BOLT7: extend channel range queries with optional fields

[sstone]

This is a new pull requests that supersedes #519 .

It addresses issues with the original proposal, mainly that it defined a new set of messages, adding complexity to a simple gossip protocol that we knew was limited in the first place.

This proposal does not add new messages, or feature bits, and is fully compatible with existing implementations. Instead of defining new messages it extends existing ones with additional data, that will be ignored by nodes which do not implement extended queries (see BOLT #1).

Nodes that support extended queries will append an additional extended query flag to their query_channel_range queries. If the receiver supports extended queries and understands this flag, it will append the requested additional data to its reply_channel_range message.

There is currently only one type of additional data: one timestamp and one checksum per channel_update.
The checksum is a simple Adler32 checksum computed over the channel_update with timestamp and signature omitted.
Together they can be used to avoid querying channel_updates that are older than the ones you already have, or that are newer but don't include new information.

Nodes can then append additional data to their query_short_channel_ids messages, which consists in one flag per short channel id and specifies what they would like to receive (channel_announcement, or/and one channel_update or both`).

[sstone]

For completeness, there is even a simpler solution: leave query_channel_range as is (no extra flag to signify that you want extended data), and if the receiver supports extended queries they always include extended data in their reply_channel_range.

I chose instead to explicitly signal support for extended queries in query_channel_range, which is more bandwidth efficient (replies won't include extended data unless you ask for it).

[pm47]

@rustyrussell does this correspond to feature option_fec_gossip in #571?
edit: nevermind

[pm47]

For those interested, this feature is now implemented on endurance: 03933884aaf1d6b108397e5efe5c86bcf2d8ca8d2f700eda99db9214fc2712b134@34.250.234.192:9735

[sstone]

There is no need for a specific feature bit for this: additional "extended" data appended to query messages will simply be ignored by nodes which do not implement extended queries (see BOLT 1). It's one of the reasons why this PR is much better than my first proposal: extended queries are completely optional and compatible with current implementations and deployed nodes.

option_fec_gossip refers to new messages to efficiently sync routing tables based on set reconciliation techniques (IBLT, minisketch, ...) that have not been defined yet.

[pm47]

Here are a few test vectors, hope that helps:

{
  "msg" : {
    "type" : "QueryChannelRange",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "firstBlockNum" : 100000,
    "numberOfBlocks" : 1500
  },
  "hex" : "01070f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206000186a0000005dc"
}
{
  "msg" : {
    "type" : "QueryChannelRange",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "firstBlockNum" : 35000,
    "numberOfBlocks" : 100,
    "extendedQueryFlags_opt" : "TIMESTAMPS_AND_CHECKSUMS"
  },
  "hex" : "01070f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206000088b80000006401"
}
{
  "msg" : {
    "type" : "ReplyChannelRange",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "firstBlockNum" : 756230,
    "numberOfBlocks" : 1500,
    "complete" : 1,
    "shortChannelIds" : {
      "encoding" : "UNCOMPRESSED",
      "array" : [ "0x0x142", "0x0x15465", "0x69x42692" ]
    },
    "optionExtendedQueryFlags_opt" : "TIMESTAMPS_AND_CHECKSUMS"
  },
  "hex" : "01080f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206000b8a06000005dc01001900000000000000008e0000000000003c69000000000045a6c401"
}
{
  "msg" : {
    "type" : "ReplyChannelRange",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "firstBlockNum" : 1600,
    "numberOfBlocks" : 110,
    "complete" : 1,
    "shortChannelIds" : {
      "encoding" : "COMPRESSED_ZLIB",
      "array" : [ "0x0x142", "0x0x15465", "0x4x3318" ]
    },
    "optionExtendedQueryFlags_opt" : "TIMESTAMPS_AND_CHECKSUMS"
  },
  "hex" : "01080f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206000006400000006e01001601789c636000833e08659309a65878be010010a9023a01"
}
{
  "msg" : {
    "type" : "ReplyChannelRange",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "firstBlockNum" : 122334,
    "numberOfBlocks" : 1500,
    "complete" : 1,
    "shortChannelIds" : {
      "encoding" : "UNCOMPRESSED",
      "array" : [ "0x0x12355", "0x7x30934", "0x70x57793" ]
    },
    "optionExtendedQueryFlags_opt" : "TIMESTAMPS_AND_CHECKSUMS",
    "extendedInfo_opt" : {
      "array" : [ {
        "timestamp1" : 164545,
        "checksum1" : 1111,
        "timestamp2" : 948165,
        "checksum2" : 2222
      }, {
        "timestamp1" : 489645,
        "checksum1" : 3333,
        "timestamp2" : 4786864,
        "checksum2" : 4444
      }, {
        "timestamp1" : 46456,
        "checksum1" : 5555,
        "timestamp2" : 9788415,
        "checksum2" : 6666
      } ]
    }
  },
  "hex" : "01080f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e22060001ddde000005dc01001900000000000000304300000000000778d6000000000046e1c1010030000282c100000457000e77c5000008ae000778ad00000d0500490ab00000115c0000b578000015b300955bff00001a0a"
}
{
  "msg" : {
    "type" : "ReplyChannelRange",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "firstBlockNum" : 500,
    "numberOfBlocks" : 100,
    "complete" : 1,
    "shortChannelIds" : {
      "encoding" : "COMPRESSED_ZLIB",
      "array" : [ "0x18x54897", "0x74x47820", "0x69x42692" ]
    },
    "optionExtendedQueryFlags_opt" : "TIMESTAMPS_AND_CHECKSUMS",
    "extendedInfo_opt" : {
      "array" : [ {
        "timestamp1" : 164545,
        "checksum1" : 1111,
        "timestamp2" : 948165,
        "checksum2" : 2222
      }, {
        "timestamp1" : 489645,
        "checksum1" : 3333,
        "timestamp2" : 4786864,
        "checksum2" : 4444
      }, {
        "timestamp1" : 46456,
        "checksum1" : 5555,
        "timestamp2" : 9788415,
        "checksum2" : 6666
      } ]
    }
  },
  "hex" : "01080f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206000001f40000006401001a01789c63600002a16b85208ac16bd71930edbaec08002c7804d9010030000282c100000457000e77c5000008ae000778ad00000d0500490ab00000115c0000b578000015b300955bff00001a0a"
}
{
  "msg" : {
    "type" : "QueryShortChannelIds",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "shortChannelIds" : {
      "encoding" : "UNCOMPRESSED",
      "array" : [ "0x0x142", "0x0x15465", "0x69x42692" ]
    }
  },
  "hex" : "01050f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206001900000000000000008e0000000000003c69000000000045a6c4"
}
{
  "msg" : {
    "type" : "QueryShortChannelIds",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "shortChannelIds" : {
      "encoding" : "COMPRESSED_ZLIB",
      "array" : [ "0x0x4564", "0x2x47550", "0x69x42692" ]
    }
  },
  "hex" : "01050f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206001801789c63600001c12b608a69e73e30edbaec0800203b040e"
}
{
  "msg" : {
    "type" : "QueryShortChannelIds",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "shortChannelIds" : {
      "encoding" : "UNCOMPRESSED",
      "array" : [ "0x0x12232", "0x0x15556", "0x69x42692" ]
    },
    "queryFlags_opt" : {
      "encoding" : "COMPRESSED_ZLIB",
      "array" : [ 1, 2, 4 ]
    }
  },
  "hex" : "01050f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e22060019000000000000002fc80000000000003cc4000000000045a6c4000c01789c6364620100000e0008"
}
{
  "msg" : {
    "type" : "QueryShortChannelIds",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "shortChannelIds" : {
      "encoding" : "COMPRESSED_ZLIB",
      "array" : [ "0x0x14200", "0x0x46645", "0x69x42692" ]
    },
    "queryFlags_opt" : {
      "encoding" : "COMPRESSED_ZLIB",
      "array" : [ 1, 2, 4 ]
    }
  },
  "hex" : "01050f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206001801789c63600001f30a30c5b0cd144cb92e3b020017c6034a000c01789c6364620100000e0008"
}

[pm47]

That's how I've implemented it, but yeah it's under specified. Le mer. 20 mars 2019 à 20:59, Rusty Russell <notifications@github.com> a écrit :

…

***@***.**** commented on this pull request. ------------------------------ In 07-routing-gossip.md <#557 (comment)> : > @@ -664,6 +688,22 @@ The receiver of `query_channel_range`: - otherwise: - SHOULD set `complete` to 1. +If the incoming message includes a `option_extended_query_flag` field that it understands, the receiver MAY append an optional `option_extended_info` field to its reply, prefixed with a 2-byte length. The first byte specifies the encoding type, as for `encoded_short_ids`. + +Currently, the only valid `option_extended_query_flag` is 1. The corresponding `option_extended_info` is an array which contains, for each `short_channel_id`, the following values: + + * [`4`:`timestamp_node_id_1`] + * [`4`:`checksum_node_id_1`] What if we haven't received a channel_update in one direction? I assume 0/0 here? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#557 (review)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AB7yvleyvdY1bgpM90qJ1bKghq6udxzKks5vYpMQgaJpZM4aO6Cq> .

