Interplay Between Priority Queues and Controlled Delay in Programmable Data Planes

Abstract

The Tactile Internet needs to support multiple modalities, including haptic data simultaneously, to enable human and robot interaction in perceived real-time. Compared to video and audio, haptic data streams require an even lower delay and more shallow packet loss, which is a challenge for the underlying networks originally designed to support high bandwidths by having a large queue to buffer packets. This raises the need to study queuing management for different data streams. We examine the performance of CoDel++, which combines the well-known Controlled Delay (CoDel) protocol and Priority Queues. We leverage programmable data planes, which can be programmed with P4. Evaluation results show that CoDel++ produces superior results for high-priority data streams, i.e., reducing latency by at least 60% and packet loss by half compared to individual exploitation of Priority Queuing or CoDel individually.