Appendix 4: Ring Protection; Requirements And Limitations; Definitions - Acuity Brands Lighting Pathway VIA 12 Series User Manual

APPENDIX 4: RING PROTECTION

Ethernet wiring schemes are based on a 'star'-wiring topology. Ring (or loop) data wiring – where the last device in a chain is
wired back to the first device – is forbidden. Only one data path between any two devices is allowed.
But star-wiring layouts are prone to single point failures. Unlike DMX512 transmission, passive data 'thru' connections are not
possible with Ethernet, which means there is no redundancy under normal operation. A severed cable or power loss to a switch
can mean the loss of some or even all show control.
EAPS (Ethernet Automatic Protection Switching) allows the deliberate – and designed – use of a ring wiring system for
Ethernet communications. When in this mode, VIA switches ignore data traffic on one segment of the ring, while monitoring the
integrity of the remaining connections. If an interruption is detected, the unused ring segment is activated and full communication
is restored. Fail-over time is between 50 and 75 milliseconds, or two to four DMX packets.

REQUIREMENTS AND LIMITATIONS

VLANs must be enabled to use Ring Protection. The mode uses a dedicated VLAN to monitor the integrity of the ring, called
a Control VLAN. All switches must use the same Control VLAN. By default, VLAN 4095 is used. This does not mean your
VLAN range needs to extend to 4095. Typically an entertainment network may use 1-3 or 1-10 VLANs.
Only the last 4 ports on the switch (ports 11-14) may be used with this feature.
If the ring is intact, the front display of the VIA12 will say "Ring is healthy". If the Ring fails, the front menu will report as such
and flash the backlight of the display.
Ring Protection works with Pathway VIA switches only. Switches from other manufacturers can co-exist on the network, but
should not be placed in-line with the ring.

DEFINITIONS

Master switch monitors the integrity of communications. Only one switch on the network may be configured as the master. If
choice is available, the least busy switch, with the most reliable power source, preferably on an uninterruptible power supply,
should be chosen as the master.
Transit switches receive and forward the ring monitoring packets. All switches other than the Master must be set as transit
switches.
NOTE: Ring Protection wiring topology is not structured. A Primary port on one switch may be connected to a Secondary
port on the next switch – any arrangement is acceptable. The link status in Pathscape will either be "Forwarding all traffic"
or "Blocked by EAPS".
Primary Port is the main (active) UPLINK connection link on the Master switch, joining to the rest of the network. All transit
switches must also have one port configured as the primary. Only ports 11 through 14 are available to be used as the primary
port. If using copper, typically port 11 will be primary and 12 will be secondary. If using fiber, port 13 is primary and port 14
is secondary.
Secondary Port is an UPLINK port "ignored" (logically blocked) by the Master switch to break the ring topology. All transit
switches also must have one port configured as the secondary port. The secondary port is actively used on transit switches.
Only ports 11 through 14 are available to be used as the secondary port.
69
VIA12 [6750, 6750-P, 6752-P, 6754-P] - Manual REV 1.0 • June 2020