[rustyrussell]

OK, so I've implemented this. I've kept the existing logic to send node_announcements for any channel_announcement we send (uniqified). Am testing the vectors now...

[rustyrussell]

OK, I've got a fixup which I applied to your INV gossip PR, which should have gone here instead. Will push. Also, rebased onto v1.0, otherwise I get unrelated regressions...

[rustyrussell]

... and another proposed cleanup (no semantic changes, just integrating the requirements better, I think).

[sstone]

This PR has been discussed in our dev meetings a few times and there are still open points, I'll try and summarise them here. They were raised mostly by @Roasbeef and @cfromknecht , If I've missed anything please add a question/comment which I'll try and address here.

Why do we need this ? We could use heuristics, be more optimistic on the sender's side and work with a "good enough" routing table without trying to get all updates asap. Better heuristics could also be use to broadcast enable/disable updates and reduce "flapping" gossip.

It's very true. But this PR really is a fix for current channel queries which are very good for learning about channels you don't have, but almost unusable for updating the ones you already have. Basically they're just a way of reconciling your list of channel ids with your peer's. Then what ? You've learned nothing about what has changed. If you do nothing, you will get updates as your payments fails with an "update" error, but it's bad UX, especially for mobile nodes when users turn them on, make a single or just a few payments, then turn them off again. And gossip filters (which say “send me everything that is more recent than timestamp X”) don’t really help when you’re offline most of the time since you don’t know what you’re missing to begin with.

I think adding timestamps, and a flag to query specific items and not everything, should not be controversial, especially since now they're completely optional. Do we all agree on that ?

Why do we also need a checksum ? We should use better heuristics to fix the flapping channels issue.

Because then you have the option of ignoring updates that don't change routing policies (or simply flagging them as low priority). Again, better heuristics for broadcasting these updates, as well as stricter peer selection/banning heuristics, would help a lot, but having the option to know that an update does not really change anything * before * you've downloaded it is very useful (and this proposal very cheap from a bandwitdh/cpu point of view).

Should we use TLV for the new optional fields ?

I'm now having second thoughts about this one. Current proposal is simple and consistent, I think that using TLV would just slow things down and would not brings us anything ? But I'll give it a try.

[sstone]

I've updated this PR:

• optional fields now use TLV format
• timestamps and checksums are now independent

These changes heavily borrow on Rusty's tlv branch (mistakes are mine of course :))

Here's an updated test vector:

