How bridges are categorised: trust assumptions As well as the different token transfer methods, we also need to consider different trust assumptions, with each bridge ranging from strong trustworthiness (bad) to weak trustworthiness (good).The various levels of trustworthiness can be categorised as follows:Centralised bridges. Example: The Binance-to-Arbitrum bridge. Validator/multi-sig bridges. Wormhole, Axelar, Connext. State proof bridges. StarkEx to Ethereum, ZKSync to Ethereum, Nomad, Hop, Axelar, and Mina. Protocol-level bridges. Cosmos IBC.Centralised Bridges Centralised bridges often rely on a single party or signatory to process and control the flow of funds. For example, when you deposit to Binance from Arbitrum, you are relying on Binance to credit your account with the funds you deposited to their smart contract. Collateral is needed on both sides of the equation (both Binance and Binance’s Arbitrum smart contract) in order to facilitate transfers. There is also no failsafe if the operator were to go offline. Centralised bridges solve a short-term need for quick transfers. However they are opaque and not scalable or censorship-resistant, so are limited to simple bridging. Validator / Multi-sig Based Solutions These types of bridges are more secure than centralised bridges, requiring weaker trust assumptions. Several different types of agents/actors are incentivised to watch both sides of the bridge and act as oracles to report on the deposits/withdrawals made. However, a certain element of trust is required in the validator set, which in most cases are little more than a basic multi-sig. Collateral is still required on both sides of the bridge, which raises costs, particularly for less commonly used bridge paths, and are therefore either supported by large entities, or require expensive liquidity mining programs to run. Here’s an example of the . , SonicOS Enhanced firmware versions 4.0 and higher includes L2 (Layer 2) Bridge Mode, a new method of unobtrusively integrating a SonicWall security appliance into any Ethernet network.L2 Bridge Mode is ostensibly similar to SonicOS Enhanced Transparent Mode in that it enables a SonicWall security appliance to share a common subnet across two interfaces, and to perform Stateful and deep-packet , How bridges are categorised: transfer type Bridges can be categorised by both transfer type (simple to complex), and trust assumptions (strong to weak). Let’s deal with transfer types first. Arjun Chand from Li.Fi, a bridge aggregation protocol, identifies three main types of bridges based on different transfer types. This can be further expanded to five types, although the design space is .