title: Efficient Internet Topology Discovery Techniques

authors: King, Alistair John

subjects: Internet topology discovery

abstract: Current macroscopic Internet topology discovery projects use large numbers of vantage points to conduct traceroute surveys of Internet paths. These projects send billions of unsolicited packets to millions of routers within the Internet. Due to the structure of the Internet, many of these packets are sent without gaining any new topology information. In this thesis, we implement and extensively test a largescale doubletree system designed to increase the efficiency of topology mapping projects and reduce the load that they place on the Internet. Also, for all of the effort that current projects put into gathering data, the methods used do not discover, with confidence, the entire set of paths. We propose, implement and critique a novel algorithm, economical MDA traceroute, which is designed to discover a comprehensive topology in a manner which is more efficient than the current state of the art. We show that, compared to current methods, well over 90% link coverage can be obtained while reducing the number of probes used by over 60%. We also evaluate alternate methods for making large scale topology discovery projects more efficient and comprehensive; such as using BGP routing data to guide probing.

text: Efficient Internet Topology Discovery Techniques Current macroscopic Internet topology discovery projects use large numbers of vantage points to conduct traceroute surveys of Internet paths. These projects send billions of unsolicited packets to millions of routers within the Internet. Due to the structure of the Internet, many of these packets are sent without gaining any new topology information. In this thesis, we implement and extensively test a largescale doubletree system designed to increase the efficiency of topology mapping projects and reduce the load that they place on the Internet. Also, for all of the effort that current projects put into gathering data, the methods used do not discover, with confidence, the entire set of paths. We propose, implement and critique a novel algorithm, economical MDA traceroute, which is designed to discover a comprehensive topology in a manner which is more efficient than the current state of the art. We show that, compared to current methods, well over 90% link coverage can be obtained while reducing the number of probes used by over 60%. We also evaluate alternate methods for making large scale topology discovery projects more efficient and comprehensive; such as using BGP routing data to guide probing.

year: 2010

title: A warm and dry place to live: Energy efficiency and rental accommodation

authors: Barton, Barry

abstract: In residential tenancies, it is usual for the landlord to be responsible for the fabric of the building and the main appliances, and for the tenant to be responsible for paying for electricity, gas and other fuel. It is also the tenant who is affected by the building’s heating and ventilation performance – whether it can be kept warm and dry without undue expense. A landlord has no financial incentive to invest in extra insulation or better appliances, because the benefits will be reaped by the tenant in lower energy bills and higher levels of comfort, and because the improvements do not have a direct influence on the rent that the landlord can charge. The result is that energy efficiency investments tend not to get made. In policy terms, the interests of the landlord and tenant are not aligned; the incentives are split. It is a classic example of a principal-agent gap, and as the “landlord-tenant problem” is one of the market failures that affects efficiency in markets for energy and energy products.1 The energy use affected by the principal-agent problem in the United States residential sector for refrigerators, space heating, water heating and lighting has been estimated as 31.4 per cent of the total sectoral energy use;2 so the issue is a substantial one. The problem of energy efficiency in rental accommodation is therefore the subject of this article.

text: A warm and dry place to live: Energy efficiency and rental accommodation In residential tenancies, it is usual for the landlord to be responsible for the fabric of the building and the main appliances, and for the tenant to be responsible for paying for electricity, gas and other fuel. It is also the tenant who is affected by the building’s heating and ventilation performance – whether it can be kept warm and dry without undue expense. A landlord has no financial incentive to invest in extra insulation or better appliances, because the benefits will be reaped by the tenant in lower energy bills and higher levels of comfort, and because the improvements do not have a direct influence on the rent that the landlord can charge. The result is that energy efficiency investments tend not to get made. In policy terms, the interests of the landlord and tenant are not aligned; the incentives are split. It is a classic example of a principal-agent gap, and as the “landlord-tenant problem” is one of the market failures that affects efficiency in markets for energy and energy products.1 The energy use affected by the principal-agent problem in the United States residential sector for refrigerators, space heating, water heating and lighting has been estimated as 31.4 per cent of the total sectoral energy use;2 so the issue is a substantial one. The problem of energy efficiency in rental accommodation is therefore the subject of this article.

year: 2013

title: Listening and Learning from Rangatahi Māori: the Voices of Māori Youth

authors: Berryman, Mere

subjects: student self-determination

abstract: This paper presents three stories-over-time of the secondary schooling experiences of New Zealand’s rangatahi Māori–or Māori youth. The stories span fifteen years of New Zealand schooling and are told from three perspectives: the experiences of the students as told in their own words; the voices of youth within the prevailing political contexts of government policy; and, the reframing and repositioning of researchers listening to the experiences of rangatahi Māori who believe they have succeeded as Māori. In reality, the stories are interwoven, however, in an effort to make sense of the various methodological dilemmas, risks, and entanglements across the three points of learning, we have endeavored to disentangle these different threads from the whole and follow these independent of each other. We then weave these threads together again, as we sense-make across this complexity to identify implications for other educators, policy makers and researchers.

text: Listening and Learning from Rangatahi Māori: the Voices of Māori Youth This paper presents three stories-over-time of the secondary schooling experiences of New Zealand’s rangatahi Māori–or Māori youth. The stories span fifteen years of New Zealand schooling and are told from three perspectives: the experiences of the students as told in their own words; the voices of youth within the prevailing political contexts of government policy; and, the reframing and repositioning of researchers listening to the experiences of rangatahi Māori who believe they have succeeded as Māori. In reality, the stories are interwoven, however, in an effort to make sense of the various methodological dilemmas, risks, and entanglements across the three points of learning, we have endeavored to disentangle these different threads from the whole and follow these independent of each other. We then weave these threads together again, as we sense-make across this complexity to identify implications for other educators, policy makers and researchers.

year: 2017