# TRIDENT: A load-balancing Clos-network Packet Switch with Queues between Input and Central Stages and In-Order Forwarding

## TL;DR

TRIDENT is a three-stage load balancing packet switch with a novel configuration scheme that ensures high throughput, in-sequence forwarding, and low complexity without requiring central-stage expansion or memory speedup.

## Contribution

It introduces a new three-stage Clos-network switch with queues at the middle stage and a deterministic configuration scheme for load balancing and routing.

## Key findings

- Achieves 100% throughput under various traffic conditions.
- Ensures in-sequence forwarding without additional complexity.
- Demonstrates high performance through simulation analysis.

## Abstract

We propose a three-stage load balancing packet switch and its configuration scheme. The input- and central-stage switches are bufferless crossbars, and the output-stage switches are buffered crossbars. We call this switch ThRee-stage Clos-network swItch with queues at the middle stage and DEtermiNisTic scheduling (TRIDENT), and the switch is cell based. The proposed configuration scheme uses predetermined and periodic interconnection patterns in the input and central modules to load-balance and route traffic, therefore; it has low configuration complexity. The operation of the switch includes a mechanism applied at input and output modules to forward cells in sequence. TRIDENT achieves 100% throughput under uniform and nonuniform admissible traffic with independent and identical distributions (i.i.d.). The switch achieves this high performance using a low-complexity architecture while performing in-sequence forwarding and no central-stage expansion or memory speedup. Our discussion includes throughput analysis, where we describe the operations the configuration mechanism performs on the traffic traversing the switch, and proof of in-sequence forwarding. We present a simulation analysis as a practical demonstration of the switch performance under uniform and nonuniform i.i.d. traffic.