What happens when a node goes offline for a while?

[1t0ph20]

Let's imaging a full node goes offline for a month, so they're missing ~4300 blocks (just using 10min/blk).

Are there any message exchanges that receive transactions to help sync the 'booting' node with the other peer node's mempools? (I.e. compensate for having a empty tx mempool)?  And if not, why not have a booting node receive a copy for another node's txn mempool (after receiving the missing blocks) so that they can reduce an additional round-trip in compact block relay that relay on generating short_txids from mempool?

[1714798284]

1714798284

[1714798284]

1714798284

[achow101]

A node can use the mempool message to request the txids of all of the transactions in another node's mempools. It can then ask the node for all of those transactions. Bitcoin Core 0.14.0+ will also save the mempool to the disk before it shuts down so it will populate its mempool from the saved data.

[1t0ph20]

Thank you!

To just follow up, if that's the case, why does it still take 3/4 weeks of a node being online before getting 50-60% relayed without additional round trips for missing transactions with compact block relay?

[Jet Cash]

I don't understand the question, sorry guys. I'm often offline for a day or so, and I just start up core, and it re-sync's without any problems. Should I be doing something else other than just starting it up normally?