Signalling Protocol for P4 (SPP4), Version 1.0

This document describes SPP4 v.1.0, a signalling protocol implemented on Programmable Protocol Processing Pipeline (P4) platform. Protocol has been implemented on P4 v.1. It is expected that P4 v.2 will use a modified version of this protocol to support new features. Current version of the signaling protocol allows P4 boards to synchronize their activities. Protocol Boosters model is supported and it is assumed that the mechanism modules are already available at each of the P4 enhanced nodes. Providing the mechanism modules from by the end user is not supported yet. The signaling protocol is specified to support non-transparent boosters (i.e. boosters that require deboosters). If only transparent boosters are used (i.e. those that can operate without debooster), some of the features may be unnecessary. The existing implementation can work with transparent boosters but it will have more overhead than necessary. This document covers protocol specification, interaction between signaling protocol and policy modules and software architectures of current implementation. The purpose of this document is to explain, not to formally specify the SPP4

Immunization and Aging: a Learning Process in the Immune Network

The immune system can be thought as a complex network of different interacting elements. A cellular automaton, defined in shape-space, was recently shown to exhibit self-regulation and complex behavior and is, therefore, a good candidate to model the immune system. Using this model to simulate a real immune system we find good agreement with recent experiments on mice. The model exhibits the experimentally observed refractory behavior of the immune system under multiple antigen presentations as well as loss of its plasticity caused by aging.Comment: 4 latex pages, 3 postscript figures attached. To be published in Physical Review Letters (Tentatively scheduled for 5th Oct. issue

Active networks: an evolution of the internet

Active Networks can be seen as an evolution of the classical model of packet-switched networks. The traditional and ”passive” network model is based on a static definition of the network node behaviour. Active Networks propose an “active” model where the intermediate nodes (switches and routers) can load and execute user code contained in the data units (packets). Active Networks are a programmable network model, where bandwidth and computation are both considered shared network resources. This approach opens up new interesting research fields. This paper gives a short introduction of Active Networks, discusses the advantages they introduce and presents the research advances in this field

Regulating and resisting queer creativity: community-engaged arts practice in the neoliberal city

This article draws from and advances urban studies literature on ‘creative city’ policies by exploring the contradictory role of queer arts practice in contemporary placemarketing strategies. Here I reflect on the fraught politics surrounding Radiodress’s each hand as they are called project, a deeply personal exploration of radical Jewish history programmed within Luminato, a Toronto-based international festival of creativity. Specifically, I explore how Luminato and the Koffler Centre, a Jewish organisation promoting contemporary art, regulated Radiodress’s work in order to stage marketable notions of ethnic and queer diversity. I also examine how and why the Koffler Centre eventually blacklisted Radiodress and her project. However, I also consider the ways Radiodress and Toronto artists creatively and collectively responded to these tensions. I maintain that bringing queer arts practice into discussions about contemporary creative city policies uncovers sites of queer arts activism that scale up to shape broader policies and debates. Such disidentificatory interventions, acts of co-opting and re-working discourses which exclude minoritarian subjects, challenge violent processes of colonisation and commodification on multiple fronts, as well as fostering more collective and relational ways of being

Nonlinear shell analyses of the space shuttle solid rocket boosters

A variety of structural analyses have been performed on the Solid Rocket Boosters (SRB's) to provide information that would contribute to the understanding of the failure which destroyed the Space Shuttle Challenger. This paper describes nonlinear shell analyses that were performed to characterize the behavior of an overall SRB structure and a segment of the SRB in the vicinity of the External Tank Attachment (ETA) ring. Shell finite element models were used that would accurately reflect the global load transfer in an SRB in a manner such that nonlinear shell collapse and ovalization could be assessed. The purpose of these analyses was to calculate the overall deflection and stress distributions for these SRB models when subjected to mechanical loads corresponding to critical times during the launch sequence. Static analyses of these SRB models were performed using a snapshot picture of the loads. Analytical results obtained using these models show no evidence of nonlinear shell collapse for the pre-liftoff loading cases considered

Active networking : one view of the past, present, and future

All distributed computing systems face the architectural question of the location (and nature) of programmability in the telecommunications networks, computers, and other peripheral devices comprising them. The perspective of this paper is that network elements should be as programmable as possible, to enable the most flexible distributed computing systems. There has been a persistent confluence among operating systems, programming languages, networking and distributed systems. We demonstrate how these interactions led to what is called active networking , and in the spirit of vox audita perit, littera scripta manet (the spoken word perishes, but the written word remains), include an account of how it was made to happen. Lessons are drawn both from the broader research agenda, and the specific goals pursued in the SwitchWare project. We speculate on likely futures for active networking

Reflections on Active Networking

Interactions among telecommunications networks, computers, and other peripheral devices have been of interest since the earliest distributed computing systems. A key architectural question is the location (and nature) of programmability. One perspective, that examined in this paper, is that network elements should be as programmable as possible, in order to build the most flexible distributed computing systems. This paper presents my personal view of the history of programmable networking over the last two decades, and in the spirit of vox audita perit, littera scripta manet , includes an account of how what is now called Active Networking came into being. It demonstrates the deep roots Active Networking has in the programming languages, networking and operating systems communities, and shows how interdisciplinary approaches can have impacts greater than the sums of their parts. Lessons are drawn both from the broader research agenda, and the specific goals pursued in the SwitchWare project. I close by speculating on possible futures for Active Networking