Published on: 2018-11-20T00:09:16+00:00
The Lightning Network protocol has been updated to allow additional channel_updates in error messages for "upselling" purposes. This means that nodes can now indicate that there are alternate channels available, potentially at a higher fee rate, which could be used instead of the current channel. However, there was some discussion about how useful this feature would be for non-strict forwarding nodes.In an email thread, Rusty Russell announced the decision to allow extra channel_updates in error replies for upselling. But Joost raised a question about the usefulness of this feature for non-strict forwarding nodes, as sending a channel_update in certain cases may not actually be helpful. Joost suggested that instead of using extra channel_updates, the forwarding hint for non-strict forwarding could be communicated as a node property via a global feature bit. This would save time for the sender in trying other channels from that node if they receive a TemporaryChannelFailure.In a message to the Lightning Development mailing list, Joost proposed an idea to improve non-strict forwarding. The idea involves repurposing the `channel_update` message as a 'forwarding hint' in case of failed non-strict forwarding. The intermediate node would iterate over all its channels to the next hop and determine the best channel to use based on a trade-off between minimum fee and time lock delta. The hinted policy of the best channel would then be returned to the sender as a forwarding hint instead of the requested channel. This would provide senders with more certainty about the parameters that lead to successful forwarding and likely reduce payment attempts to complete the payment.However, Joost also noted that senders should not blindly apply the new policy to a route, as an intermediate node may try to maximize its earnings by providing expensive forwarding hints. It is important for senders to be aware that if something changes at the intermediate node, the hint may no longer be valid. Implementing this proposal does not require any onion packet changes, and an intermediate node could advertise that it provides forwarding hints through a global feature bit, although this is optional.Overall, these updates and proposals aim to improve the efficiency and reliability of non-strict forwarding in the Lightning Network protocol, providing senders with more options and certainty when attempting to complete payments.
Updated on: 2023-07-31T20:46:54.196348+00:00