Hot Potato Research Articles

Lewis Carroll and the Red Hot Potato: A graph theoretic approach to a linear algebraic identity

The Lewis Carroll Identity expresses the determinant of a matrix in terms of subdeterminants obtained by deleting one row and column or a pair of rows and columns. Using the matrix tree theorem, we can convert this into an equivalent identity involving sums over pairs of forests. Unlike the Lewis Carroll Identity, the Forest Identity involves no minus signs. In 2011, Vlasev and Yeats (2012) suggested that such a Forest Identity could be proven using edge transfers similar to Zeilberger’s 1997 matrix proof. However, until now, such an algorithm has not yet been developed. In this paper, we provide this edge transfer algorithm and a bijective proof for both the Lewis Carroll Identity and Forest Identity. This bijection is implemented by the Red Hot Potato algorithm, so called because the way edges get tossed back and forth between the two forests is reminiscent of the children’s game of hot potato.

Agroforestry as a sustainable means to farmer–grazier conflict mitigation in Cameroon

Farmer–grazier conflicts are a major cause of the stagnated development experienced in rural, peri-urban, and suburban areas across Africa and the developing world, as these conflicts often lead to the loss of crops, livestock, and even human lives, precipitating untold misery and excruciating poverty. In Cameroon where this study was undertaken, the situation is simply pathetic as farmer–grazier conflicts occur regularly, especially during the dry season when herders move livestock (especially cattle, sheep and horses) from hills to the valleys (transhumance), in search of pasture, destroying farmers’ crops in the process. It is within this framework that this study sought to look at the contribution of agroforestry practices to farmer–grazier conflict mitigation. Data collection methods for the study were household surveys, key informant interviews and direct observations. Data analysis was done through descriptive and inferential statistics, using two main statistical analyses software: Microsoft Excel 2007 and SPSS 20. Findings revealed that the main cause of farmer–grazier conflicts was limited arable and grazing land (100%), with the main consequences being loss of human lives and crops/livestock (100%). The main agroforestry practices of farmers were home gardens with animals (52%), trees on croplands (60%) and live fences/hedges (52%) while graziers’ agroforestry practices were home gardens with animals (73%), trees on grazing lands (60%) and live fences/hedges (53%). Agroforestry was found to provide many socio-economic and ecosystem benefits to both farmers and graziers like food, fuelwood, fodder, building materials and shade which make farmers and graziers less interdependent. Correlation analysis revealed a strong inverse relationship between the practice of agroforestry and farmer–grazier conflicts (p < 0.01). Chi square test statistic showed a significant relationship between agroforestry practices and farmer–grazier conflicts (p < 0.01). Parameter estimates of the Binary Logistic Regression model revealed that three main agroforestry practices (home garden with animals, trees on crop/grazing lands and home garden) were determinant in mitigating farmer–grazier-conflicts (p < 0.01). This clearly demonstrates that the practice of agroforestry can contribute in a sustainable way to end recurrent farmer–grazier conflicts. The study therefore recommends that more attention be directed towards agroforestry by policy makers and other stakeholders who seek to mitigate the farmer–grazier conflict hot potato.

The Effects of Pretreatment Methods on Quality Characteristic of Hot Air-dried Sweet Potato Slices

In this study, the effects of heat-moisture treatment (boiling or steaming for 45 min) prior to hot air drying (70℃ for 8 h) on water activity (Aw), moisture (MC), Brix, color, and texture of dried sweet potato slices were investigated to identify the best pretreatment condition for producing dried sweet potato with the best eating quality. Dried sweet potato slices pretreated by boiling (BL) showed significantly lower Aw, MC, and hardness while Brix was significantly higher than with steaming (ST) treatment. There were no significant differences for the color, springiness, cohesiveness, gumminess, and brittleness indexes. At 8 h drying, the Aw, MC, Brix, and hardness of the BL and ST samples were 0.81 and 0.82, 19.71% and 25.53%, 53.80% and 49.40%, and 20.49 kg/cm2 and 31.98 kg/cm2, respectively. This information will be useful for manufacturers in the production of dried sweet potato slices. These findings provide evidence of the feasibility of heat-moisture treatments in the production of dried sweet potato.

