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SUBMIT AN ISSUElast edit: Feb 28, 2024

Create a Subnet

Before you create your first subnet, we strongly recommend that you follow the below order:

  1. First create a subnet on your local, and develop and test your incentive mechanism on the local subnet.
  2. After you are satisfied with it, next create a subnet on the Bittensor testchain, and test and debug your incentive mechanism on this testchain subnet.
  3. Finally, only after you completed the above steps, create a subnet on the Bittensor mainchain.

Immunity period for a subnet​

The notion of immunity_period applies to a subnet also. It works like this:

  • Subnets are competitive and only 32 subnet slots exist in the Bittensor network. As a result, subnet performance is continously monitored, poor-performing subnets are deregistered and the registration cost will be returned to the deregistered subnet owner.

  • A subnet's performance is measured using the emissions earned by the subnet: The lower the emission earned by the subnet, the poorer is the subnet's performance. See Emissions.

  • Furthermore, any subnet has an immunity period of 7 * 7200 blocks, which is 7 days. See the line of code that defines SubtensorInitialNetworkImmunity. This initial network immunity period starts when the subnet is created and its netuid is issued to the subnet owner. During this immunity period the subnet is not under any risk of being deregistered.

  • However, at the end of this immunity period, if the subnet's emissions are the lowest among all the 32 subnets, then this subnet will be deregistered when a new subnet registration request arrives. If there are several subnets with the lowest emission then the oldest subnet among the lowest will be deregistered first, and then the second oldest, and so on.

Prerequisites​

To create a subnet, whether locally or on testchain or on mainchain, make sure that:

Registering vs creating vs purchasing a slot

Registering a subnet will create the subnet. This step is also referred as purchasing a slot.

Creating a local subnet (staging)​

Local blockchain vs local subtensor node​

Running a local blockchain is sometimes synonymously referred as running on staging. This is different from running a local subtensor node that connects to the Bittensor mainchain.

A local subtensor node will connect to the mainchain and sync with the mainchain, giving you your own access point to the mainchain.

Running a local blockchain spins up two authority nodes locally, not connected to any other nodes or testchain or mainchain. The below instructions are applicable when you want to create a local subnet together with creating a local blockchain.

Step 1. Mint tokens from faucet​

You will need tokens to register a subnet on your local. Run the following command to mint faucet tokens (fake TAO).

# Mint tokens for the subnet owner
btcli wallet faucet --wallet.name <owner-wallet-name> --subtensor.chain_endpoint ws://127.0.0.1:9946 
>> Balance: τ0.000000000 ➡ τ100.000000000

Step 2. Create the subnet​

Run the below command to create a new subnet on your local chain. The cost will be exactly τ100.000000000 for the first subnet you create.

btcli subnet create --wallet.name owner --subtensor.chain_endpoint ws://127.0.0.1:9946 
>> Your balance is: τ200.000000000
>> Do you want to register a subnet for τ100.000000000? [y/n]: 
>> Enter password to unlock key: [YOUR_PASSWORD]
>> ✅ Registered subnetwork with netuid: 1

The local chain will now have a default netuid of 1. A second registration will create netuid 2 and so on until you reach the subnet limit of 8. If you create the 9th subnet, then the subnet with the least staked TAO will be replaced with the newly create subnet, thereby maintaining total subnet count to 8.

Creating a subnet on testchain​

Creating a subnet on the testchain is competitive. Though you will only use the faucet TAO tokens for testchain, the cost to create a subnet is determined by the rate at which new subnets are being registered onto the testchain.

By default you must have at least 100 testnet TAO in your owner wallet to create a subnet. However the exact amount will fluctuate based on demand. Follow the below steps.

Step 1. Get the current price​

btcli subnet lock_cost --subtensor.network test
>> Subnet lock cost: τ100.000000000

Step 2. Get faucet tokens​

Faucet is disabled on the testchain. Hence, if you don't have sufficient faucet tokens, ask the Bittensor Discord community for faucet tokens.

Step 3. Create the subnet​

Register (i.e., create) your new subnet on the testchain using the test TAO you minted from the previous step. This will create a new subnet on the testchain and give you the owner permissions to it. This step is sometimes referred as purchasing a slot.

Your TAO is returned when subnet is deregistered

Subnet registration costs TAO. You will get this TAO back when the subnet is deregistered.

# Run the register subnetwork command on the testchain.
btcli subnet create --subtensor.network test 
# Enter the owner wallet name which gives permissions to the coldkey to later define running hyper parameters.
>> Enter wallet name (default): owner # Enter your owner wallet name
>> Enter password to unlock key: # Enter your wallet password.
>> Register subnet? [y/n]: <y/n> # Select yes (y)
>> Registering subnet...
✅ Registered subnetwork with netuid: 1 # Your subnet netuid will show here, save this for later.

Creating a subnet on mainchain​

Alert: Minimum required TAO

Creating a subnet on mainnet is competitive and the cost is determined by the rate at which new networks are being registered onto the chain. By default you must have at least 100 TAO in your owner wallet to create a subnetwork. However the exact amount will fluctuate based on demand.

Step 1. Get the current price​

The code below shows how to get the current price of creating a subnetwork.

btcli subnet lock_cost
>> Subnet lock cost: τ100.000000000

Step 2. Create the subnet​

Your TAO is returned when subnet is deregistered

Subnet registration costs TAO. You will get this TAO back when the subnet is deregistered.

Use the below command to register a new subnet on the mainchain.

# Run the below command to create a subnet on the mainchain (default is mainchain)
btcli subnet create
>> Enter wallet name (default): owner # Enter your owner wallet name
>> Enter password to unlock key: # Enter your wallet password.
>> Register subnet? [y/n]: <y/n> # Select yes (y)
>> Registering subnet...
✅ Registered subnetwork with netuid: 1 # Your subnet netuid will show here, save this for later.
poor-performing subnets risk deregistration

Finally, make sure that your subnet's performance is high, or else the subnet will risk being deregistered. See the above section on Immunity period for a subnet.