The protocol fee is a fixed % of the primary asset of the chain charged for bridging assets from one chain to another. The fee varies for the different supported chains and can range from 0.1%-0.5%
A specified amount of BRDG token is required for adding a token to the token bridge. The formula for deriving the BRDG amount is f*n Where F is the fixed amount of BRDG token per supported chains and n is the number of network supported.
For example: if f is 5000 BRDG and a token issuer want to take the token to 4 different chains, the the fee would be 5000 * 4 = 20,000 BRDG token. 50% of the fee collect is burned and the remaining is used to incentivise the oracles and registrars.
The fee controller manages the fee structure of the protocol on chain. The fee controller has 3 fee incentive mechanism controlled by the bridge governance:
User Fee Exemption: Fee controller may turn off fees by in which case a user bridges assets with zero fees.
Bridge Token Holding Incentive: Fee controller may incentivize user by enabling a minimum BRDG token holding requirement. In this case if a user holds the required minimum BRDG token during a bridging transaction, an incentive in the form of reduced fees or rebate would be applied to the overall transaction fee.
Asset Specific Incentive: The fee for a specific asset on bridge can be updated with an incentive mechanism. In this case, when a user bridges X asset, they have a specific incentivize. But if they bridge Y asset, such incentive is not applied.