Microbiome Composition and Relationships Among Glycemic Responses Following Resistant Starch Intake from Potatoes

Abstract Objectives We explored the relationship between microbiome α-diversity and relative abundance (RA) of resistant starch (RS)-degrading bacteria and glycemic responses following the intake of Russet potatoes with varying amounts of RS. Methods Healthy females who were overweight consumed 250gm of hot (∼8.5 gm RS) or cold potatoes (∼10.8 gm RS) in a randomized crossover study. Stool was collected prior to the intervention and microbiomes were profiled using 16S rRNA gene sequencing. Only bacterial genera prevalent in ≥ 50% of subjects were included. Diet journals were collected for 10 days. Participants had postprandial blood drawn at 15, 30, 60, &amp; 120 min following the potatoes for glucose, insulin, glucose-dependent insulinotropic peptide (GIP), and glucagon-like peptide-1 (GLP-1) analysis. “Responders” to RS were those with a ≥ 20% reduction (mean % difference) in area under the curve (AUC) of insulin following cold vs hot potatoes. Insulin was chosen because it had the most pronounced change among the biomarkers. Spearman's correlation identified relationships between bacteria and the diet and glycemic responses. Wilcoxon signed rank test compared data between Responder groups. Linear mixed models assessed glycemic responses over time. Results Thirty subjects (29.6 ± 6.0 y, BMI 32.8 ± 3.7 kg/m2) completed the study. There were significant reductions in AUC insulin and GIP across the interventions following the cold potato compared to the hot potato: P = 0.012, partial ŋ2 = 0.213 (insulin) and P &amp;lt; 0.0001, partial ŋ2 = 0.875 (GIP). No differences in glucose or GLP-1 were found. Shannon α-diversity score negatively correlated with mean dietary fat (r = -0.776, P &amp;lt; 0.0001) and positively correlated with % kilocalories from carbohydrates and insoluble fiber (r = 0.568, P = 0.001 &amp; r = 0.527, P = 0.003, respectively). Responders (59%) to increased RS intake only differed in the RA of Subdoligranulum (P = 0.011), a butyrate-producing bacterium. Conclusions Most participants responded to RS resulting in lower AUC insulin. Several Ruminococcaceae genera correlated with AUC GIP or GLP-1 following both potatoes, which may glean insight on potential mechanisms that affect insulin response following cold or hot potatoes with varying amounts of RS. Funding Sources The Alliance for Potato Research and Education and the university's Small Grant Program.

Our sea: Music therapy in dementia and end-of-life care in the Mediterranean region

Our sea: Music therapy in dementia and end-of-life care in the Mediterranean region

Fingerprint-related chaotic image encryption scheme based on blockchain framework

Chaotic image encryption has been greatly investigated in recent years. However, a considerable number of the encryption schemes had been cracked by chosen plaintext attack (CPA). Although the new proposed plaintext-related chaotic image encryption schemes can resist CPA effectively, the emerged key management problem is a hot potato. In this paper, a novel fingerprint-related chaotic image encryption scheme is proposed. The generation of key streams is affected by the fingerprints of distributors rather than the plaintexts of images. In addition, the blockchain framework is adopted to ensure that the encrypted image was sent correctly form the distributor. Moreover, the distributors’ fingerprints embedded in the encrypted images are encoded by the anti-collusion code in order to record multiple fingerprints with fixed length of data. The proposed method has the following superiorities: 1) Security. CPA is invalid because the attacker does not have the fingerprint of the legal receiver. Meanwhile, no key management problem is caused. 2) Authenticity. The image, the sender and the receiver are all verified by using blockchain framework. 3) Traceability. All distributors’ fingerprints can be extracted correctly from the merged fingerprint based on the anti-collusion code, and the transmission of the image can be traced.

Novel and Noteworthy Aspects of Australia’s Recent Investment Agreements and ISDS Policy: The CPTPP, Hong Kong, Indonesia and Mauritius Transparency Treaties

