The addressing plan of a substation gives each device its IP address and subnet, each type of traffic its VLAN and priority, and each GOOSE and sampled value stream its multicast MAC address and APPID. It is decided at the start of engineering, documented in the SCD file and leaves room for extensions; an improvised plan forces reconfiguring devices in service.
What the addressing plan is
An IEC 61850 substation has tens or hundreds of networked devices: relays, bay controllers, merging units, switches, clocks, gateways, servers and HMIs. Each one needs an identity on the network, and each type of message needs rules so that it reaches only those who use it.
The addressing plan is the document that sets those identities and rules. It is defined at the start of engineering, before the first IED is configured, and it answers five questions:
- Which IP subnets exist and which devices go in each one.
- Which VLANs separate the types of traffic and with what priority each one travels.
- Which multicast MAC address, APPID and VLAN each GOOSE and each sampled value stream uses.
- How devices are named so that the name tells where they are and what they do.
- How much room is left for future bays.
Two worlds on the same network: layer 2 and layer 3
Two classes of traffic coexist in a substation, and the plan treats them differently.
Layer 2 traffic without IP. Classic GOOSE and sampled values are Ethernet multicast. They carry no IP address: they are identified by the destination MAC address, the EtherType (0x88B8 for GOOSE and 0x88BA for SV), the VLAN and the APPID. They do not cross a router.
Layer 3 traffic with IP. MMS between the IEDs and SCADA, engineering and configuration downloads, switch management, network time synchronization, the link to the control center over IEC 60870-5-104 or DNP3 (IEEE 1815) and remote access all use IP addresses and subnets.
The plan assigns addresses in both worlds and defines how they are kept apart.
IP subnets
The usual approach is to use private ranges and split them by function:
- Station network, where the IEDs, the local SCADA and the gateway sit, sometimes divided by voltage level or by area.
- Management network for switches, clocks and network devices, separate from the IED network.
- Engineering network for laptops and configuration servers.
- External link (control center, utility, remote access), always behind an industrial router and firewall.
Each subnet has its mask, its gateway and an allocation rule: for example, one address block per bay with the same order in all of them, so that the address of a relay in a new bay can be worked out without looking up a table. Addresses are static; dynamic assignment is not used on the IED network.
VLAN and priority per type of traffic
The IEEE 802.1Q tag adds a VLAN identifier and a priority from 0 to 7 to the frame. The plan usually separates:
| Traffic | Why it is kept apart | Priority |
|---|---|---|
| Trip and blocking GOOSE | The most time-critical | High |
| Interlocking and status GOOSE | Critical, but less demanding | High or medium |
| Sampled values, per bay or per group | Continuous high-volume stream | High |
| MMS (reports, commands, files) | Client-server over IP | Medium |
| Network management and time sync | Must get through even when the network is loaded | Per design |
| Video and other services | Must not compete with protection | Low, or on a separate network |
The VLAN delivers each multicast stream only to the ports configured in it. Without that separation, every IED receives every GOOSE and every SV stream, and the network can saturate; it is one of the causes of a traffic storm on the substation network. VLANs separate traffic, but they are not a security barrier: traffic between them and to the outside is controlled with a firewall.
Multicast MAC and APPID for GOOSE and SV
IEC 61850 reserves destination address ranges for its layer 2 messages:
- GOOSE: multicast addresses from 01-0C-CD-01-00-00 to 01-0C-CD-01-01-FF and APPID from 0x0000 to 0x3FFF.
- Sampled values: addresses starting with 01-0C-CD-04 and APPID from 0x4000 to 0x7FFF.
The plan assigns a unique combination to each control block. Two GOOSE messages with the same address and APPID in the same VLAN confuse subscribers and switch filters. A practical rule is to tie the APPID to the bay and the IED, just as with IP addresses. You can check the ranges with our free GOOSE and SV address tool.
- 01Inventory of devices and baysIncludes the planned extensions
- 02IP subnets per functionStation, management, engineering and external link
- 03VLANs and prioritiesPer type of traffic and, on the process bus, per bay
- 04MAC, APPID and VLAN of each GOOSE and SVUnique combination per control block
- 05Record in the SCD and the network tableA single source of truth for IEDs, switches and firewall
Device names
The IED name in the SCD, the host name and the physical label should all say the same thing: voltage level, bay, function and whether it is main or backup. A clear name keeps someone from configuring the relay of the wrong bay during an extension. IEC 61850 limits the length and characters of some names, so the convention is set with those restrictions in mind.
Why it is documented in the SCD
The SCD file is the complete description of the system. Its communication section holds the subnets, the IP address of each access point and the address parameters of each GOOSE and SV stream. If the plan lives only in a spreadsheet, sooner or later the SCD and reality drift apart. We explain it in IEC 61850 SCL files.
Switches, clocks and firewalls are not always in the SCD. Their VLAN and filter configuration is documented separately and must match what the SCD says travels through each port.
Room for extensions
Substations grow. The plan leaves free IP blocks, VLAN numbers and APPID ranges for the bays foreseen in the final single-line diagram, so that an extension does not force address changes on devices in service. Changing the IP address or APPID of an energized relay means retesting everything that depends on it.
We help with your network
Tiza Group does the communications engineering of medium, high and extra-high voltage substations and industrial plants, including the addressing plan and its record in the SCD. If a device in service ended up with a duplicate address or outside the plan, we review it through remote relay configuration. Contact us.
Related guides
- VLANs and IEEE 802.1Q priority for GOOSE and SV
- IEC 61850 SCL files: ICD, IID, SSD, SCD, CID and SED
- Substation Ethernet switch
- Substation communication network
- IEC 61850 station bus
- Testing the substation communication network
- Substation network topologies: star, ring and more
- Substation communications by voltage level
- Substation network monitoring: SNMP and syslog
References
- IEC 61850-8-1: mapping to MMS and to ISO/IEC 8802-3 (GOOSE), with its multicast addresses and APPID ranges.
- IEC 61850-9-2: sampled values over ISO/IEC 8802-3.
- IEC 61850-6: SCL configuration language, communication section.
- IEC TR 61850-90-4: network engineering guidelines for power utility automation.
- IEEE 802.1Q: bridges and bridged networks with VLANs.
Frequently asked questions
Do GOOSE and sampled values need an IP address?
No. In their classic form they are layer 2 multicast messages identified by the destination MAC address, the VLAN and the APPID, with no IP address. IP is needed by MMS, engineering, switch management, network time synchronization and the link to the control center.
Where is the addressing plan documented in an IEC 61850 project?
In the communication section of the SCD file, which holds the subnets, the IP address of each access point and the address parameters of each GOOSE and each sampled value stream. Devices that are not IEC 61850, such as switches or firewalls, are documented in a separate table that must match the SCD.
Can the same VLAN be used for all substation traffic?
It works in small networks, but it delivers all multicast to every IED. In high-voltage substations and on the process bus, at least protection traffic, sampled values, client-server traffic and management are separated, each with its own priority.