{
  "msg" : {
    "type" : "QueryChannelRange",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "firstBlockNum" : 100000,
    "numberOfBlocks" : 1500,
    "extensions" : [ ]
  },
  "hex" : "01070f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206000186a0000005dc"
}
{
  "msg" : {
    "type" : "QueryChannelRange",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "firstBlockNum" : 35000,
    "numberOfBlocks" : 100,
    "extensions" : [ "WANT_TIMESTAMPS | WANT_CHECKSUMS" ]
  },
  "hex" : "01070f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206000088b800000064010103"
}
{
  "msg" : {
    "type" : "ReplyChannelRange",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "firstBlockNum" : 756230,
    "numberOfBlocks" : 1500,
    "complete" : 1,
    "shortChannelIds" : {
      "encoding" : "UNCOMPRESSED",
      "array" : [ "0x0x142", "0x0x15465", "0x69x42692" ]
    }
  },
  "hex" : "01080f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206000b8a06000005dc01001900000000000000008e0000000000003c69000000000045a6c4"
}
{
  "msg" : {
    "type" : "ReplyChannelRange",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "firstBlockNum" : 1600,
    "numberOfBlocks" : 110,
    "complete" : 1,
    "shortChannelIds" : {
      "encoding" : "COMPRESSED_ZLIB",
      "array" : [ "0x0x142", "0x0x15465", "0x4x3318" ]
    }
  },
  "hex" : "01080f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206000006400000006e01001601789c636000833e08659309a65878be010010a9023a"
}
{
  "msg" : {
    "type" : "ReplyChannelRange",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "firstBlockNum" : 122334,
    "numberOfBlocks" : 1500,
    "complete" : 1,
    "shortChannelIds" : {
      "encoding" : "UNCOMPRESSED",
      "array" : [ "0x0x12355", "0x7x30934", "0x70x57793" ]
    },
    "timestamps" : {
      "encoding" : "UNCOMPRESSED",
      "timestamps" : [ {
        "timestamp1" : 164545,
        "timestamp2" : 948165
      }, {
        "timestamp1" : 489645,
        "timestamp2" : 4786864
      }, {
        "timestamp1" : 46456,
        "timestamp2" : 9788415
      } ]
    },
    "checksums" : {
      "checksums" : [ {
        "checksum1" : 1111,
        "checksum2" : 2222
      }, {
        "checksum1" : 3333,
        "checksum2" : 4444
      }, {
        "checksum1" : 5555,
        "checksum2" : 6666
      } ]
    }
  },
  "hex" : "01080f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e22060001ddde000005dc01001900000000000000304300000000000778d6000000000046e1c1011900000282c1000e77c5000778ad00490ab00000b57800955bff031800000457000008ae00000d050000115c000015b300001a0a"
}
{
  "msg" : {
    "type" : "ReplyChannelRange",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "firstBlockNum" : 122334,
    "numberOfBlocks" : 1500,
    "complete" : 1,
    "shortChannelIds" : {
      "encoding" : "COMPRESSED_ZLIB",
      "array" : [ "0x0x12355", "0x7x30934", "0x70x57793" ]
    },
    "timestamps" : {
      "encoding" : "COMPRESSED_ZLIB",
      "timestamps" : [ {
        "timestamp1" : 164545,
        "timestamp2" : 948165
      }, {
        "timestamp1" : 489645,
        "timestamp2" : 4786864
      }, {
        "timestamp1" : 46456,
        "timestamp2" : 9788415
      } ]
    },
    "checksums" : {
      "checksums" : [ {
        "checksum1" : 1111,
        "checksum2" : 2222
      }, {
        "checksum1" : 3333,
        "checksum2" : 4444
      }, {
        "checksum1" : 5555,
        "checksum2" : 6666
      } ]
    }
  },
  "hex" : "01080f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e22060001ddde000005dc01001801789c63600001036730c55e710d4cbb3d3c080017c303b1012201789c63606a3ac8c0577e9481bd622d8327d7060686ad150c53a3ff0300554707db031800000457000008ae00000d050000115c000015b300001a0a"
}
{
  "msg" : {
    "type" : "QueryShortChannelIds",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "shortChannelIds" : {
      "encoding" : "UNCOMPRESSED",
      "array" : [ "0x0x142", "0x0x15465", "0x69x42692" ]
    },
    "extensions" : [ ]
  },
  "hex" : "01050f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206001900000000000000008e0000000000003c69000000000045a6c4"
}
{
  "msg" : {
    "type" : "QueryShortChannelIds",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "shortChannelIds" : {
      "encoding" : "COMPRESSED_ZLIB",
      "array" : [ "0x0x4564", "0x2x47550", "0x69x42692" ]
    },
    "extensions" : [ ]
  },
  "hex" : "01050f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206001801789c63600001c12b608a69e73e30edbaec0800203b040e"
}
{
  "msg" : {
    "type" : "QueryShortChannelIds",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "shortChannelIds" : {
      "encoding" : "UNCOMPRESSED",
      "array" : [ "0x0x12232", "0x0x15556", "0x69x42692" ]
    },
    "extensions" : [ {
      "encoding" : "COMPRESSED_ZLIB",
      "array" : [ 1, 2, 4 ]
    } ]
  },
  "hex" : "01050f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e22060019000000000000002fc80000000000003cc4000000000045a6c4010c01789c6364620100000e0008"
}
{
  "msg" : {
    "type" : "QueryShortChannelIds",
    "chainHash" : "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206",
    "shortChannelIds" : {
      "encoding" : "COMPRESSED_ZLIB",
      "array" : [ "0x0x14200", "0x0x46645", "0x69x42692" ]
    },
    "extensions" : [ {
      "encoding" : "COMPRESSED_ZLIB",
      "array" : [ 1, 2, 4 ]
    } ]
  },
  "hex" : "01050f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206001801789c63600001f30a30c5b0cd144cb92e3b020017c6034a010c01789c6364620100000e0008"
}

[cfromknecht]

great work @sstone! really like the direction this is taking and addition of distinct bits for timestamps and checksums. as a whole the proposal looks to be in a good place, i've left some minor comments in line. looking forward to implementing this :)

[t-bast]

ACK 1978561

[sstone]

Since #607 has been approved (yes !), I've implemented a suggestion by @t-bast to use minimally-encoded varints instead of single bytes for query flags. Given the number of options atm they will all still be encoded on a single byte, and test vectors remain valid. I think we're good to go now and hope this will be merged with the TLV PR.