Investment treaties, and especially investor-state dispute settlement (ISDS) provisions, became a political hot potato from around 2011 when Philip Morris brought the first-ever ISDS claim against Australia under an old bilateral investment treaty (BIT) with Hong Kong. A Labor-Greens Government declared that it would no longer agree to ISDS provisions in future treaties, but when a centre-right Coalition Government regained power from 2013 it reverted to concluding treaties containing ISDS clauses on a case-by-case assessment. Australia therefore agreed to ISDS in FTAs with Korea and China, but not bilaterally with Japan. However ISDS-backed provisions apply between Australia and Japan since the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP) can into force between them (and five other Asia-Pacific nations so far) from January 2019. Yet the Australian parliament engaged in robust debate about ratification of the CPTPP, with Labor Opposition (and Greens) parliamentarians continuing to voice concerns over ISDS provisions, despite the Philip Morris claim against Australia’s tobacco plain packaging having been rejected on jurisdictional grounds in 2015. This paper examines how (US-style) CPTPP drafting compares with two important recent investment agreements subsequently signed by Australia over 2019, namely with Indonesia as part of a wider free trade agreement (IA-CEPA), and with Hong Kong (AHKIA, alongside a bilateral FTA covering non-investment matters). AHKIA came into force from 17 January 2020, while IA-CEPA has been ratified by Australia but not yet by Indonesia. IA-CEPA adds a provision unique in the universe of over 3000 investment agreements world-wide, probably proposed by the Indonesian side: a compulsory mediation step prior to arbitration, if the host state requests mediation after the foreign investor initiates ISDS. The paper also highlights other features of both treaties that may help reduce delays and hence costs in ISDS. The paper summarises empirical data about delays and costs, as well as transparency around ISDS as another growing public concern, including some of our own empirical data provided as evidence to an Australian parliamentary inquiry into ratifying the CPTPP. We also examine the 2019 parliamentary inquiry that agreed with the submission that Australia should ratify the Mauritius (“UN ISDS”) Convention, thereby retrofitting extensive transparency provisions on pre-2014 treaties between Australia and other states that might also accede to that framework Convention. Even if Mauritius Convention ratifications proliferate, however, it will not retrofit extra transparency provisions to treaties concluded even after 1 April 2014 even among those states (say between Australia and Indonesia, where the investor chooses the ICSID Rules rather than UNCITRAL Rules option for arbitration). Accordingly, states ratifying the Mauritius Convention will still need to agree bilaterally to expand any still-limited transparency provisions in such post-2014 treaties, which is quite inefficient compared to a multilateral solution. Nonetheless, we conclude from these new developments that Australia is now better placed to play a more active role in guiding the future path of international investment treaty-making multilaterally and especially in the Asia-Pacific region.

How (Not) to Eat a Hot Potato

We consider a dynamic matching problem where players are repeatedly assignedtasks and can choose whether to accept or reject them. Players prefer to avoidcertain tasks (“hot potatoes”) while other tasks give a positive payoff (“sweet pota-toes”). There are frictions in the matching process in that players may not bematched to desirable tasks even if one is available. Both under the optimal mecha-nism and in decentralized settings, players may accept hot potatoes if this reducesfrictions in the matching process. We quantify the welfare loss due to matchingfrictions and show that, unlike losses due to more conventional frictions, it does notvanish when the cost of handling hot potatoes grows large.

Doing impact work while female: Hate tweets, ‘hot potatoes’ and having ‘enough of experts’

Drawing upon lived experiences, this article explores challenges facing feminist academics sharing work in the media, and the gendered, raced intersections of ‘being visible’ in digital cultures which enable direct, public response. We examine online backlash following publication of an article about representations of Meghan Markle’s feminism being co-opted by the patriarchal monarchy. While in it we argued against vilification of Markle, we encountered what we term distortions of research remediation as news outlets reported our work under headlines such as ‘academics accuse Meghan of dropping feminism like a hot potato’. Negative responses were polarised: anti-Meghan (drawing upon racist, anti-feminist, pro-empire, pro-Brexit/Trump rhetoric), and pro-Meghan (both general royal enthusiasts, and a smaller subsection viewing Markle in terms of politicised black uplift). In response, we received accusations of sexist, racist bullying, debate over definitions of feminism, claims feminism has gone ‘too far’, variously worded directives to ‘shut up’, gendered personal insults, and threats of doxxing. This article examines the tenor of public discourse around feminism and visible feminists. It questions the responsibility of institutions benefiting from public intellectuals for the wellbeing of employees in the public eye, particularly in the anti-intellectual socio-political context of Brexit and Donald Trump, where the costs for ‘visible’ women and feminist activism are ever higher. It also considers our responsibility as researchers to ensure our contributions to public discourse do not exacerbate existing harms of a white-supremacist, classist society. This article interrogates the risks – of misrepresentation, hyper-visibility, and reputational, psychological and potentially physical harm – faced by those engaging in acts of public feminism.

