> I am forking this thread as my reply is not at all related to the JIT-Routing.
Sorry I think my last reply was also getting off subject as well. Thank you for forking the thread > Nonexistent channels (i.e. channels that do not have some backing UTXO in the > Bitcoin blockchain) are not safe to propagate on the network since they are > trivially spammable (i.e. can generate a large number of fake channels to > waste network bandwidth). I hadn't considered the effect this gossip would have on the network. Definitely nodes should not trust one another to tell the truth about nonexistent channels. The source node could blindly allow intermediate nodes to create sub-routes to the next hop. But I wouldn't favor this blind routing idea because fee calculations would be a complete guesses. > A good pruning heuristic is "channel capacity", which can be checked onchain > (the value of the UTXO backing the channel is the channel capacity). > It is good to keep channels with large capacity in the routemap, because such > large channels are more likely to successfully route a payment than smaller > channels. > So it is reasonable to delete channels with low capacity when the routemap > memory is becoming close to full. I'm generally concerned about these heuristics because any time nodes can game a heuristic they will be expected to do so. Gaming a heuristic can be good or bad depending on the side-effects. One side effect of the "channel capacity" heuristic is more reliable payments but another side effect is that low capacity (but possibly reliable) channels are neglected. > It seems to me that s/aggregate-channel/high-capacity-channel/g in your idea > would still work. > In effect, the high-capacity channel is very likely to successfully route in > either direction. > But if by chance it falls into a state where it is unable to route in one > direction or other, the intermediate node has other, lower-capacity channels > that it can use JIT-Routing with to improve the directionality of the > high-capacity channel. > Nothing in the JIT-Routing idea requires that the rebalancing loop is small, > only that a loop exists. > > Nodes still need to track their direct channels (so they are implicitly > always in the routemap). > But payee nodes making BOLT1 invoices could also provide `r` routes in the > invoice, with the given routes being from nodes with high-capacity channels, > so that even if the intermediate channels are pruned due to low capacity, it > is possible to get paid. Without low capacity channels spontaneous payments would not work. Or they would depend on asking for an invoice under the hood. It feels to me that at some point, someone with complete knowledge of the network needs to be employed. Cheers Ariel Lorenzo-Luaces On Mar 28, 2019, 9:51 PM, at 9:51 PM, ZmnSCPxj <zmnsc...@protonmail.com> wrote: >Good morning Ariel, > >I am forking this thread as my reply is not at all related to the >JIT-Routing. > > >Sent with ProtonMail Secure Email. > >> Public nodes could advertise channels which don't actually exist >directly but are instead hidden paths that the source node doesn't need >to know or care about. The fees advertised for these aggregate-channels >would be the aggregate fees expected from the sub-route. > >Nonexistent channels (i.e. channels that do not have some backing UTXO >in the Bitcoin blockchain) are not safe to propagate on the network >since they are trivially spammable (i.e. can generate a large number of >fake channels to waste network bandwidth). > >> I think the biggest gain from this system is that the network can be >more abstract. This abstraction allows all possible subsets of public >nodes to be a clique since all subsets of nodes can be maximally >connected with aggregate-channels as long as the entire network is well >connected. >> This new property of the network could allow a source node to select >a random privacy-clique and rely on payments to be routed along >aggregate-channels without the source node needing to compute or even >know the exact sub-routes. Futhermore, the source node could >exclusively download and listen to the privacy-clique and ignore the >rest of the network structure thus reducing the burden of keeping up to >date network information. > >Let me suggest something else. > >As the LN grows, the public routemap becomes larger and larger, until >keeping them in a fast in-memory data structure becomes infeasible on >cheap hardware. >In all likelihood, at some point in the future, users will want to be >able to limit the memory consumed by implementations for routemaps. > >So, some pruning heuristic is needed, to reduce the resource usage of >large routemaps. > >A good pruning heuristic is "channel capacity", which can be checked >onchain (the value of the UTXO backing the channel is the channel >capacity). >It is good to keep channels with large capacity in the routemap, >because such large channels are more likely to successfully route a >payment than smaller channels. >So it is reasonable to delete channels with low capacity when the >routemap memory is becoming close to full. > >It seems to me that s/aggregate-channel/high-capacity-channel/g in your >idea would still work. >In effect, the high-capacity channel is very likely to successfully >route in either direction. >But if by chance it falls into a state where it is unable to route in >one direction or other, the intermediate node has other, lower-capacity >channels that it can use JIT-Routing with to improve the directionality >of the high-capacity channel. >Nothing in the JIT-Routing idea requires that the rebalancing loop is >small, only that a loop exists. > >Nodes still need to track their direct channels (so they are implicitly >always in the routemap). >But payee nodes making BOLT1 invoices could also provide `r` routes in >the invoice, with the given routes being from nodes with high-capacity >channels, so that even if the intermediate channels are pruned due to >low capacity, it is possible to get paid. > >Regards, >ZmnSCPxj _______________________________________________ Lightning-dev mailing list Lightning-dev@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/lightning-dev
