Yesterday, LND released lnd v0.10-beta. Aside from many small improvements, there are two notable features. Sending up to 0.167 BTC via multiple paths (multipart payments) is now possible. Eclair also has a full MPP support while c-lightning supports only receiving so as long as most nodes are up-to-date, the payments should go through without any problems. The other feature worth mentioning is support for Partially-Signed Bitcoin Transaction (PSBT). It is now possible to fund multiple channels using a single transaction directly from one's wallet if it supports PSBT.

The splitting algorithm that is employed is a variation of "divide and conquer". First, lnd will try to complete the payment in a single shot. If that is not possible - because channel capacities aren't sufficient or other constraints like the fee limit are hit - an attempt is made for half the payment amount. After that htlc has been launched, a second path is searched for to pay the remaining amount (the other half). If further failures happen, amounts are repeatedly split until a minimum amount limit is reached or the payment succeeds.

We opted for this relatively simple strategy to begin with. It is expected to address various basic liquidity problems that arose in the past, but it is unlikely to always execute payments in a way that is optimal. The field of multi-path planning is still mostly uncharted and contains lots of challenges. Therefore we hope to collect valuable feedback with this release and use that to drive further development.