This paper studies PIFO trees from a programming language perspective. PIFO
trees are a recently proposed model for programmable packet schedulers. They
can express a wide range of scheduling algorithms including strict priority,
weighted fair queueing, hierarchical schemes, and more. However, their semantic
properties are not well understood. We formalize the syntax and semantics of
PIFO trees in terms of an operational model. We also develop an alternate
semantics in terms of permutations on lists of packets, prove theorems
characterizing expressiveness, and develop an embedding algorithm for
replicating the behavior of one with another. We present a prototype
implementation of PIFO trees in OCaml and relate its behavior to a hardware
switch on a variety of standard and novel scheduling algorithms.Comment: 25 pages, 12 figure

Foster, Nate

Kappé, Tobias

Kozen, Dexter

Liu, Yunhe

Mohan, Anshuman

English

arXiv

Early programming models for software-defined networking (SDN) focused on basic features for controlling network-wide forwarding paths, but more recent work has considered richer features, such as packet scheduling and queueing, that affect performance. In particular, PIFO trees, proposed by Sivaraman et al., offer a flexible and efficient primitive for programmable packet scheduling. Prior work has shown that PIFO trees can express a wide range of practical algorithms including strict priority, weighted fair queueing, and hierarchical schemes. However, the semantic properties of PIFO trees are not well understood. This paper studies PIFO trees from a programming language perspective. We formalize the syntax and semantics of PIFO trees in an operational model that decouples the scheduling policy running on a tree from the topology of the tree. Building on this formalization, we develop compilation algorithms that allow the behavior of a PIFO tree written against one topology to be realized using a tree with a different topology. Such a compiler could be used to optimize an implementation of PIFO trees, or realize a logical PIFO tree on a target with a fixed topology baked into the hardware. To support experimentation, we develop a software simulator for PIFO trees, and we present case studies illustrating its behavior on standard and custom algorithms.</div

Mohan, A.

Liu, Y.

Foster, N.

Kappé, T.

Kozen, D.

UvA-DARE

Formal Abstractions for Packet Scheduling

Early programming models for software-defined networking (SDN) focused on
basic features for controlling network-wide forwarding paths, but more recent
work has considered richer features, such as packet scheduling and queueing,
that affect performance. In particular, PIFO trees, proposed by Sivaraman et
al., offer a flexible and efficient primitive for programmable packet
scheduling. Prior work has shown that PIFO trees can express a wide range of
practical algorithms including strict priority, weighted fair queueing, and
hierarchical schemes. However, the semantic properties of PIFO trees are not
well understood.
  This paper studies PIFO trees from a programming language perspective. We
formalize the syntax and semantics of PIFO trees in an operational model that
decouples the scheduling policy running on a tree from the topology of the
tree. Building on this formalization, we develop compilation algorithms that
allow the behavior of a PIFO tree written against one topology to be realized
using a tree with a different topology. Such a compiler could be used to
optimize an implementation of PIFO trees, or realize a logical PIFO tree on a
target with a fixed topology baked into the hardware. To support
experimentation, we develop a software simulator for PIFO trees, and we present
case studies illustrating its behavior on standard and custom algorithms

arXiv.org e-Print Archive

International Migration, Integration and Social Cohesion online publications

Early programming models for software-defined networking (SDN) focused on basic features for controlling network-wide forwarding paths, but more recent work has considered richer features, such as packet scheduling and queueing, that affect performance. In particular, PIFO trees, proposed by Sivaraman et al., offer a flexible and efficient primitive for programmable packet scheduling. Prior work has shown that PIFO trees can express a wide range of practical algorithms including strict priority, weighted fair queueing, and hierarchical schemes. However, the semantic properties of PIFO trees are not well understood.This paper studies PIFO trees from a programming language perspective. We formalize the syntax and semantics of PIFO trees in an operational model that decouples the scheduling policy running on a tree from the topology of the tree. Building on this formalization, we develop compilation algorithms that allow the behavior of a PIFO tree written against one topology to be realized using a tree with a different topology. Such a compiler could be used to optimize an implementation of PIFO trees, or realize a logical PIFO tree on a target with a fixed topology baked into the hardware. To support experimentation, we develop a software simulator for PIFO trees, and we present case studies illustrating its behavior on standard and custom algorithms

Open University of the Netherlands Research Portal

https://pure.uva.nl/ws/files/149959986/3622845.pdf

Formal Abstractions for Packet Scheduling

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arXiv.org e-Print Archive

International Migration, Integration and Social Cohesion online publications

Open University of the Netherlands Research Portal