ENL is Nintendo’s private peer-to-peer framework that’s used by many first-party games, such as Mario Kart 8, Splatoon 2 and Super Mario Maker 2. Check out the pages about PIA for details on how a peer-to-peer session is set up. Once the session is ready, ENL sends all packets through the unreliable protocol.
To transmit game-data, games can register content transporters to ENL. ENL also implements a few content transporters on its own.
A message consists of one or more records, terminated by a record with type 255. No byte swapping is done on the fields. The endianness depends on the system.
Record Header
| Type | Description |
|---|---|
| Uint8 | Record type |
| Uint16 | Record size |
| Bytes | Record data |
| Record Type | Description |
|---|---|
| 0 - 31 | Game-specific |
| 253 | System request info |
| 254 | System information |
| 255 | End record |
System request info
Clients can use this to request a specific record from another client. Every non-zero bit in the record mask indicates a record type that the client wants to receive. The least significant bit represents record type 0, and the most significant bit represents record type 31.
On the Switch, a new field was added that lets a client request a system-record. Here, bit 0 represents record type 253, and bit 1 represents record type 254.
Wii U:
| Type | Description |
|---|---|
| Uint32 | Record mask (games) |
Switch:
| Type | Description |
|---|---|
| Uint32 | Record mask (games) |
| Uint32 | Record mask (system) |
System information
In the tables below, the values of P (maximum number of players) and Q (maximum number of CPUs) are configured by the game.
| Game | P | Q |
|---|---|---|
| Mario Kart 8 | 14 | 10 |
| Splatoon 2 | 10 | 0 |
| Super Mario Maker 2 | 4 | 0 |
Wii U:
| Type | Description |
|---|---|
| Uint32 | Connected AID bitmap |
| Uint32 | Disconnected AID bitmap |
| Uint32 | CPU AID bitmap |
| Uint32 | Received AID bitmap |
| Uint64 | Session time at join |
| Uint32 | Principal id |
| Uint32 | Unknown |
| Uint8 | Is player id table initialized |
| UniqueId (P*2-1) | Player unique ids |
| UniqueId (Q) | CPU unique ids |
| Uint8 | Player id sync unique |
| Uint8 (P) | Player id table |
Switch:
| Type | Description |
|---|---|
| Uint64 | Connected AID bitmap |
| Uint64 | Disconnected AID bitmap |
| Uint64 | CPU AID bitmap |
| Uint64 | Received AID bitmap |
| Uint64 | Session time at join |
| Uint64 | Principal id |
| Uint8 | Is player id table initialized |
| UniqueId (P*2-1) | Player unique ids |
| UniqueId (Q) | CPU unique ids |
| Uint8 | Player id sync unique |
| Uint8 (P) | Player id table |
UniqueId
Wii U:
| Offset | Size | Description |
|---|---|---|
| 0x0 | 4 | [Constant id] |
| 0x4 | 2 | Unknown |
| 0x6 | 2 | Padding (always 0) |
Switch:
| Offset | Size | Description |
|---|---|---|
| 0x0 | 8 | [Constant id] |
| 0x8 | 2 | Unknown |
| 0xA | 6 | Padding (always 0) |