RSTP — Rapid Spanning Tree
Definition
RSTP (Rapid Spanning Tree Protocol, IEEE 802.1w, later incorporated into IEEE 802.1D-2004 and IEEE 802.1Q) prevents loops in a switched network while keeping redundant links available as backups. The switches exchange BPDU messages, elect a root bridge and block the redundant ports, which they reopen when an active link fails. Without spanning tree, a loop causes a broadcast storm that can saturate the network within seconds. RSTP usually restores connectivity within a few seconds, often in less than one, against 30 to 50 seconds for the original STP. d&b audiotechnik describes ring and mesh Dante topologies built with RSTP, on the condition that every switch in the loop supports it and is configured correctly.
In the field
An accidental loop on switches without spanning tree causes a broadcast storm that can stop all audio within seconds. Dante redundancy relies on two separate networks, with separate interfaces and separate switches, and not on a loop through one switch. When RSTP runs alongside Dante, every switch in the loop runs it, and edge-port settings such as PortFast are applied only to ports that lead to end devices, never to links between switches.
Sources
- Accuenergy, Rapid Spanning Tree Protocol : recalcul de topologie en environ 300 ms après une panne · accuenergy.com
- Spanning Tree Protocol (Wikipedia, pointeur secondaire) : STP classique 30 à 50 s, RSTP plus rapide ; tempête de broadcast en cas de boucle · en.wikipedia.org
- d&b audiotechnik, TI 317 Dante audio networking : le RSTP permet des topologies en anneau ou maillées, à condition d'être pris en charge et correctement configuré sur tous les switches de la boucle · dbaudio.com
- Cisco, Understand Rapid Spanning Tree Protocol (802.1w) : l'IEEE 802.1D-2004 intègre l'IEEE 802.1w ; ports d'extrémité (edge ports) réservés aux stations, liens point à point entre switches · cisco.com
- IEEE 802.1D (Wikipedia, pointeur secondaire) : l'802.1D-2004 remplace le STP d'origine par le RSTP ; fonctions reprises dans l'IEEE 802.1Q · en.wikipedia.org
- Audinate, Dante Controller User Guide : réseaux primaire et secondaire séparés pour la redondance · dev.audinate.com