What the maximum expenditure on a lighting network channel depends on

Question

I'm new in the lighting network world, and now I have a question on "How it work", so the light network, work with channel and one node for connection to a channel must spend a little of satoshi for "subscribe" to channel, I hope to understand well.

My question is what is the minimum value the satoshi for "subscribe" to the channel?

Also, with the satoshi, I finance the channel and I can spend the maximum value of the loan, right?

An example, if I have a channel X with 10000 satoshi, I can't spend the value with my node > 10000?

Answer 1

so the lightning network, work with channel and one node for connection to a channel must spend a little of satoshi for "subscribe" to channel

In the current implementation, the spending basically involves only one of the node opening a channel by locking some bitcoins in a multi-sig address that is controlled by both parties of the channel. However, while opening the channel the node sending the bitcoins to the multi-sig address may unconditionally send some bitcoins to other parties side of the channel. In the 1.1 implementation we will have the option where both nodes can contribute to the multi-sig.

what is the minimum value the satoshi for "subscribe" to the channel?

There is no specified minimum value but the node needs to maintain a number of conditions to open a channel.

1. You will need to include the amount in funding_satoshis field that can at least cover the transaction fees on-chain to establish the channel.
2. Since commitment transaction is signed before the funding transaction, the to_remote or the to_local outputs of that commitment transaction should be higher than the channel_reserve_satoshi that you specified in the open_channel message.
3. If the other node finds the funding_satoshis to be too less, it MAY fail this channel.

However, there is currently a temporary maximum limit of 2²⁴ satoshi (0.1677 BTC) that can be used to fund a channel.

with the satoshi, I finance the channel and I can spend the maximum value of the loan, right? An example, if I have a channel X with 10000 satoshi, I can't spend the value with my node > 10000?

Although the channel has a capacity of 10,000 satoshi, you can spend only the amount that belongs to your side. Also you cannot spend the maximum amount of the channel balance that you have. Your balance need to be at least equal to the channel_reserve_satoshi which is generally 1% of the channel balance. You can spend the rest that belongs to your side. This reserve is kept so that a node has something to lose if it were to try to broadcast an old, revoked commitment transaction.

Answer 2

You don't subscribe to a channel you open a channel. If you open a channel with 100k Satoshi you can send up to 99k Satoshi (the rest is blocked as the channel reserve). Once you have send some satoshis you can receive them back and resend them. Thus as long as you "earn" your money back you can send as much as you wish.

The lower bound for channels should be 20k satoshis but many people recommend to make larger channels. I suggest to do at least 1million Satoshi per channel. In general a small channel is not very useful.