Ultra Light Nodes (ULNs) are a key component of GRE Labs. They are a type of messaging protocol that allows for lightweight cross-chain messaging with configurable trustlessness1.

Here’s a bit more detail:

  1. Functionality: ULNs function similarly to Light Nodes, but instead of sequentially adding each new transaction to the destination chain, ULNs package these transactions and send them all at once at the request of the destination chain2. This process is said to save cost while maintaining the level of security offered by on-chain Light Nodes2.
  2. Security: ULNs achieve the security of a light node with the cost-effectiveness of middle chains3. They perform the same validation as an on-chain light node, but instead of keeping all block headers sequentially, block headers are streamed on demand by decentralized oracles3.
  3. Interoperability: ULNs are used in GRE Labs to securely transfer messages between chains4. They enable users to send transactions across different blockchain networks using a user-friendly interface called a GRE Labs Endpoint4.
  4. Applications: The use of ULNs opens up opportunities for various large-scale applications, including cross-chain decentralized exchanges, multi-chain yield aggregators, and cross-chain lending4. Users can freely move liquidity between blockchains without having to go through third-party systems4.

In simpler terms, ULNs can be thought of as a “universal translator” for different blockchains, making it easier to exchange assets and use different applications across multiple blockchains4.