Lightning Network implementation fragmentation problem has been recognized, and standardized specifications are being designed to achieve interoperability

Development of a major bitcoin scaling solution is fragmented today — but that may soon change.

Lead developers of the Bitcoin Lightning Network met at the Scaling Bitcoin conference in Milan last week to determine how to advance work on the micropayment layer and how to standardize the various ongoing efforts. Representatives from six projects attended the meeting, which participants called the effort the "culmination" of the Lightning Network's work since it was first proposed in 2015.

According to organizers, the idea behind the meetup is to design specifications for various Lightning Network implementations so that the currently fragmented projects (there are currently at least eight different Lightning Network designs) can eventually interoperate.

Prior to the meeting, Lightning Labs co-founder Elizabeth Stark said the group had been conducting technical discussions on the Lightning Network mailing list primarily through twice-weekly phone calls.

Stark told CoinDesk:

“If there is not a proper discussion, there is a risk of incompatibilities and different ideas. We want all Lightning implementations to be discussed and done collaboratively.”

Other participants detailed how information about progress will be shared, with some suggesting an early version of the Lightning Network could be available by the end of the year.

For example, Christian Decker, a core technical engineer at Blockstream, expressed his confidence that the meeting would allow for continued progress towards the goal. He said:

"We successfully finalized all the details needed for interoperability. This concludes the initial exploration phase, and we can now move forward incorporating all the lessons learned."

This much-anticipated top layer of the bitcoin network is designed to increase transaction capacity and speed (hence the name 'Lightning') and do so in a way that adheres to bitcoin's original value proposition (a digital currency that does not require users to rely on intermediaries).

The Lightning Network is widely seen as a way to scale Bitcoin without increasing the blockchain’s throughput, an approach that has been criticized by some proponents of on-chain scaling methods.

Decisions made

As detailed in the blog post, the group made several decisions regarding protocol compatibility (what Lightning Network architect Joseph Poon called ‘critical core protocols’) and ultimately how each Lightning Network implementation should proceed going forward.

Specifically, it involves a 'core commitment protocol' that determines how updates to a micropayment channel between two users are made. (The Lightning Network relies on something called hash time chaining protocols (HTLCs), which ensure that payments on the network cannot be stolen by middlemen).

One of the decisions involves a two-phase HTLC scheme, proposed by Mats Jerratsch, who is working on the Thunder Network implementation at Blockchain.info.

The group also discussed a basic routing protocol specification for how payments ultimately hop across the network, as well as several other implementation details.

These include a format for encrypting communications between nodes and a way to outsource how channels are monitored for fraud so that the responsibility doesn’t fall on users.

Moving Forward

As of now, the group is planning to solicit additional feedback from the Bitcoin community before finalizing the specification and testing compatibility between various Lightning Network implementations in the coming weeks.

“For me personally, the fact that all teams reached similar conclusions and solutions shows that we are on the same track. Now we continue to work on the joint specification and have these Lightning implementations adopt it.”

Additionally, delegates said the update is a sign that work on more advanced bitcoin technology is continuing.

For example, Bitfury Group CEO Valery Vavilov was keen to cite the overall progress made at the Scaling Bitcoin conference, an event that saw multiple technical proposals presented and reviewed, providing a venue for the Lightning Network discussion.

Vavilov told CoinDesk:

“We feel the Milan event is an important step forward for the global adoption of Bitcoin and blockchain for our community and the Lightning Network as a whole.”