Context

The Symbiosis protocol uses a dedicated Host Chain to facilitate cross-chain operations across supported blockchains. Symbiosis smart contracts and Octopools are deployed on this chain. When a cross-chain swap is initiated, tokens are locked on the source chain, and synthetic tokens (sTokens) are minted on the Host Chain to represent the locked assets. These sTokens can then be exchanged via Octopools for other sTokens backed by assets on other chains, enabling a cross-chain token shift without physically moving tokens between networks. When synthetic tokens are burned, the assets backing them can be released on the corresponding chain.

The Host Chain is where the logical cross-chain transition takes place. The requirements for the Host Chain are straightforward: it must be fast, cheap, and secure.

This architecture was introduced in 2022 when the Symbiosis Protocol went live on Mainnet. Since then, the Host Chain has been Boba BNB — a public Layer 2 (L2) network built on BNB Chain with Optimistic Rollup technology.

Proposal

Migrate the Symbiosis Host Chain from Boba BNB to a dedicated Symbiosis Private Chain — a Layer 2 blockchain built on Ethereum using the Arbitrum Nitro stack. The network will use SIS as its native gas token, bridged from Ethereum. The migration includes the following steps:

• Bridging SIS tokens from Ethereum and using them as the gas token on the new Host Chain
• Deploying and configuring Symbiosis smart contracts on the new Host Chain
• Deploying Octopool smart contracts
• Pausing operations on the existing Host Chain
• Migrating state from the old Host Chain to the new one (including Octopools and core Symbiosis contracts)
• Updating the Relayers Network to interact with the new Host Chain
• Testing cross-chain functionality
• Re-enabling public cross-chain operations via the new Host Chain

Key Points

• The new Host Chain is built using the Arbitrum Nitro stack — a widely adopted and proven Layer 2 framework. As an Ethereum-based rollup, it benefits from Ethereum’s security guarantees, serving as a fallback settlement layer.
• The new Host Chain is optimized and operated by Symbiosis and will be fully tailored for protocol-level cross-chain activity.
• Gas fees on the new Host Chain will be paid in SIS — Symbiosis’ native token — introducing a direct utility for SIS within the protocol infrastructure.
• Processing each transaction on the new Host Chain will consume SIS as gas, with a portion removed from circulation — reinforcing ongoing demand and long-term token value.
• Moving to a self-hosted chain reduces external dependencies, enhancing protocol flexibility, and long-term operational stability.