On 5/5/20 5:31 PM, Olaoluwa Osuntokun via bitcoin-dev wrote: > Hi Antoine, > >> Even with cheaper, more efficient protocols like BIP 157, you may have a >> huge discrepancy between what is asked and what is offered. Assuming 10M >> light clients  each of them consuming ~100MB/month for filters/headers, >> that means you're asking 1PB/month of traffic to the backbone network. If >> you assume 10K public nodes, like today, assuming _all_ of them opt-in to >> signal BIP 157, that's an increase of 100GB/month for each. Which is >> consequent with regards to the estimated cost of 350GB/month for running >> an actual public node > One really dope thing about BIP 157+158, is that the protocol makes serving > light clients now _stateless_, since the full node doesn't need to perform > any unique work for a given client. As a result, the entire protocol could > be served over something like HTTP, taking advantage of all the established > CDNs and anycast serving infrastructure, which can reduce syncing time > (less latency to > fetch data) and also more widely distributed the load of light clients using > the existing web infrastructure. Going further, with HTTP/2's server-push > capabilities, those serving this data can still push out notifications for > new headers, etc.
The statelessness of compact block filters does look useful. Bloom filters for blocks can be inefficient, during a scan with a BIP37 wallet, it's necessary to discard already received merkle blocks as the filter has been updated and the previous results may have missed transactions. Both bitcoinj  and breadwallet-core  handle it using a similar method. The alternative of synchronizing and alternating between requesting blocks and filter updates leads to slow scan times. With compact block filters, a separate wallet process (from the full node) can make adjustments necessary to what it needs to filter without having to communicate with the full node. : https://github.com/bitcoinj/bitcoinj/blob/806afa04419ebdc3c15d5adf065979aa7303e7f6/core/src/main/java/org/bitcoinj/core/Peer.java#L1076-L1079 : https://github.com/breadwallet/breadwallet-core/blob/8eb05454df3e2d5cca248b4e24eeffa420c97e3a/bitcoin/BRPeer.c#L83-L85 _______________________________________________ bitcoin-dev mailing list email@example.com https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev