title: Identifying equivalent SDN forwarding behaviour

authors: Sanger, Richard

subjects: computer science

abstract: Software-Defined Networking (SDN) enables network operators the flexibility to program their own forwarding rules, providing more than one way to achieve the same behaviour. Verifying equivalence between rulesets is a fundamental analysis and verification building block for SDN as it can be used to: (1) confirm a ruleset optimised for power efficiency or table occupancy remains equivalent, (2) verify a ruleset modified for new hardware, (3) regression test an SDN application to detect bugs early.
We present a practical and novel canonical Multi-Terminal Binary Decision Diagram (MTBDD) representation of OpenFlow 1.3 ruleset forwarding behaviour which can be trivially compared for equivalence. Basing our representation on an MTBDD provides a proven canonical form which is also compact. In this paper, we present the algorithms required to correctly flatten multi-table pipelines into an equivalent single-table, resolve equivalences in OpenFlow actions, and build the final MTBDD representation from a priority ordered ruleset. OpenFlow rulesets can typically be converted to an MTBDD within tens of seconds. We release our opensource implementation to the SDN community.

text: Identifying equivalent SDN forwarding behaviour Software-Defined Networking (SDN) enables network operators the flexibility to program their own forwarding rules, providing more than one way to achieve the same behaviour. Verifying equivalence between rulesets is a fundamental analysis and verification building block for SDN as it can be used to: (1) confirm a ruleset optimised for power efficiency or table occupancy remains equivalent, (2) verify a ruleset modified for new hardware, (3) regression test an SDN application to detect bugs early.
We present a practical and novel canonical Multi-Terminal Binary Decision Diagram (MTBDD) representation of OpenFlow 1.3 ruleset forwarding behaviour which can be trivially compared for equivalence. Basing our representation on an MTBDD provides a proven canonical form which is also compact. In this paper, we present the algorithms required to correctly flatten multi-table pipelines into an equivalent single-table, resolve equivalences in OpenFlow actions, and build the final MTBDD representation from a priority ordered ruleset. OpenFlow rulesets can typically be converted to an MTBDD within tens of seconds. We release our opensource implementation to the SDN community.

year: 2019

title: Clinical Governance, Performance Appraisal and Interactional and Procedural Fairness at a New Zealand Public Hospital

authors: Clarke, Carol

subjects: clinical governance

abstract: This paper explores the conduct of performance appraisals of nurses in a New Zealand hospital, and how fairness is perceived in such appraisals. In the health sector, performance appraisals of medical staff play a key role in implementing clinical governance, which, in turn, is critical to containing health care costs and ensuring quality patient care. Effective appraisals depend on employees perceiving their own appraisals to be fair both in terms of procedure and interaction with their respective appraiser. We examine qualitative data from interviews and focus groups, involving 22 nurses in a single department, to determine whether perceived injustices impact on the effective implementation of the appraisal system. Our results suggest that particular issues had been causing some sense of injustice, and most of these were procedural. Potential solutions focus on greater formalisation of the performance appraisal process, and more training for appraisers and appraisees.

text: Clinical Governance, Performance Appraisal and Interactional and Procedural Fairness at a New Zealand Public Hospital This paper explores the conduct of performance appraisals of nurses in a New Zealand hospital, and how fairness is perceived in such appraisals. In the health sector, performance appraisals of medical staff play a key role in implementing clinical governance, which, in turn, is critical to containing health care costs and ensuring quality patient care. Effective appraisals depend on employees perceiving their own appraisals to be fair both in terms of procedure and interaction with their respective appraiser. We examine qualitative data from interviews and focus groups, involving 22 nurses in a single department, to determine whether perceived injustices impact on the effective implementation of the appraisal system. Our results suggest that particular issues had been causing some sense of injustice, and most of these were procedural. Potential solutions focus on greater formalisation of the performance appraisal process, and more training for appraisers and appraisees.

year: 2012

title: Te Whariki revisited: How approaches to assessment can make valued learning visible

authors: McLachlan, Claire

abstract: In 2016, Te Whariki: He Whariki Matauranga mō ngā Mokopuna o Aotearoa: Early Childhood Curriculum (Te Whariki) (Ministry of Education [MoE], 2017), New Zealand’s early childhood curriculum was updated for the first time in 20 years. Although the gazetted principles, strands and goals of the curriculum were not part of the update, the remainder of the curriculum was revised to meet the changing social and linguistic context, the revised national curriculum and associated documents, reviews of early childhood practice and relevant theory and research. The updated curriculum has reduced learning outcomes (from 118 to 20) and stronger guidance on the need for both informal and formal approaches to assessment to ensure children’s learning in each strand are assessed. This article reflects on the changes between the 1996 and 2017 version of the curriculum in relation to assessment and the rationale for the changes. Approaches to both ‘in the moment’ and planned assessment are explored and the usefulness of approaches which enable teachers to reflect on ‘discrepant data’ and support children’s learning in each strand are examined.

text: Te Whariki revisited: How approaches to assessment can make valued learning visible In 2016, Te Whariki: He Whariki Matauranga mō ngā Mokopuna o Aotearoa: Early Childhood Curriculum (Te Whariki) (Ministry of Education [MoE], 2017), New Zealand’s early childhood curriculum was updated for the first time in 20 years. Although the gazetted principles, strands and goals of the curriculum were not part of the update, the remainder of the curriculum was revised to meet the changing social and linguistic context, the revised national curriculum and associated documents, reviews of early childhood practice and relevant theory and research. The updated curriculum has reduced learning outcomes (from 118 to 20) and stronger guidance on the need for both informal and formal approaches to assessment to ensure children’s learning in each strand are assessed. This article reflects on the changes between the 1996 and 2017 version of the curriculum in relation to assessment and the rationale for the changes. Approaches to both ‘in the moment’ and planned assessment are explored and the usefulness of approaches which enable teachers to reflect on ‘discrepant data’ and support children’s learning in each strand are examined.

year: 2018