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Bridge Fee

How is the fee calculated?

In cBridge v2, the bridge fee is calculated as
Fee = Base Fee + Liquidity Fee
The Base Fee is paid to cover the gas cost for sending funds on the destination chain. Liquidity Fee is paid to the cBridge liquidity providers and State Guardian Network (SGN) in return to their services.
The Liquidity Fee is proportional to the transfer amount (after bridge rate conversion) and the fee percentage is:
  • For transfers from L2 roll-up chains (Arbitrum/Optimism/Boba/Metis), the liquidity fee percentage is 0.1%-0.5%
  • For transfers from Fantom to Ethereum, the liquidity fee percentage is 0.1%
  • For all other transfers, the liquidity fee percentage is 0.04%
The above fee schedule applies to pool-based cross-chain transfers. For canonical token bridges (mint & burn), see here for the introduction.

Bridge Rate

How is the bridge rate calculated?

For most bridge pairs under the pool-based token bridge model, the bridge rate is calculated based on the StableSwap AMM curve. You may refer to the StableSwap whitepaper for details. In most cases, the bridge rate is close to 1 unless there is a significant liquidity imbalance between the source chain and the destination chain. Note that if your transfer helps rebalance the system (e.g., sending from a low-balance chain to a high-balance chain), you may even get more tokens after bridging!
For some bridge pairs, the AMM curve is not used and the bridge rate is fixed to 1:1.
For canonical token bridges (mint & burn), the bridge rate is fixed to 1:1.

Contract Addresses

Where can I find the contract addresses used in cBridge?

Please refer to this page for the list of contract addresses used in cBridge.

What are the token addresses on different chains?

Please refer to this page for the list of token addresses on different chains.

User Operations

How long does it take to complete a cross-chain transfer?

Most of the cross-chain transfers take 5-20 minutes to complete. Cross-chain transfer with an amount larger than $120,000 may take a few hours during the beta release stage.

My cross-chain transfer has been stuck for more than 30 minutes. What should I do?

If your transfer is stuck in the “Submitting” status, please check if your transfer has been confirmed on the source chain. If the transfer is not yet confirmed on the source chain, you can speed up the transfer by increasing your gas price; otherwise, feel free to contact customer support along with your transaction hash on the source chain.
If your transfer is stuck in the “Waiting for SGN confirmation” or “Waiting for fund release” status, please wait for two more hours since there is a rate limit in the initial beta release stage and it may take some time to clear the backlog when the traffic is heavy. If your transfer has been stuck for more than 3 hours, feel free to contact customer support along with your transaction hash on the source chain. These rate limiting will be removed after cBridge transitions out of initial beta release stage.

My transfer shows “Completed” status but I didn’t see it in Metamask. What should I do?

This occurs because the token hasn’t been added to your Metamask wallet on the destination chain. Please click the Metamask icon on the transfer history item and you will be guided to add the token to Metamask.

LP Operations

Is there any risk with providing liquidity in cBridge v2?

Providing liquidity in cBridge v2 is not risk-free. Your liquidity may lose value if there is a significant liquidity imbalance between chains. This is similar to Impermanent Loss in AMMs.
  • Example: Suppose an LP provides 50000 USDT liquidity on Ethereum. A user tries to make a cross-chain transfer of 10000 USDT from BSC to Ethereum. At the time of this transfer, the total USDT liquidity on BSC is significantly lower than that on Ethereum, and thus the bridge for this transfer is 1.001. If the LP’s liquidity is used to bridge this transfer, the LP will receive 10000 USDT on BSC but will send out 10010 USDT on Ethereum to the user. As a result, an impermanent loss of 10 USDT is incurred to the LP. In the long term, the impermanent loss may be recovered as users make transfers of reverse directions.
In most cases, the bridge rate is close to 1 under StableSwap AMM curve and the deviation of pricing is almost always smaller than the fee charged so the impermanent loss only happens when there is an extreme liquidity imbalance between chains.

Why is my liquidity on each chain different from the amount I initially supplied?

