Thread by @ChainLinkGod

Wrapping up at #SmartCon is a keynote presentation is @bencxr of #Chainlink Labs on Cross-Chain Interoperability

Cross-chain is not just token bridges, but cross-chain communication and programmable bridges with instructions

Bottom layer is transport layer powered by OCR 2.0

Next layer is CCIP to send messages to contracts on other chains

Third layer is the application layer

Transport layer of messages

In the naïve approach, each oracle creates their own transactions

Chainlink Labs developed Off-Chain Reporting (OCR)

Off-chain consensus

$30B+ TVL secured

OCR 2.0 generalizes this capability

100s of high quality nodes coming to feeds

Leader is selected at random

Nodes make observations and send back to leader

Leader receives and broadcasts signed observations

nodes decide if report is sent on-chain

Leader received the signed reports

One node is selected to submit on-chain

If they fail, another node is selected

If that node fails, another node is selected and so on

CCIP is an open-standard that any one can build upon to build cross-chain applications

sendToRemoteChain() takes in input

Then DON calls receiveFromRemoteChain() on other chain

Messaging router contract is deployed on each supported chain

Router will choose the best bridge lane

OCR 2.0 protocol reads the events, check conditions, and then transmit to the other chain

Take turns to transmit report to the other chain

With CCIP, smart contracts can communicate with contracts on other chains without dealing with the underlying complexity

Many use cases

Cross-chain collateral (collateral on chain, borrow on another)
NFT bridges (NFT on one chain, play game on another)
Cross-chain yield

Programmable token bridge is a reference developer focused implementation on top of CCIP

Anyone can build their own bridge on CCIP

destination smart contract can receive both tokens and instructions on what to do with those tokens

bridge can move multiple tokens at a time

Move $USDC from Ethereum to Polygon, trade to $MATIC, deposit it into Aave, all in the same transaction

Only possible on CCIP

Security is key

Want to go not just fast, but go far

High quality nodes
Build the largest quorums of oracle nodes

Anti-Fraud Network

Anti Fraud Network is nodes independent of nodes in the CCIP

Sends heartbeat safety messages

Can trigger an immediate pause of bad behavior of any kind

Also pause when there's a long chain fork, or L2 sequencer problems, external to CCIP

If your protocol handle large amounts, you can join the Anti-Fraud Network

Developers will build things at various levels of the stack

Network efforts of multiple blockchains and increased capacity