The Lightning Network FAQ

[NotATether]

Breez released their first Lightning SDK:

Lightning for Everyone in Any App: Lightning as a Service via the Breez SDK

The open-source Breez SDK enables developers to integrate Lightning and bitcoin payments into their apps with zero learning curve or technical expertise. It’s an end-to-end, non-custodial, drop-in solution powered by Greenlight, including a built-in LSP, on-chain interoperability, fiat on-ramps, and other services users and operators need.

With these high level instruments developer can concentrate on their product without having to understand the LN protocol in its finest details.
I guess this and the Strike API release will turbo charge the deveopment of new powerful tools to improve the LN UX!

Is it in closed beta? Because it sure looks like it.

Anyway it looks like something that can be integrated into mobile apps (not sure what the other two categories of SDK are for, but at least one of them says "Design Partner" which tells me is for people who want to improve the SDK) but it's not entirely clear how you'd insert this SDK into a desktop app or a web app.

[cygan]

here is the official tweet of the rtl app (a web-ui for your lnd/c-lightning/eclair node/s) with the announcement of a new update which can be downloaded at the following link: https://github.com/Ride-The-Lightning/c-lightning-REST/releases/tag/v0.10.2


https://twitter.com/RTL_App/status/1635064065105215488

[Carlton Banks]

did the new CLN/c-lightning release come out yet?

[n0nce]

here is the official tweet of the rtl app (a web-ui for your lnd/c-lightning/eclair node/s) with the announcement of a new update which can be downloaded at the following link: https://github.com/Ride-The-Lightning/c-lightning-REST/releases/tag/v0.10.2


https://twitter.com/RTL_App/status/1635064065105215488

Seems like just a c-lightning-REST update (no update to the UI, just the underlying API). I'll update my stuff later today, nonetheless.

did the new CLN/c-lightning release come out yet?

v23.02.2 was released '13 hours ago'.

[darkv0rt3x]

Hi.

I have a couple of questions about some of the terminology used in LN. Namelly in Core Lightning implementation.
When channels are created, there is a small percentage of the channel capacity that is "locked" (is this the correct terminology???) that is called channel reserve, yes? Or is it the dust limit?

I would like someone to clear my mind about these 2 terminologies and give me a light explanation about the 2 of them! What each one is used for, how they are used and when they are useful, etc!

Thanks

[BlackHatCoiner]

[...]

What you describe is called channel reserve. It's the reserve both partners agree to keep as long as the channel will last. It exists to insure disincentive. If you're forced to keep 1% of your channel (for example) you will never publish an older state, even if you only have that one reserve on your side, because you'll lose it. If there was no such reserve, you'd have nothing to discourage you from publishing an older state if you had no receiving capacity, because you'd have nothing to lose.

I have not ever come across with the term "dust limit" on lightning, but I believe it has to do with the prevention of unimportant transactions (e.g, 1 sat). It only exists on-chain as far as I'm concerned.

[darkv0rt3x]

[...]

What you describe is called channel reserve. It's the reserve both partners agree to keep as long as the channel will last. It exists to insure disincentive. If you're forced to keep 1% of your channel (for example) you will never publish an older state, even if you only have that one reserve on your side, because you'll lose it. If there was no such reserve, you'd have nothing to discourage you from publishing an older state if you had no receiving capacity, because you'd have nothing to lose.

I have not ever come across with the term "dust limit" on lightning, but I believe it has to do with the prevention of unimportant transactions (e.g, 1 sat). It only exists on-chain as far as I'm concerned.

Hum, ok. I think I understand the channel reserve.
And I've been reading through Bitcoin mailing list and dust limit seems to be only related to on-chain transactions and to avoid spammy/empty UTXOs into blocks. But if you, in Core Lightning, run lightning-cli listpeers <peer-ID>, there will be a field in the output with the dust limit. This then should be related to the dust limit of the funding TxID that opened the channel?

BTW, the only thing really useful that I found about dust limit was this: https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2021-August/019310.html


Edited;
And following my other post, can we forward payments of a value lower than the channel_reserve? Because I remember when I started with LN, of a problem (not sure if it was opening/closing a channel or forwarding payments) that was related to a bug with the dust limit calculation in Core Lightning!

Edited 1;
The issue was with opening a channel back in 2020. I found the issue that I discovered (I think by accident) back then and fixed by niftynei:
https://github.com/ElementsProject/lightning/issues/4140

[darkv0rt3x]

One other question.

A couple of weeks ago I tried to play a little with htlcmax and htlcmin of my Core Lightning node because I was told that setting lower htlcmax could help nodes keeping more balance over more time in one of the sides of the cahnnel and avoid to rebalance so often. So, I changed some of these values but now I wanted to set them back to the defaults!
Anyone knows what value to set to htlcmax to make it "default"? Would it be the total capacity of the channel or maybe only the outgoing capacity?

[n0nce]

One other question.

Was your first question sufficiently answered / cleared up? Not sure because of your edits.

Anyone knows what value to set to htlcmax to make it "default"? Would it be the total capacity of the channel or maybe only the outgoing capacity?

According to the docs ^[1], by default there is 'no effective limit' except the channel capacity.

So if you want to set it to 'default', simply enter something like 1000BTC (in satoshis); Lightning should just replace that value with your channel capacity and throw that warning. You could also check your channel capacity and set it to that value.

warning_htlcmax_too_high: The requested htlcmax was greater than the channel capacity, so we set it to the channel capacity

[1] https://lightning.readthedocs.io/lightning-setchannel.7.html?highlight=htlcmax

[darkv0rt3x]

One other question.

Was your first question sufficiently answered / cleared up? Not sure because of your edits.

Yes, about distinguishing channel_reserve and dust_limit.

Thanks

Anyone knows what value to set to htlcmax to make it "default"? Would it be the total capacity of the channel or maybe only the outgoing capacity?

According to the docs ^[1], by default there is 'no effective limit' except the channel capacity.

Yes, I was reading there too but the thing is that if it is logical to have htlcmax greater than the lowest value of incoming/outgoing capacity instead of the channel total capacity? Like, let's sat in a "M sats channel, we have it at 50/50. What is the point of htlcmax be 2M sats (total channel capacity) if we can only handle 1M sats payments because the channel is balanced at 50/50?

So if you want to set it to 'default', simply enter something like 1000BTC (in satoshis); Lightning should just replace that value with your channel capacity and throw that warning. You could also check your channel capacity and set it to that value.

warning_htlcmax_too_high: The requested htlcmax was greater than the channel capacity, so we set it to the channel capacity

[1] https://lightning.readthedocs.io/lightning-setchannel.7.html?highlight=htlcmax

Ok, that I didn't know. About the software set it to the channel capacity if the value we set is not suitable!

[darkv0rt3x]

Actually, @n0nce, the max value seems to be the channel capacity - channel reserve.
I just made a test in my Core Lightning and tried to set htlmax to a value bigger than the channel capacity and I got a warning message of not being possible to set that value because it was too big and the value that was set automatically was the one I mentioned -> channel capacity - channel reserve!

[cygan]

a long-awaited feature called route blinding was added to the lightning specification BOLT-4 (Basis of Lightning Technology) yesterday. leading the effort was lighting developer Bastien Teinturier.
its now only a matter of time until first lightning implementations will offer the new routing feature.


https://twitter.com/realtbast/status/1640606307924291585
https://github.com/lightning/bolts/pull/765

[cygan]

how splicing works in the lightning network and what its good for can be seen visually here
further steps/explanations follow...

[darkv0rt3x]

This looks pretty nice but I think it needs to go a bit deeper in the details. I assume it will happen wen you have the other parts ready to share. This is a nice way of putting this so that they can be amost palpable and easily understood. These concepts sometimes get pretty complex to understand with little knowledge at the protocol level.
I would like to see more and also about multi-part payments, for instance. These concepts are still not standard as they need to be implemented by at least 3 implementations, iirc!

[cygan]

This looks pretty nice but I think it needs to go a bit deeper in the details. I assume it will happen wen you have the other parts ready to share.
✂️

as i have already written and indicated, further slides on this complex subject will follow.
these will then hopefully make the splicing topic even more understandable for us.

[hZti]

What I can not understand, even if I will probably be beaten for this question, is why people not try to propose those new features to bitcoin directly? Yes the lightning protocol was not natively adopted, but to split so much developing power away from bitcoin core can only hurt the project in the long run.

[vjudeu]

why people not try to propose those new features to bitcoin directly?

Simple, because if you have on-chain coins, then you can make a single on-chain transaction alone, so there is no coordination needed with another party or anything like that. It is like on those pictures: "Money then could be LESS LIQUID in the Lightning Network than it is on-chain". So, the conclusion is simple: in on-chain payments that problem simply doesn't exist.

If you want to find something similar on-chain, then you can check CoinJoin or cut-through, or any kind of batching. And those things were proposed before, even some of them are actively used, like CoinJoin in JoinMarket, or batching in many services like mixers, exchanges or casinos. When it comes to batching and cut-through, it is not decentralized and non-interactive yet (because we still cannot join transactions in P2P way, like for example MimbleWimble can do), but maybe after next soft-forks we will get there.

[cygan]

here is a interesting list of various projects that have integrated the ldk (lightning dev kit) into their software/code:


https://github.com/peakshift/awesome-ldk/

[ABCbits]

What I can not understand, even if I will probably be beaten for this question, is why people not try to propose those new features to bitcoin directly? Yes the lightning protocol was not natively adopted, but to split so much developing power away from bitcoin core can only hurt the project in the long run.

Mainly because Lightning Network isn't part of Bitcoin protocol. As for splicing feature, it's meant to let user use Bitcoin on mainnet/on-chain without close and re-open channel which create 2 on-chain transaction which takes time and could be costly. And FYI, LN can be used for many cryptocurrency and you can even swap between 2 coins on LN through atomic swaps. Bitcoin Core development heavily focus on full node and wallet functionally, so adding feature (such as LN wallet or CoinJoin) would burden Bitcoin Core development and maintenance.

[Davidvictorson]

What I can not understand, even if I will probably be beaten for this question, is why people not try to propose those new features to bitcoin directly? Yes the lightning protocol was not natively adopted, but to split so much developing power away from bitcoin core can only hurt the project in the long run.

To add to what has been said, integrating the splicing feature or any other new features into bitcoin directly in my opinion would eliminate innovation and experimentation because developers would have to wait for acceptance by the broader Bitcoin community or the Bitcoin Core development team. This in my estimation doesn't foster innovation, competition, and collaboration among different parties and would not allow for greater flexibility, scalability, and efficiency in the overall system.