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This guide provides instructions for configuring and managing the IBC Rate Limit module. The module itself only manages the contract address parameter - all rate limiting functionality is handled by the CosmWasm contract.

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Module Configuration

The IBC Rate Limit module has a single parameter that specifies which CosmWasm contract handles rate limiting decisions.
CLI Implementation Issue: The current CLI implementation has a bug that prevents the neutron query rate-limited-ibc params command from working. Use the REST endpoint instead: GET /neutron/ibc-rate-limit/v1beta1/params

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Checking Current Parameters

To check the current contract address parameter via REST: 
curl https://rpc.neutron.org/neutron/ibc-rate-limit/v1beta1/params
Sample response: 
{
  "params": {
    "contract_address": "neutron1abcdef..."
  }
}

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Updating the Contract Address

To update the contract address, governance must submit an update-params proposal: 
neutron tx gov submit-proposal update-params proposal.json --from=<key> --chain-id=<chain-id>
Example proposal.json: 
{
  "title": "IBC Rate Limit Contract Address Update",
  "description": "Update the contract address for the IBC Rate Limit module",
  "messages": [
    {
      "@type": "/neutron.ibcratelimit.v1beta1.MsgUpdateParams",
      "authority": "neutron10d07y265gmmuvt4z0w9aw880jnsr700j7g7ejq",
      "params": {
        "contract_address": "neutron1newaddress..."
      }
    }
  ],
  "deposit": "10000000untrn"
}

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Clearing the Contract Address

To disable rate limiting by clearing the contract address: 
{
  "title": "Disable IBC Rate Limiting",
  "description": "Clear the contract address to disable rate limiting",
  "messages": [
    {
      "@type": "/neutron.ibcratelimit.v1beta1.MsgUpdateParams",
      "authority": "neutron10d07y265gmmuvt4z0w9aw880jnsr700j7g7ejq",
      "params": {
        "contract_address": ""
      }
    }
  ],
  "deposit": "10000000untrn"
}

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Module Behavior

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When Contract Address is Set

When a valid contract address is configured:
  1. Send Operations: The module forwards packet information to the contract via send_packet message
  2. Receive Operations: The module forwards packet information to the contract via recv_packet message
  3. Failed Packets: The module automatically calls the contract’s undo_send function
  4. Rate Limit Exceeded: If the contract returns an error containing “rate limit exceeded”, the transfer is blocked

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When Contract Address is Empty

When no contract address is configured:
  • All IBC transfers proceed normally without any rate limiting
  • The module acts as a pass-through middleware with no additional functionality

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Error Handling

The module handles various error scenarios:

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Rate Limit Exceeded

Error: rate limit exceeded for channel-0 and denom untrn
This error occurs when the contract rejects a transfer due to rate limit constraints.

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Contract Error

Error: contract error: <contract-specific message>
This error occurs when the contract returns an error that doesn’t contain “rate limit exceeded”.

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Bad Revert Events

If the module fails to call the contract’s undo function for failed packets, it emits a bad_revert event: 
{
  "type": "bad_revert",
  "attributes": [
    {"key": "module", "value": "rate-limited-ibc"},
    {"key": "failure_type", "value": "acknowledgment"},
    {"key": "packet", "value": "<packet-data>"},
    {"key": "acknowledgement", "value": "<ack-data>"}
  ]
}

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Contract Requirements

For a CosmWasm contract to work with this module, it must implement the following sudo message handlers:

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Required Sudo Messages

  1. send_packet: Handle outgoing packet information
  2. recv_packet: Handle incoming packet information
  3. undo_send: Handle failed packet reversals
The contract should return an error containing “rate limit exceeded” to block transfers.
Rate Limiting Implementation: The actual rate limiting logic (quotas, time periods, flow tracking, etc.) is entirely contract-specific. The module only provides the packet forwarding mechanism and standardized message interface.

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Monitoring and Debugging

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Module Events

Monitor these events for module-specific issues:
  • bad_revert: Indicates the module failed to notify the contract about a failed packet

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Contract Logs

Monitor contract logs for rate limiting decisions and any contract-specific events.

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Parameter Changes

Monitor governance proposals for contract address updates: 
neutron query gov proposals --status voting_period

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Best Practices

  1. Test Contract Integration: Always test contract behavior in a test environment before governance updates
  2. Monitor Events: Set up monitoring for bad_revert events to detect contract communication issues
  3. Governance Coordination: Coordinate contract address updates with contract deployments
  4. Emergency Procedures: Have procedures ready to clear the contract address if needed to restore transfer functionality
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