VLANs
Definition
A VLAN (virtual LAN), defined by the IEEE 802.1Q standard, divides one physical switch fabric into several logical networks that do not exchange traffic at layer 2, although they share the same hardware. Audio, video, lighting control and management can each be placed in their own VLAN, so that multicast video does not reach the audio devices and control traffic stays out of the media path. Each VLAN is a separate broadcast domain, which keeps broadcast and flooded multicast traffic inside it. Traffic between two VLANs has to pass through a router or a layer 3 switch.
The guide
Between switches, several VLANs share one link called a trunk. Each frame on the trunk carries a 4-byte 802.1Q tag containing a 12-bit VLAN identifier, which allows up to 4094 VLANs and lets the next switch return every frame to its own VLAN. A device that belongs to a single VLAN connects to an access port, which sends and receives untagged frames.
Without segmentation, all traffic types share one broadcast domain, and a burst of multicast from one system can disturb another. Such interference typically causes intermittent faults that are difficult to trace on a busy show network.
The rule
Each type of show traffic is given its own VLAN so that the traffic of one system cannot disturb another.
Glossary terms
Sources
- IEEE 802.1Q-2022 (Bridges and Bridged Networks) : norme des VLAN et des trames étiquetées · standards.ieee.org
- Comms Express InfoZone, 802.1Q : structure de l'étiquette (TPID 0x8100, 3 bits de priorité, VID 12 bits), 4094 VLAN utilisables · comms-express.com
- Audinate/Yamaha, Dante Network Design Guide, VLAN : segmentation d'un réseau Dante en VLAN · usa.yamaha.com