Under the LP model of cBridge v2, your liquidity may be moved around different chains as users make cross-chain transfers with your liquidity. For example, you initially provided 10000 USDT to BSC. Later, a user makes a cross-chain transfer of 2000 USDT from Polygon to BSC using your liquidity. Then your liquidity distribution becomes 8000 USDT on BSC and 2000 USDT on Polygon.

How is the LP Fee Earning APY calculated?

The LP Fee Earning APY is estimated as
fee_APY=(1+last_24_hr_feetotal_liquidity)3651fee\_APY=\Big(1+\frac{last\_24\_ hr\_fee}{total\_liquidity}\Big)^{365}-1
The displayed LP Fee Earning APY is the 7-day median.

Liquidity Mining

How should I enroll in liquidity mining?

On the “Liquidity” page, you will see a green “Farming” mark if there is an active liquidity mining session with the corresponding chain and token. Your liquidity for that chain and token will be automatically enrolled in the liquidity mining session and yield farming rewards (no manual staking is required).
Note that your liquidity may be moved around different chains as users make cross-chain transfers with your liquidity. As a result, your enrolled liquidity in each mining session might change as well. Example: Suppose there are two mining sessions, one with BSC+USDT (APY 50%) and the other with Polygon+USDT (APY 30%). Initially, you add 1000 USDT liquidity to BSC in order to reap the 50% APY. Later, your liquidity distribution becomes 600 USDT on BSC and 400 USDT on Polygon due to user cross-chain transfers. In this case, 600 USDT enrolls in the 50%-APY mining session and 400 USDT enrolls in the 30%-APY mining session. It is recommended that LP rebalance the liquidity across different chains to maximize the farming yield.

What is the liquidity mining reward schedule?

See this announcement.

SGN & CELR token

The Celer State Guardian Network (SGN) has been an essential part of Celer Network’s architecture. SGN is a specialized Proof-of-Stake (PoS) chain that serves the purposes of monitoring L1 transactions related to L2 state and faithfully passing layer-2 information back to layer-1 when needed.
In cBridge v2, SGN serves multiple roles: SGN as a share liquidity pool manager that provides PoS-level security and decentralized governance for cBridge v2 SGN as a cBridge node gateway that schedules cBridge node selection and scheduling SGN as a cBridge node Service Level Agreement (SLA) arbitrator that guarantees the Quality of Service of cBridge nodes
For details about SGN and cBridge v2, please refer to the architecture introduction.

Where can I stake CELR token?

CELR holders can stake their tokens into the SGN by becoming a validator or through delegation and actively provide services for Celer Network products (e.g., cBridge v2, Layer2.Finance, Celer State Channel).
CELR stakers in SGN can receive staking rewards and fee rewards from cBridge v2 in exchange for the active block-producing services and crypto-economic security that they provide.
The migration to the new version of State Guardian Network will be released at a later date and currently, users can familiarize the new staking flow at test-sgn.celer.network.

How is the value of cBridge captured?

Unlike many tokens where protocol token holders do not take on active duty of the protocol’s daily function, it is obvious that CELR token stakers and validators are indispensable in the smooth operation of cBridge via the SGN’s new extension.
Specifically, users and LPs in cBridge v2 are required to pay fees to the SGN in return for its services. This is very much like fees being paid for any PoS blockchain validators. These fees are distributed to the CELR stakers in the SGN nodes who generate the block.
There are also a number of system parameters and configurations that require governance-based updates and tuning to ensure the smooth and continuous operation of the system. CELR will also be acting as a governance token for this new component in Celer’s ecosystem.

What is the difference between validator and delegator in SGN?

Validator needs to run a full node in SGN (a Proof-of-Stake chain) while delegator does not. A delgator can stake his CELR token with a validator to earn staking rewards. In return, the validator will take a portion of the delegator’s staking rewards as the commission.

What is the commission rate in SGN?

When a delegator stakes his/her CELR with a validator, a portion of the yielded staking rewards will be taken by the validator as the commission. For example, if the commission rate of a validator is 15% and you have delegated 10000 CELR with this validator. Then 15% of the total staking rewards yielded by your 10000 CELR will be taken by the validator as incentives and your received staking reward will be 85% (as you can see on the SGN web UI).
How is the cBridge fee split between SGN delegator and cBridge LP?
50% goes to SGN delegator, 50% goes to cBridge LP.