The need: preserve machine-to-machine exchanges
Some industrial machines rely on local discovery, broadcasts or Ethernet exchanges that do not cross a routed network. The requirement is to preserve this logical proximity while distributing equipment across physical sites.
Architecture: carry layer 2 across the WAN
Gateways transport the industrial Ethernet segment over WAN links, providing a shared layer-2 domain for the machines. Only the VLANs needed by the equipment are extended; administration networks and other workloads remain separate. Transport needs authentication and encryption when links are not trusted.
Multiple links, controlled continuity
WAN paths can differ in bandwidth, latency and MTU. Sizing accounts for encapsulation and actual traffic. Failover must avoid layer-2 loops, problematic asymmetric paths and repeated MAC address moves. Link failure and recovery behaviour are part of acceptance testing.
Validate industrial behaviour
Extending a LAN does not remove distance: latency, jitter and packet loss remain those of the WAN. Machine timing tolerances must be measured, discovery mechanisms verified and broadcast propagation bounded. Machine safety functions and real-time control loops require their own validation; Ethernet continuity alone is not sufficient.
Operate a distributed topology
Monitoring correlates tunnel and link status, loss, latency and equipment events. VLAN and path maps, traffic limits and rollback procedures keep the network scope understandable despite its geographic distribution.
Key considerations
- Targeted L2 extension
- Multiple WAN links and failover
- MTU, latency and jitter
- Segmentation and monitoring