Device Level Ring Topology

Device Level Ring (DLR) is an EtherNet/IP™ protocol that is defined by ODVA. DLR provides a means to detect, manage, and recover from a single fault in a ring-based network.
A DLR network includes the following types of ring nodes.
DLR Nodes
Node
Description
Ring supervisor
A ring supervisor provides these functions:
  • Manages traffic on the DLR network
  • Collects diagnostic information for the network
A DLR network requires at least one node to be configured as ring supervisor. By default, the supervisor function is disabled on supervisor-capable devices.
Ring participants
Ring participants provide these functions:
  • Process data that is transmitted over the network.
  • Pass on the data to the next node on the network.
  • Report fault locations to the active ring supervisor.
When a fault occurs on the DLR network, ring participants reconfigure themselves and relearn the network topology.
Redundant gateways (optional)
Redundant gateways are multiple switches that connect to a DLR network and also connect together through the rest of the network. Redundant gateways provide DLR network resiliency to the rest of the network.
Depending on their firmware capabilities, both devices and switches can operate as supervisors or ring nodes on a DLR network. Only some devices, such as switches, can operate as redundant gateways.
For more information about DLR, see the EtherNet/IP Device Level Ring Application Technique, publication ENET-AT007.
DLR Network Topology Example
image shows the controller in a Device Level Ring network topology.
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