Pathway Connectivity
VIA 12 Manual
V3 – April 2015
20
Appendix 3: 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.
Ring Protection allows the deliberate – and designed – use of a ring wiring system for
Ethernet communications. When in this mode, VIA 12 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. By default, VLAN 4095 is used.
Only the rear ports (ports 11 through 14) on the VIA 12 may be used with this feature.
Ring Protection works with Pathport VIA 12 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 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.
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.
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.
Control VLAN is a unique VLAN ID dedicated to monitoring the health of the network.
All switches must use the same control VLAN. The default is VLAN ID 4095.
