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SUBMIT A PRSUBMIT AN ISSUElast edit: Sep 04, 2024

Create a Subnet

Note to miners and validators

You do not have to create a subnet to mine or validate on the Bittensor network. See the Checklist for Validating and Mining for information on mining and validating on Bittensor.

Before you deploy your first subnet on the mainchain, we strongly recommend that you follow the below order:

  1. Local first: Create a subnet on your local, and develop and test your incentive mechanism on the local subnet.
  2. Testchain next: After you are satisfied with it, create a subnet on the Bittensor testchain, and test and debug your incentive mechanism on this testchain subnet.
  3. Mainchain last: After completing the above steps, create a subnet on the Bittensor mainchain.
Subnet Creation Limits

Subnet creations are limited to one subnet creation per 7200 blocks (approximately one per day).

Prerequisites​

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

Registering vs creating vs purchasing a slot

In Bittensor, when we say "registering your keys in a subnet", it means purchasing a UID slot in the subnet, and you will then either validate or mine on this UID. This step is also referred to as purchasing a slot. On the other hand, "creating a subnet" will create a subnet and give you its netuid.

Creating a local subnet​

You must also run a local Bittensor blockchain to create and run a local subnet. Running a local blockchain is sometimes synonymously referred to as running on staging. Running a local blockchain spins up two authority nodes locally, not connected to any other Bittensor blockchain nodes either on testchain or mainchain.

Do not run a public subtensor node for a local subnet

Running a local blockchain is different from running a public subtensor node. While a local blockchain node is not connected to any other Bittensor nodes, a public subtensor node will connect to the Bittensor network, testchain, or mainchain as per how you run the subtensor node and sync with the network, giving you your own access point to the Bittensor network. To create a local subnet, do not run a public subtensor; instead, only run a local blockchain.

Step 1. Install and run a local blockchain node​

Follow the Bittensor Subnet Template document and run the below specified steps:

The above steps will install and run a local blockchain node. Furthermore, when built with the --features pow-faucet flag, as instructed in the above Step 5. Initialize, the local blockchain node will provide the faucet feature, which you can use to mint test tokens.

Step 2. Create wallet​

If you have not already done so, create Bittensor wallet(s) using the steps described in the Create Wallet guide.

Step 3. Mint tokens from the faucet​

You will need tokens to register the subnet (which you will create below) on your local blockchain. Run the following command to mint faucet tokens (fake TAO).

btcli wallet faucet --wallet.name <owner-wallet-name> --subtensor.chain_endpoint ws://127.0.0.1:9946

Output:

>> Balance: τ0.000000000 ➡ τ100.000000000

Step 4. 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

Output:

>> 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 registered 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, the subnet with the least staked TAO will be replaced with the newly created subnet, thereby maintaining the total subnet count to 8.

Creating a subnet on testchain​

You do not need to run a local blockchain node to create a testchain subnet. Instead, your subnet will connect to the Bittensor testchain.

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

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

Step 1. Create wallet​

If you have not already done so, create Bittensor wallet(s) using the steps described in the Create Wallet guide.

Step 2. Get the current price​

btcli subnet lock_cost --subtensor.network test

Output:

>> Subnet lock cost: τ100.000000000

Step 3. Get faucet tokens​

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

Step 4. Create the subnet​

Create your new subnet on the testchain using the test TAO you received from the previous step. This will create a new subnet on the testchain and give you its owner permissions.

Your test TAO is returned when the subnet is deregistered

Subnet creation (subnet registration) on the testchain costs test TAO. You will get this test TAO back when the subnet is deregistered.

Run the create subnet command on the testchain.

btcli subnet create --subtensor.network test

Output:

# Enter the owner wallet name, which gives the coldkey permissions to define running hyperparameters later.
>> 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​

You do not need to run a local blockchain node to create a subnet on the mainchain. Instead, your subnet will connect to the Bittensor mainchain. Follow the below steps.

Alert: Minimum required TAO

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

Step 1. Create wallet​

If you have not already done so, create Bittensor wallet(s) using the steps described in the Create Wallet guide.

Step 2. Get the current price​

The code below shows how to get the current price of creating a subnet on the mainchain (when the --subtensor.network option is not used, then the btcli will default to the mainchain).

btcli subnet lock_cost

Output:

>> Subnet lock cost: τ100.000000000

Step 3. Create the subnet​

Your TAO is returned when the subnet is deregistered

Subnet creation (subnet registration) on the mainchain costs real TAO. You will get this TAO back when the subnet is deregistered.

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

btcli subnet create

Output:

>> 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.

Immunity period for a subnet​

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

  • Subnets are competitive, even though new and additional subnets are routinely created in the Bittensor network. As a result, subnet performance is continuously monitored, poor-performing subnets are deregistered, and the registration cost is 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 the subnet's performance. See Emissions.

  • Furthermore, any subnet has an immunity period of 7 * 7200 blocks, which is seven 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 at risk of deregistered.

  • However, at the end of this immunity period, if the subnet's emissions are the lowest among all the 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, followed by the second oldest, and so on.

A newly created subnet starts with zero emission

Subnet deregistration​

poor-performing subnets risk deregistration

Ensure your subnet's performance is high, or it risks being deregistered. Also, see the above section on Immunity period for a subnet.

When a subnet is deregistered, all its UIDs are also deregistered along with it. As a result, the subnet's subnet miners and subnet validators are also deregistered. The new subnet at this netuid starts afresh, and any subnet miners and subnet validators for this new subnet must register using the standard registration step described in Register.