Let's Play Hot Potato! Controversial Topics in the Pharmacopalliation of Serious Illness (P03)

Let's Play Hot Potato! Controversial Topics in the Pharmacopalliation of Serious Illness (P03)

Millennial Workforce: Personality Traits and Motivating Factors

Children born in the 80s and 90s, the Millennials are today‘s 20 to early-30-somethings, poised to make up the majority of the workforce by 2025, and already an important part of the working population. The Millennials, also known as Generation Y, Gen Y and at least a dozen other labels, is now the largest single generation (35%) in the workforce. That makes Millennials a force to be reckoned with. That is a problem for companies who are still trying to figure out how to attract, manage, and retain a younger generation with very different values than the Baby Boomer. Millennials can no longer just be a buzzword thrown around the board room like a hot potato - it is time for organizations to embrace the new workforce majority and start understanding millennials in the workplace, and as a result, embrace the new world of work.

County and Community in Medieval England

Abstract The ‘county community’ is something of a hot potato amongst late medieval political historians. Since the publication of an influential article by Christine Carpenter in 1994, in which she condemned the county community as anachronistic and conceptually flawed, research on the political structures of late medieval England has mostly avoided the term and the idea. In other fields, the methodological challenges and conceptual complexities underpinning the idea of ‘community’ have been embraced and new, more nuanced understandings of how medieval people organised and represented themselves collectively have been achieved. It is now time for historians of politics and government in late medieval England to move beyond reductionist arguments about the existence or otherwise of county communities to investigate the assumptions and social realities that lay behind contemporary references to the ‘commonalty’, ‘commons’ or ‘people’ of one or more counties. This discussion offers the first in-depth analysis of the single most important evidence for grass-roots expressions of county solidarity: county community petitions. It argues that the county was not merely the creation of administrative expedience on the part of the Crown, but provided the basis for real and meaningful expressions of collective identity and corporate action locally. What underpinned the concept of the ‘county community’, and what gave it particular strength, was its inclusivity and flexibility. The discussion concludes by considering the particular circumstances of the early fourteenth century which helped stimulate a culture of corporate identity and self-help on the basis of the county unit.

Body Composition, Diet, and Russet Potato Resistant Starch Influence Glycemic Control (P08-088-19)

ObjectivesResistant starch (RS) is a non-digestible fermentable carbohydrate found naturally in food sources such as potatoes that can lower postprandial glucose and improve insulin sensitivity. Potato RS can be increased by baking then chilling the potato. The purpose of this study is to identify which body composition and dietary outcomes affect glucose and insulin response after female subjects consume a boiled hot Russet potato (∼6 g RS) compared to a baked then chilled Russet potato (∼12 g RS). MethodsSubjects were randomized to consume 250 g of either a chilled or boiled potato with a one week wash-out between the two visits using crossover study design. Three days prior to each visit, dietary intake was obtained from food records. Mean three-day nutrient analysis prior to each visit was analyzed by Nutrition Data System for Research. Body composition (% lean mass (%LM) and fat mass (%FM)) was measured by air displacement plethysmograph at baseline. Fasting and postprandial blood following the intake of each potato were collected for area under the curve (AUC(0–120)) glucose and insulin determination. Spearman’s rho examined the relationship among %FM, %LM, and each mean three-day dietary variables on AUC(0–120) glucose and insulin following each potato intervention. ResultsHealthy overweight (n = 25; mean BMI 31.8 ± 7.4 kg/m2) adult females (mean age 29.0 ± 5.9 years) completed the study. In both chilled and boiled potatoes, AUC(0–120) insulin was significantly positively related to %FM, but significantly inversely related to %LM. AUC(0–120) glucose was not related to body composition. Mean energy, macronutrients, added sugars, total sugars, soluble fiber, and glycemic index were significantly positively related to AUC(0–120) insulin in both chilled and boiled potato; energy and most macronutrients (except fat) were significantly positively related to AUC(0–120) glucose only after boiled potato. ConclusionsA body composition higher in %FM and lower in %LM exhibits less insulin control following potato intake. Higher energy and nutrient intake patterns contribute to less favorable glucose concentrations following boiled potato consumption, but not after chilled potato consumption. The higher RS in the chilled potato may have contributed to glucose homeostasis. Funding SourcesThe Alliance for Potato Research and Education and the University’s Small Grant Program.

