title: Light, camera, actions: characterizing the usage of IXPs' action BGP communities

authors: Mazzola, Fabricio

subjects: computer science

abstract: Border Gateway Protocol (BGP) communities, an optional message attribute, allow network operators to tag BGP announcements and act on routing decisions. Although widely used, it is so far unclear how prevalent the different types of communities are and the degree to which the different traffic engineering actions have been used. There are two major reasons for this gap: few community values have been standardised and the limited visibility at route collectors. In this paper, leveraging the fact that Internet eXchange Points (IXPs) have sets of well-documented BGP communities, we use their BGP Looking Glasses (LGs) to inspect their route servers and shed light on how IXP members are using action BGP communities. During twelve weeks, we collected and analysed routing data from eight IXPs worldwide, focusing the analysis on the four largest IXPs. We observe that i) over one-third of IXP members (>35.7%) use action communities in at least one route; ii) two-thirds (66.6%) of them are intended to avoid propagating routes, mostly to content providers (CPs); iii) nearly one-third (31.8%) are targeting Autonomous Systems (ASes) that are not present at the IXPs' route servers, resulting in no practical routing effect and only increasing processing and memory storage overheads.

text: Light, camera, actions: characterizing the usage of IXPs' action BGP communities Border Gateway Protocol (BGP) communities, an optional message attribute, allow network operators to tag BGP announcements and act on routing decisions. Although widely used, it is so far unclear how prevalent the different types of communities are and the degree to which the different traffic engineering actions have been used. There are two major reasons for this gap: few community values have been standardised and the limited visibility at route collectors. In this paper, leveraging the fact that Internet eXchange Points (IXPs) have sets of well-documented BGP communities, we use their BGP Looking Glasses (LGs) to inspect their route servers and shed light on how IXP members are using action BGP communities. During twelve weeks, we collected and analysed routing data from eight IXPs worldwide, focusing the analysis on the four largest IXPs. We observe that i) over one-third of IXP members (>35.7%) use action communities in at least one route; ii) two-thirds (66.6%) of them are intended to avoid propagating routes, mostly to content providers (CPs); iii) nearly one-third (31.8%) are targeting Autonomous Systems (ASes) that are not present at the IXPs' route servers, resulting in no practical routing effect and only increasing processing and memory storage overheads.

year: 2022-12-06

title: Approximation of invariant measures for a class of maps with indifferent fixed points

authors: Murray, Rua

subjects: mathematics

abstract: Certain dynamical systems on the interval with neutrally stable repelling points admit invariant probability measures which are absolutely continuous with respect to Lebesgue measure. These maps are often used as a model of intermittent dynamics, since they exhibit polynomial rather than exponential decay of correlations (due to the absence of a spectral gap in the underlying transfer operator). This paper presents a class of these maps which are expanding (with convex branches) for which the invariant probability measures can be rigorously approximated by Ulam’s method (a sequence of finite rank approximations to the transfer operator). L1–convergence of the scheme is proved, and some numerical experiments are reported.

text: Approximation of invariant measures for a class of maps with indifferent fixed points Certain dynamical systems on the interval with neutrally stable repelling points admit invariant probability measures which are absolutely continuous with respect to Lebesgue measure. These maps are often used as a model of intermittent dynamics, since they exhibit polynomial rather than exponential decay of correlations (due to the absence of a spectral gap in the underlying transfer operator). This paper presents a class of these maps which are expanding (with convex branches) for which the invariant probability measures can be rigorously approximated by Ulam’s method (a sequence of finite rank approximations to the transfer operator). L1–convergence of the scheme is proved, and some numerical experiments are reported.

year: 2005

title: Race-ing and engendering the nation-state in Aotearoa/New Zealand

authors: Seuffert, Nan

subjects: Maori

abstract: During the past several decades the dynamics of law and policy reform in Aotearoa/New Zealand have prefigured and encapsulated contemporary trends in economic state restructuring, indigenous claims to refigure the nation, and gender struggles for political representation. Successive governments have restructured the economy and the state using radical forms of neo-liberal economic policy with the stated aim of globalizing the economy. Political action on the part of the indigenous Maori people, often led by Maori women, increased and diversified, and included demands for self-determination and redress of historical colonial injustices. In 1997, the conservative National Party’s Jenny Shipley become the country’s first white female Prime Minister, followed in 1999 by the election of a center-left coalition headed by Labour Party leader Helen Clark. This article analyzes the race and gender dynamics of these contemporary trends. First, it argues that policies of state structural adjustment and Maori political claims have converged in commodified settlements of past colonial injustices as corporate deals. These deals are temporary alliances of men across race to silence and erase the demands for self-determination or political power sharing of Maori activists, who are usually Maori women. Second, this article contends that the political instability created by rapid structural adjustment and the change to a Mixed Member Proportional (“MMP”) electoral system converges with white backlash against these settlements to open space for New Zealand’s first two female Prime Ministers. This article also suggests that the election of a second white female Prime Minister in New Zealand may reflect the (temporary) regendering of the role of Prime Minister to the feminine.

text: Race-ing and engendering the nation-state in Aotearoa/New Zealand During the past several decades the dynamics of law and policy reform in Aotearoa/New Zealand have prefigured and encapsulated contemporary trends in economic state restructuring, indigenous claims to refigure the nation, and gender struggles for political representation. Successive governments have restructured the economy and the state using radical forms of neo-liberal economic policy with the stated aim of globalizing the economy. Political action on the part of the indigenous Maori people, often led by Maori women, increased and diversified, and included demands for self-determination and redress of historical colonial injustices. In 1997, the conservative National Party’s Jenny Shipley become the country’s first white female Prime Minister, followed in 1999 by the election of a center-left coalition headed by Labour Party leader Helen Clark. This article analyzes the race and gender dynamics of these contemporary trends. First, it argues that policies of state structural adjustment and Maori political claims have converged in commodified settlements of past colonial injustices as corporate deals. These deals are temporary alliances of men across race to silence and erase the demands for self-determination or political power sharing of Maori activists, who are usually Maori women. Second, this article contends that the political instability created by rapid structural adjustment and the change to a Mixed Member Proportional (“MMP”) electoral system converges with white backlash against these settlements to open space for New Zealand’s first two female Prime Ministers. This article also suggests that the election of a second white female Prime Minister in New Zealand may reflect the (temporary) regendering of the role of Prime Minister to the feminine.

year: 2002-02-01