[Lightning-dev] Generalizing proportional routing fees to exchange rates

[Rusty Russell]

ZmnSCPxj via Lightning-dev <lightning-dev at lists.linuxfoundation.org> writes:
> Good morning list,
>
> I would like to propose a modification to lightning protocol,
> regarding the use of proportional routing fees.

There needs to be more information across networks than just the
exchange rate.  For example, you need to know the block numbers for CLTV
timeouts on both sides, and you need to know the topology of the
network on both sides.  Those are problems we can push to the edges
of the network, and nobody else should notice.

Moreover, there are two general problems with random currencies on
lightning.  Firstly, it's not clear why you'd want them once bitcoin has
lightning: why use a highway to nowhere (unless you have invested money
in nowhere, of course).  Secondly, we've made several assumptions that
it's not free to create channels, which punts many DoS problems to the
underlying blockchain.  If you can create free channels, this protection
vanishes.

Finally, we're trying to close down spec changes, so we're reluctant to
add features to 1.0 if we can avoid it.

Thanks!
Rusty.