126 sats \ 2 replies \ @RocketNode 24 Aug \ on: Why happen force closures on LN channels? bitcoin
The question I see often is why FC?
The actual balances for each side of the channel can only be settled on chain. So when one side sees something they don’t like, they can broadcast the latest commitment tx provided from the other side. According to Matt, fee mismatches “could” be an attack and thus decide to go on chain to be safe. This is why most of the FCs from the recent fee spike were initiated by LDK nodes.
I highly suggest reading Elle’s write up on lightning channel operations. It’s very long and detailed. https://ellemouton.com/posts/normal-operation-pre-taproot/
very good article thanks for mention it!
Still do not say too much about how to avoid these FC.
Why the anchor reserves are not used as buffer for these high fees spikes?
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Reserve is to make sure the opener has enough balance on their side to allow for the commitment fee to grow. You have to account for the tx size of all outputs which can constantly change, anchor + balances + inflight htlcs, x fee rate.
FCs happen when one party deems their balance as not safe. Usually this means a htlc has not been settled and expired. This could allow anyone with the preimage to steal it. However, each lightning implementation has criterias for going on chain. The massive fee change could be seen as an attack because if the commitment fee is too low, the mempool could be full where the commitment tx fee would be below the min relay fee rate. This could prevent the FC making it to the miners so neither side would be able to CPFP.
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