역사와 기억 : 건국연도와 연호, 그 정치적 함의

The controversy over the national foundation year of the Republic of Korea(ROK), became a political hot potato for over a decade with regards to the “National Foundation Day”, and “government-designated national history textbook”. The controversy seemed to have been resolved when President Moon Jae-in declared that the foundation year of the ROK as “1919” and that “2019 is the 100th anniversary of the national foundation” in 2017. In addition, declaring national foundation in 1919 was evaluated as being patriotic as such action commemorates Kim Koo and the Provisional Government of the Republic of Korea.<BR> However, based on this study, Syngman Rhee was the actual founder and a leader of ‘1919 national foundation theory’. This theory is first, a way of recollecting the inheritance of legal tradition for Korea without the participation of Kim Koo and his group. Second, a way of recollecting the ROK as not the divided nation but the only central government of the Korean peninsula. Last but not least, an expression of the desire to be unified by the ROK. Behind the curtain of the founding nation theory of 1919, there also was a selfesteem of Syngman Rhee, the President of the Hansung Provisional Government.<BR> The year 2019 is a historic period that marks the 100th anniversary of the 3·1 movement and an establishment of the provisional government. In addition, the year is a period of transition for the Korean Peninsula to surpass beyond the Division, the War, and the Cold War to more expanded terrains.<BR> In the wider perspective of the entire Korean peninsula, the 3·1 Movement, the establishment of the Provisional Government, and the founding of the ROK are separate issues in different dimensions. It is a monopoly and coercion to commemorate above three events comprehensively as one, which also is incompatible with the historical facts of the time. Now is the period to ponder on how to remember the three events in a wider, open view to communicating with North and South.

Fast and slow informed trading

I develop a model in which traders receive a stream of private signals, and differ in their information processing speed. In equilibrium, the fast traders (FTs) quickly reveal a large fraction of their information. If a FT is averse to holding inventory, his optimal strategy changes considerably as his aversion crosses a threshold. He no longer takes long-term bets on the asset value, gets most of his profits in cash, and generates a “hot potato” effect: after trading on information, the FT quickly unloads part of his inventory to slower traders. The results match evidence about high-frequency traders.

Hot Potato Criminology: Ethnographers and the Shame of Poor People's Crimes

When ethnographers study street crime, they anticipate that readers might shame them for shaming the poor. One common response is to compromise the quality of ethnographic data. Another is to pass righteous indignation away from the poor by arguing the causal significance of deindustrialization, class inequalities, racial prejudice, policing, colonialism, or hostility toward immigrants. Almost always, such arguments are gratuitous: The evidence for the structural and historical causes offered by ethnographers does not vary with the situational and biographical variations in behavior that make for high-quality ethnographic data. Nevertheless, if we read around the rhetorical practices that contemporary ethnographers of crime use to shift shame away from their subjects and themselves, we learn how street crime is produced through small criminogenic social circles. Considered as a set, recent ethnographies have significantly advanced knowledge about the social psychology of criminality, and they provide promising leads for improving the understanding of variations in crime patterns over time and across metropolitan spaces.

Multifunctional sulfonated polyetheretherketone coating with beta-defensin-14 for yielding durable and broad-spectrum antibacterial activity and osseointegration

To address periprosthetic joint infection (PJI), a formidable complication after joint arthroplasty, an implant with excellent osseointegration and effective antibacterial activity has being extensively pursued and developed. In this work, the mouse beta-defensin-14 (MBD-14) was immobilized on the polyetheretherketone (PEEK) surface with three-dimensional (3D) porous structure to improve its antibacterial activity and osseointegration. An in vitro antibacterial evaluation showed that the porous PEEK loaded with MBD-14 wages a durable and effective fight against both Staphylococcus aureus (gram-positive) and Pseudomonas aeruginosa (gram-negative). In addition to the superior antibacterial activity, we found that the enhanced proliferation and osteogenic differentiation of bone mesenchymal stem cells were verified through various in vitro analyses. To evaluate the in vivo bactericidal effect and osseointegration of the samples, the rat femoral models with infection and non-infection were established. The enhanced osseointegration of the MBD-14-loaded samples was found in both two in vivo models. And no bacteria survived on the surfaces of samples with a relatively high MBD-14 concentration. Above results indicate that the 3D porous PEEK coating loaded with MBD-14 simultaneously yields excellent osseointegration while exerting durable and broad-spectrum antibacterial activity. And it paves the way for PEEK to be applied clinically to address PJI. Statement of significance(1). By using the physio-chemical technique including sulfonation and lyophilization etc., a three-dimensional porous network is developed on polyetheretherketone (PEEK) surface, in which mouse beta-defensin-14 (MBD-14, a broad-spectrum antimicrobial peptide) is then loaded. It endows PEEK with antibacterial activity and osseointegration. (2). Two in vivo animal models with infection and non-infection are used to prove the new bone formation around the samples. (3). Supplementary material also proves that MBD-14 promotes the osteogenic differentiation of BMSCs. However, its potential mechanism needs to be further studied in future. (4). The modified PEEK, including excellent osseointegration and a durable and broad-spectrum antibacterial activity, could be applied clinically to address PJI which is a hot potato for surgeons and patients undergoing total joint arthroplasty.

