIPv6 (like inefficient routing, high handover latency and packet loss rate). Satellites equipped with several IP-enabled devices is an example of network mobility in space networks. In this paper, we propose an IP-diversity based network mobility architecture called SINEMO, and show that SINEMO can exhibit better performance than NEMO BSP in satellite IP networks. 1

Handover Schemes in Space Networks: Classification and Performance Comparison ∗

Third Generation (3G) communication networks based on Low Earth Orbit (LEO) satellites provide a new trend in future mobile communications. LEO satellites provide lower end-to-end delays and efficient frequency spectrum utilization, making it suitable for Personal Communication Services (PCS). However, ongoing communications using LEO satellite systems experience frequent handover due to high rotational speed of satellites. In this paper, we provide a comprehensive literature survey on proposed handover schemes for LEO satellite systems. We also present a detailed classification of handover schemes in the literature. Finally, we compare the handover schemes using different Quality of Service. 1

Performance Analysis of SINEMO: Seamless IP-diversity based Network Mobility

Abstract — IETF has proposed Mobile IPv6-based Network Mobility (NEMO) basic support protocol (BSP) to support network mobility. NEMO BSP inherits all the drawbacks of Mobile IPv6, such as inefficient routing path, single point of failure, high handover latency and packet loss, and high packet overhead. To address these drawbacks, we proposed an IP diversity-based network mobility management scheme called Seamless IP-diversity based NEtwork MObility (SINEMO). In this paper, we develop analytical models to analyze and compare the performance of SINEMO and NEMO BSP. Our analysis shows that SINEMO enhances the performance of network mobililty compared to NEMO BSP. We have implemented a testbed for SINEMO to support our claim of SINEMO’s high performance. I