Performance bounds in wormhole routing, a network calculus approach

TL;DR

This paper develops a network calculus framework for deriving performance bounds in wormhole-routed networks, introducing packet curves to model variable packet lengths and calculating worst-case delays and backlogs.

Contribution

It introduces packet curves for modeling variable packet lengths and provides a method to compute residual services and performance bounds in wormhole routing networks.

Findings

Derived worst-case delay bounds for wormhole switches

Introduced packet curves for variable packet length modeling

Extended approach to feedforward network topologies

Abstract

We present a model of performance bound calculus on feedforward networks where data packets are routed under wormhole routing discipline. We are interested in determining maximum end-to-end delays and backlogs of messages or packets going from a source node to a destination node, through a given virtual path in the network. Our objective here is to give a network calculus approach for calculating the performance bounds. First we propose a new concept of curves that we call packet curves. The curves permit to model constraints on packet lengths of a given data flow, when the lengths are allowed to be different. Second, we use this new concept to propose an approach for calculating residual services for data flows served under non preemptive service disciplines. Third, we model a binary switch (with two input ports and two output ports), where data is served under wormhole discipline. We present our approach for computing the residual services and deduce the worst case bounds for flows passing through a wormhole binary switch. Finally, we illustrate this approach in numerical examples, and show how to extend it to feedforward networks.