The "Hot Potato" of Mental Health App Regulation: A Critical Case Study of the Australian Policy Arena.

Background: Health apps are a booming, yet under-regulated market, with potential consumer harms in privacy and health safety. Regulation of the health app market tends to be siloed, with no single sector holding comprehensive oversight. We sought to explore this phenomenon by critically analysing how the problem of health app regulation is being presented and addressed in the policy arena. Methods: We conducted a critical, qualitative case study of regulation of the Australian mental health app market. We purposively sampled influential policies from government, industry and non-profit organisations that provided oversight of app development, distribution or selection for use. We used Bacchi’s critical, theoretical approach to policy analysis, analysing policy solutions in relation to the ways the underlying problem was presented and discussed. We analysed the ways that policies characterised key stakeholder groups and the rationale policy authors provided for various mechanisms of health app oversight. Results: We identified and analysed 29 policies from Australia and beyond, spanning 5 sectors: medical device, privacy, advertising, finance, and digital content. Policy authors predominantly framed the problem as potential loss of commercial reputations and profits, rather than consumer protection. Policy solutions assigned main responsibility for app oversight to the public, with a heavy onus on consumers to select safe and high-quality apps. Commercial actors, including powerful app distributors and commercial third parties were rarely subjects of policy initiatives, despite having considerable power to affect app user outcomes. Conclusion: A stronger regulatory focus on app distributors and commercial partners may improve consumer privacy and safety. Policy-makers in different sectors should work together to develop an overarching regulatory framework for health apps, with a focus on consumer protection.

Discrimination of “hot potato voice” caused by upper airway obstruction utilizing a support vector machine

"Hot potato voice" (HPV) is a thick, muffled voice caused by pharyngeal or laryngeal diseases characterized by severe upper airway obstruction, including acute epiglottitis and peritonsillitis. To develop a method for determining upper-airway emergency based on this important vocal feature, we investigated the acoustic characteristics of HPV using a physical, articulatory speech synthesis model. The results of the simulation were then applied to design a computerized recognition framework using a mel-frequency cepstral coefficient domain support vector machine (SVM). Quasi-experimental research design. Changes in the voice spectral envelope caused by upper airway obstructions were analyzed using a hybrid time-frequency model of articulatory speech synthesis. We evaluated variations in the formant structure and thresholds of critical vocal tract area functions that triggered HPV. The SVMs were trained using a dataset of 2,200 synthetic voice samples generated by an articulatory synthesizer. Voice classification experiments on test datasets of real patient voices were then performed. On phonation of the Japanese vowel /e/, the frequency of the second formant fell and coalesced with that of the first formant as the area function of the oropharynx decreased. Changes in higher-order formants varied according to constriction location. The highest accuracy afforded by the SVM classifier trained with synthetic data was 88.3%. HPV caused by upper airway obstruction has a highly characteristic spectral envelope. Based on this distinctive voice feature, our SVM classifier, who was trained using synthetic data, was able to diagnose upper-airway obstructions with a high degree of accuracy. 2c Laryngoscope, 129:1301-1307, 2019.

BOND: Flexible failure recovery in software defined networks

Failure recovery has been a hot potato in the maintenance of networks, including software defined networks (SDNs), for many years. To guarantee the network availability in SDNs, some delicate schemes and algorithms have been proposed to pre-compute and set up the backup paths for potential network failures. However, they are generally unpractical for deployment, since they ignore either the failure recovery requirements of different flows or the constrained resources (e.g., flow tables) of SDN switches.In this paper, we propose BOND, a flexible failure recovery system in SDNs. Firstly, we allocate backup rules, instead of backup paths, to forwarding switches with flows’ requirements considered. Secondly, we accelerate the failure recovery with a global hash table and precisely select backup paths to avoid potential congestions in the post-recovery network. To demonstrate the efficiency of BOND, we construct comprehensive experiments with real-world topologies. The results show that compared with Multi-Protocol Label Switching (MPLS) Fast Reroute (FRR), BOND consumes an order of magnitude less memory to achieve the same network recovery goal. Further, we implement BOND with five HUAWEI S5720 SDN switches, two Dell end hosts and a RYU controller. The prototype experiments of this real network implementation further confirm the efficiency of BOND.