What is a withdrawal period?
- Author
- CRYPTO PORT Editorial
- Published
- Updated
- Reading time
- 5 min
In short
A withdrawal period is the time you wait when moving assets from a layer 2 back to layer 1 through the canonical bridge. Optimistic rollups typically set it around seven days to allow for challenges. Third-party bridges can skip the wait, but they introduce a different counterparty risk.
Key points
- The wait when returning assets to L1 via the canonical bridge
- Optimistic designs commonly use about seven days
- The time exists so challenges can be filed
- Third-party bridges shorten it but add other risks
Definition
The waiting time between requesting a withdrawal from a layer 2 through the canonical bridge and actually receiving the funds on layer 1, needed for challenges or proofs to complete.
An optimistic rollup accepts a submitted state as correct and relies on challenges to overturn errors. To leave room for those challenges, the major rollups impose a window of roughly seven days. Allowing withdrawals during that time would let funds leave on the basis of a state that might still be wrong.
Rollups that use validity proofs finalise state only after verifying the proof, so this challenge window does not exist at all. That does not mean zero waiting: in practice it still takes tens of minutes to a few hours for the proof to be generated and posted to layer 1.
If you cannot wait, third-party fast bridges are the alternative. A liquidity provider fronts you the assets on layer 1 and collects the canonical withdrawal later. You pay a fee for the shorter wait, but if that operator or its contract is compromised, the funds are gone.
Watch out for
- · Withdrawals from an optimistic rollup are not instant and typically require about a week
- · After the wait you usually have to claim the funds on layer 1 yourself — nothing arrives automatically
- · Fast bridges trade the wait for exposure to an operator or contract failure