> ## Documentation Index > Fetch the complete documentation index at: https://docs.layerzero.network/llms.txt > Use this file to discover all available pages before exploring further. # DVN and Executor Configuration on Stellar > Configure the Decentralized Verifier Network (DVN) and Executor for your LayerZero OApp on Stellar. Set up message verification, execution, and security parameters. This guide covers how to configure the security and execution stack for your LayerZero OApp or OFT on Stellar. ## Overview Configuring a LayerZero application on Stellar involves these steps: 1. **Configure DVN** -- set verification parameters (required DVNs, optional DVNs, confirmations) 2. **Configure Executor** -- set execution parameters (max message size, executor address) 3. **Set Enforced Options** -- define minimum execution options per destination ## DVN Configuration DVNs (Decentralized Verifier Networks) verify crosschain messages. Configuration is done via the ULN-302 message library through the endpoint's `set_config` function. ### ULN Config Structure ```rust wrap theme={null} struct UlnConfig { confirmations: u64, // Block confirmations required required_dvns: Vec
, // DVNs that MUST ALL verify optional_dvns: Vec
, // Pool of optional DVNs optional_dvn_threshold: u32, // How many optional DVNs must verify } ``` | Field | Description | Default Behavior | | ------------------------ | -------------------------------------------------------- | -------------------------------------------------- | | `confirmations` | Source chain block confirmations before DVN verification | Uses default if `use_default_confirmations = true` | | `required_dvns` | All listed DVNs must verify every message | Uses default if `use_default_required_dvns = true` | | `optional_dvns` | Pool of additional DVNs | Uses default if `use_default_optional_dvns = true` | | `optional_dvn_threshold` | Minimum optional DVNs that must verify | Must be ≤ `optional_dvns.len()` | The effective config must have at least one DVN — either `required_dvns` must be non-empty, or `optional_dvn_threshold` must be greater than 0. ### Configure Send DVN Set the DVN configuration for outbound messages: ```bash wrap theme={null} stellar contract invoke \ --id \ --network testnet \ --source my-account \ -- \ set_config \ --caller \ --oapp \ --lib \ --params '[{"eid": , "config_type": 2, "config": ""}]' ``` Config type `2` = `CONFIG_TYPE_SEND_ULN`. ### Configure Receive DVN Set the DVN configuration for inbound messages: ```bash wrap theme={null} stellar contract invoke \ --id \ --network testnet \ --source my-account \ -- \ set_config \ --caller \ --oapp \ --lib \ --params '[{"eid": , "config_type": 3, "config": ""}]' ``` Config type `3` = `CONFIG_TYPE_RECEIVE_ULN`. ### OApp ULN Config When setting per-OApp config, use `OAppUlnConfig` which includes flags to fall back to defaults: ```rust wrap theme={null} struct OAppUlnConfig { use_default_confirmations: bool, use_default_required_dvns: bool, use_default_optional_dvns: bool, uln_config: UlnConfig, } ``` Set a field's `use_default_*` flag to `true` to inherit the network-wide default for that field, even if you customize other fields. When a `use_default_*` flag is `true`, the corresponding config values **must** be zero or empty. For example, if `use_default_confirmations` is `true`, `confirmations` must be `0`. If `use_default_required_dvns` is `true`, `required_dvns` must be empty. Violating this constraint will cause the transaction to fail. ## Executor Configuration The Executor delivers verified messages to the destination OApp. Configuration is also done via `set_config`: ```rust wrap theme={null} struct OAppExecutorConfig { max_message_size: u32, // 0 = use default executor: Option
, // None = use default } ``` ```bash wrap theme={null} stellar contract invoke \ --id \ --network testnet \ --source my-account \ -- \ set_config \ --caller \ --oapp \ --lib \ --params '[{"eid": , "config_type": 1, "config": ""}]' ``` Config type `1` = `CONFIG_TYPE_EXECUTOR`. The `config` field in `SetConfigParam` is XDR-encoded bytes. Soroban contract types (`OAppUlnConfig`, `OAppExecutorConfig`) must be serialized to XDR before passing to `set_config`. Use the Stellar SDK's `toXDR()` method or the `stellar-xdr` Rust crate to encode these structs. ## Setting Enforced Options Enforced options define the **minimum execution parameters** for outbound messages. They are combined with any caller-provided options: ```bash wrap theme={null} stellar contract invoke \ --id \ --network testnet \ --source my-account \ -- \ set_enforced_options \ --options '[{"eid": , "msg_type": 1, "options": ""}]' \ --operator ``` The `options` field is `Option` — pass `null` to remove enforced options for a given eid/msg\_type combination. | Message Type | Description | | ------------ | ----------------------------------------------------------------------- | | `1` | `SEND` -- standard message (OFT: token transfer) | | `2` | `SEND_AND_CALL` -- message with compose (OFT: token transfer + compose) | Always set enforced options for each destination. Without them, messages may fail due to insufficient gas on the destination chain. For `SEND_AND_CALL` (type 2), ensure the gas limit accounts for the compose execution. ## Gas Options Example When setting enforced options or passing `extra_options` in a send, you must specify the gas for `lzReceive` on the destination chain. The following examples use the standard LayerZero Type 3 encoding: | Operation | Example Gas | Options Hex | | --------------------------------- | ----------- | ---------------------------------------------- | | Basic `lz_receive` (OFT transfer) | 200,000 | `00030100110100000000000000000000000000030d40` | | `lz_receive` + `lz_compose` | 500,000 | `0003010011010000000000000000000000000007a120` | The options format is: `0x0003` (Type 3 header) + `01` (executor worker ID) + `0011` (length = 17 bytes) + `01` (lzReceive option type) + gas as `uint128`. Sending with **empty `extra_options`** and no enforced options will cause the send to fail with error `#1114` at the message library level. Always include executor options specifying the gas for `lzReceive` on the destination. ## Reading Configuration Query the current configuration for your OApp: ```bash wrap theme={null} # Get effective send ULN config stellar contract invoke \ --id \ --network testnet \ --source my-account \ -- \ effective_send_uln_config \ --sender \ --dst_eid ``` ```bash wrap theme={null} # Get effective receive ULN config stellar contract invoke \ --id \ --network testnet \ --source my-account \ -- \ effective_receive_uln_config \ --receiver \ --src_eid ``` ```bash wrap theme={null} # Get effective executor config stellar contract invoke \ --id \ --network testnet \ --source my-account \ -- \ effective_executor_config \ --sender \ --dst_eid ``` ## Next Steps * **[Technical Overview](/v2/developers/stellar/technical-overview)**: Understand how DVN verification and executor delivery work end-to-end. * **[Troubleshooting](/v2/developers/stellar/troubleshooting/common-errors)**: Common configuration errors and solutions.