Local Area Network Emulation Service¶
This service provides local area network emulation (LANE) for its connected clients. Every client is given a unique address within the address space available to the server. For example, if the server was providing Ethernet Local Area Network Emulation (ELANE) then each client would be given an Ethernet 6-octet address.
The size of the address space is a configuration property of the server. It must be at least 1-octet which would be similar to an MS/TP or ARCNET LAN, and addresses longer than 6-octets may not be supported by BACnet devices.
The server is also configured with a BACnet network number that is unique in the BACnet intranet. It may be a standalone server which is not functioning as a router. If it is functioning as a router, then at least one of the addresses in the address space available to the server will be reserved to be the address of the router to the BACnet intranet.
After authentication, if the server does not provide the LANE Service then it will send a Service Request Result with the error code NO_LANE_SERVICE.
Note
This is now more commonly referred to as a virtual network and the addresses assigned by the server are virtual MAC addresses.
Protocol Data Units¶
Packets from the LANE server to the connected clients will have the SNET/SLEN/SADR fields present. The DNET/DLEN/DADR fields may also be present if the packet was broadcast, in this case the DLEN will always be zero and the DADR empty octet string.
Packets from a client to its connected server will have the DNET/DLEN/DADR fields present.
LANE Client to Server Unicast Request¶
This packet is sent by a client to the server to request that the server send the request to a BACnet address on behalf of the client. The request payload is restricted to unicast messages.
The DNET/DLEN/DADR fields of the NPCI will be present, even if the destination is the BACnet network being emulated by the server.
| Field | Size | Description |
|---|---|---|
| BSLV Type | 1-octet | Streaming BACnet (value = X‘82’) |
| BSLV Function | 1-octet | LANE Client to Server Unicast Request (value = X‘0B’) |
| BSLV Length | 2-octets | Length |
| Payload | variable | Application PDU |
LANE Client to Server Broadcast Request¶
This packet is sent by a client to the server to request that the server broadcast the request on the network emulated by the server in the case of a local broadcast or global broadcast message, or in the case of a remote network broadcast, send the request as a unicast message to the router responsible for the destination network. The request payload is restricted to broadcast messages.
The DNET/DLEN/DADR fields of the NPCI will be present. If the destination is to be considered a local broadcast by the LANE server, then the DNET will be the network emulated by server. In all cases the DLEN will be zero and the DADR will be the empty octet string.
| Field | Size | Description |
|---|---|---|
| BSLV Type | 1-octet | Streaming BACnet (value = X‘82’) |
| BSLV Function | 1-octet | LANE Client to Server Broadcast Request (value = X‘0C’) |
| BSLV Length | 2-octets | Length |
| Payload | variable | Application PDU |
LANE Server to Client Unicast Request¶
This packet is a forwarded copy of a unicast message received by the server to the client. The request payload is restricted to unicast messages.
The SNET/SLEN/SADR fields of the NPCI will be present, even if the destination is the same BACnet network emulated by the server. The DNET/DLEN/DADR fields of the NPCI will be absent.
| Field | Size | Description |
|---|---|---|
| BSLV Type | 1-octet | Streaming BACnet (value = X‘82’) |
| BSLV Function | 1-octet | LANE Server to Client Unicast Request (value = X‘0D’) |
| BSLV Length | 2-octets | Length |
| Payload | variable | Application PDU |
LANE Server to Client Broadcast Request¶
This packet is a forwarded copy of a broadcast message received by the server to the client. The request payload is restricted to broadcast messages.
The SNET/SLEN/SADR fields of the NPCI will be present, even if the destination is on the same BACnet network emulated by server.
The DNET/DLEN/DADR fields of the NPCI will be present. If the destination was a local broadcast when it was received by the server, then the DNET will be the network emulated by the server. In all cases the DLEN will be zero and the DADR will be the empty octet string.
| Field | Size | Description |
|---|---|---|
| BSLV Type | 1-octet | Streaming BACnet (value = X‘82’) |
| BSLV Function | 1-octet | LANE Server to Client Broadcast Request (value = X‘0E’) |
| BSLV Length | 2-octets | Length |
| Payload | variable | Application PDU |