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Cross-chain Communication

How much is cross-chain transfer fee?

The total cost of transfer from BC to BSC is composed of 2 parts:

  • Fee for executing bridge transfer-out transaction is 0.004BNB, pay validators on BNB Beacon Chain

  • Fee for BSC-relayers 0.004BNB. it will cover the fees of calling TokenHub Contract on BSC.

The total cost of transfer from BSC to BC is composed of 2 parts:

  • Fee for Oracle-relayers 0.004BNB, pay for BSC relayers

  • Call TokenHub Contract: You need to pay BNB for calling smart-contract on BSC, this transaction is metered by gas, which is a global parameter. At the moment, you need to pay about 0.0005BNB ~ 0.0015BNB.

What's is a BSC relayer?

BSC relayer monitors cross chain packages on BNB Beacon Chain, builds and broadcasts transactions to BSC to deliver these packages, which is the key of cross chain communication from BNB Beacon Chain to BSC.

What's is an Oracle relayer?

Oracle Relayer watches the state change of BNB Smart Chain. Once it catches Cross-Chain Communication Events, it will submit to vote for the requests. After Oracle Relayers from ⅔ of the voting power of BC validators vote for the changes, the cross-chain actions will be performed. Only validators of BNB Beacon Chain are eligible to run Oracle relayers.

What's an oracle?

In blockchain network, an oracle refers to the element that connects smart contracts with data from the outside world. In the network of BNB Smart Chain, the execution of the transaction wil emit Events, and such events can be packaged and relayed onto BC. In this way, BC will get updates about changes of BSC.

How to send cross-chain transfer?

You can use Binance Extension Wallet or

use Trust wallet