[Lightning-dev] Quick analysis of channel_update data

[Fabrice Drouin]

Hello All, and Happy New Year!

To understand why there is a steady stream of channel updates, even
when fee parameters don't seem to actually change, I made hourly
backups of the routing table of one of our nodes, and compared these
routing tables to see what exactly was being modified.

It turns out that:
- there are a lot of disable/enable/disable etc…. updates which are
just sent when a channel is disabled then enabled again (when nodes go
offline for example ?). This can happen
there are also a lot of updates that don’t change anything (just a new
timestamp and signatures but otherwise same info), up to several times
a day for the same channel id

In both cases we end up syncing info that we already have.
I don’t know yet how best to use this when syncing routing tables, but
I thought it was worth sharing anyway. A basic checksum that does not
cover all fields, but only fees and HTLC min/max values could probably
be used to improve routing table sync ?

Cheers,

Fabrice