[rustyrussell]

OK, so meeting agreed to remove compression flag and use a straight array for checksums:

http://www.erisian.com.au/meetbot/lightning-dev/2019/lightning-dev.2019-08-05-20.03.html

So I'm going to merge this for c-lightning (only with --enable-experimental-features) for next release: ElementsProject/lightning#2900

I'm not completely opposed to removing the EXPERIMENTAL_FEATURES conditional in the next few days (we tag -rc1 on the 10th of alternate months) if spec is sorted, feature flag is added, and Eclair confirms interoperation in practice. But that's a tight timeline!

[sstone]

@rustyrussell I've changed the formatting and added a JSON test vector. Its format is just a bit different from the one you used but I could get your test to pass with a few changes

[rustyrussell]

OK, I found a bug in my code while implementing the protocol tests; my checksums are wrong.

I assume the crc32 is not supposed to cover the 2 type bytes at the start of the channel_update? ie. our code (now!):

	assert(tal_count(channel_update) > 2 + 64 + 32 + 8 + 4);
	sum = crc32c(0, channel_update + 2 + 64, 32 + 8);
	sum = crc32c(sum, channel_update + 2 + 64 + 32 + 8 + 4,
		     tal_count(channel_update) - (64 + 2 + 32 + 8 + 4));

And for a specific test cases:

1. signature=76df7e70c63cc2b63ef1c062b99c6d934a80ef2fd4dae9e1d86d277f47674af3255a97fa52ade7f129263f591ed784996eba6383135896cc117a438c80293282 chain_hash=06226e46111a0b59caaf126043eb5bbf28c34f3a5e332a1fc7b2b73cf188910f short_channel_id=103x1x0 timestamp=1565587763 message_flags=0 channel_flags=0 cltv_expiry_delta=144 htlc_minimum_msat=0 fee_base_msat=1000 fee_proportional_millionths=10
   010276df7e70c63cc2b63ef1c062b99c6d934a80ef2fd4dae9e1d86d277f47674af3255a97fa52ade7f129263f591ed784996eba6383135896cc117a438c8029328206226e46111a0b59caaf126043eb5bbf28c34f3a5e332a1fc7b2b73cf188910f00006700000100005d50f933000000900000000000000000000003e80000000a
   crc32 = 0x1112fa30

2. signature=06737e9e18d3e4d0ab4066ccaecdcc10e648c5f1c5413f1610747e0d463fa7fa39c1b02ea2fd694275ecfefe4fe9631f24afd182ab75b805e16cd550941f858c chain_hash=06226e46111a0b59caaf126043eb5bbf28c34f3a5e332a1fc7b2b73cf188910f short_channel_id=109x1x0 timestamp=1565587765 message_flags=1 channel_flags=0 cltv_expiry_delta=48 htlc_minimum_msat=0 fee_base_msat=100 fee_proportional_millionths=11 htlc_maximum_msat=100000
   010206737e9e18d3e4d0ab4066ccaecdcc10e648c5f1c5413f1610747e0d463fa7fa39c1b02ea2fd694275ecfefe4fe9631f24afd182ab75b805e16cd550941f858c06226e46111a0b59caaf126043eb5bbf28c34f3a5e332a1fc7b2b73cf188910f00006d00000100005d50f935010000300000000000000000000000640000000b00000000000186a0
   crc32 = f32ce968

[sstone]

@rustyrussell thanks! we do skip the first 2 bytes of the encoded channel_update and find the same checksums, I'll make new test vectors and include your data.

[t-bast]

CL and Eclair have implemented this and correctly inter-operate.
LL said implementation will come later, but concept acked.
@cfromknecht can you tell us if you're ok with the current state of the PR and merging it as-is?

[cfromknecht]

Final version LGTM!! 😀