[c-lightning] Routing: bias against smaller channels

[michael at schmoock.net]

Hey, update:

In code this looks like this:

https://github.com/lightningd/plugins/pull/246/commits/2dbff662f712c7883169e7557f5170e356c942e8

Whats your thoughs?
Michael


On 2021-05-31 10:47, michael at schmoock.net wrote:
> Hi,
> 
> I'm currently thinking about the same issue while I'm polishing the
> rebalance plugin.
> My current thoughts on that: This should probably not be done by
> changing the getroute
> code but by the one that is using getroute in a way like for example:
> 
> - Start trying shorter routes first via "maxhops" parameter.
> - In the first iteration use a lot higher "msatoshi" value than
> needed, for example by a factor of 4 times bigger.
> - When you get "route not found errors" decrease the msatoshi factor
> and retry getroute.
> - When you reached a msatoshi factor of 1 (neutral) and still run into
> "route not found": increase the maxhops paramter by 1 and reset the
> msatoshi factor to 4 again for the next interation.
> - Repeat the loop until maxhop reached i.e. 10
> 
> Something like this. I'm still fiddling with the details.
> Just my two Satoshi...
> 
> Michael
> 
> 
> On 2021-05-27 23:55, nibnalin wrote:
>> Hi all,
>> 
>> I've been reading through the c-lightning codebase over the past
>> couple weeks (great comments and explanations throughout the codebase,
>> by the way!) and ran into this FIXME:
>> https://github.com/ElementsProject/lightning/blob/master/gossipd/routing.c#L710
>> 
>> I was wondering if there is any past discussion of how a solution
>> could work, or what possible ways to work with it might be. In
>> general, I'm curious how routing biases or other changes such as this
>> one are evaluated for their utility. I implemented a pretty simple
>> bias as a possible draft here:
>> https://github.com/nalinbhardwaj/lightning/commit/2ef2f7822a874dbe42e311e8787a28d5860452b4.
>> Curious if anyone has any thoughts on it. :) I'm not sure how I can
>> fine-tune it to be useful in real settings.
>> 
>> Besides this particular task, curious if anyone has any suggestions
>> for other changes to work on to get a better understanding of
>> lightning network.
>> 
>> Thanks!