Two protection IEDs from different manufacturers arrive with the same default GOOSE address. How the clash is found in the SCD, why it matters, and how to reassign the addresses without breaking subscriptions.
| System | 132/33 kV substation SCD, one station bus subnetwork |
| Publisher 1 | Line protection IED F01_PROT, GOOSE control block gcbTrip |
| Publisher 2 | Transformer protection IED T01_PROT (different manufacturer), GOOSE control block gcbTrip |
| Address in both ICD files | APPID 0001, MAC 01-0C-CD-01-00-01, VLAN-ID 000, priority 4 |
| Subscriber | Busbar protection IED BB_PROT subscribes to both trip messages |
Manufacturers' ICD files often ship with the same first address. The system integrator must make every GOOSE stream unique when the SCD is assembled.
Open the SCD and run the communication checks. Both GSE elements in the Communication section carry the same address, so validation reports:
The MAC address is reported as an error because two publishers on one multicast address cannot be told apart by switches that filter on MAC. The APPID is a warning because subscribers filter on it, but the GoID and data set can still distinguish the streams in some IEDs.
A subscriber that filters on MAC and APPID receives both streams as if they were one. Depending on the IED, it may reject both (because the GoID or data set does not match what it expects) or accept the wrong one. Either way, the busbar protection may not see a breaker-fail trip from the transformer IED.
Keep each value inside the ranges of IEC 61850-8-1 and unique on the subnetwork.
| Publisher | MAC address | APPID | VLAN-ID / priority |
|---|---|---|---|
| F01_PROT gcbTrip | 01-0C-CD-01-00-01 | 0001 | 000 / 4 (unchanged) |
| T01_PROT gcbTrip | 01-0C-CD-01-00-02 | 0002 | 000 / 4 |
GOOSE MAC addresses run from 01-0C-CD-01-00-00 to 01-0C-CD-01-01-FF. GOOSE APPIDs run from 0000 to 3FFF, or 8000 to BFFF for Type 1A trip GOOSE where all the IEDs support that range.
Change the T01_PROT GSE address in the Communication section (or use the editor's automatic address assignment for all control blocks), then run validation again.
Export the CID files for both publishers and for the subscriber, because the subscriber's configuration also holds the expected address of each stream. Load them with each manufacturer's tool and confirm with a network analyser that two separate GOOSE streams are present.
| Check | Requirement | Actual | Status |
|---|---|---|---|
| MAC address unique on subnetwork | Each GOOSE stream has its own multicast MAC | Was duplicated; now 01-0C-CD-01-00-01 and 01-0C-CD-01-00-02 | ✓ PASS |
| APPID unique on subnetwork | Each GOOSE stream has its own APPID | Was duplicated; now 0001 and 0002 | ✓ PASS |
| Values inside IEC 61850-8-1 ranges | MAC 01-0C-CD-01-00-00…01-FF, APPID 0000–3FFF | Both inside range | ✓ PASS |
Key insight: Address clashes are a system-integration problem, not a fault in either IED: each ICD file is correct on its own. Checking the whole SCD for duplicates is the only place they show up before site testing.
Every input in this example is editable in the live calculator — no signup needed.
Open IEC 61850 SCL Editor (SCL Studio) calculator →No. The APPID is a 16-bit value in the Ethernet frame used for fast filtering. The GoID (appID attribute of the GSEControl) is a text identifier carried inside the GOOSE message.
No. VLANs separate traffic on the network; uniqueness of each stream comes from the MAC address and APPID. Many projects put all protection GOOSE on one VLAN.
Yes. The subscriber filters on the expected address, so its configuration must be updated and reloaded as well.