Bitcoin scaling timeline explained

As you might be aware Bitcoin is trying to achieve scaling through implementation of segregated witness, but there are two competing parties at play proposing to achieve this via uasf or segwit2x.

To understand this timeline we must first define following glossary of terms:

Segregated witness: also known as segwit is a proposal to remove data related to signature from transaction in order to decrease their size, hence allowing more transactions to be placed in one block. To understand this topic further, I encourage you to watch Peter Rizun’s presentation from The future of Bitcoin 2017 conference.

BIP148: Is one of two proposals put forward by Bitcoin’s core developers, It relates to user activated soft fork (uasf) approach where users i.e. wallets, exchanges etc… can activate it by signalling readiness. This doesn’t require acceptance from miners, creates a new chain with idea of it overtaking current one and making everyone transition.

SegWit2x: Is second proposal put forward by bitcoin mining giant from china Bitmain. It is essentially similar to BIP148, but gives more freedom to miners by making old nodes compatible with new ones therefore supporting legacy chain in a way.

July 14, 2017 — Deployment for BTC1

New York Agreement is a fork of the Bitcoin Core codebase called “BTC1”, this is a beta software released on June 30th. July 14th is the day when everyone who agreed on this should install BTC1 beta software and start testing.

July 21, 2017 — Start of BIP91 signalling

SegWit2x team has set this deadline for all BTC1 miner nodes to be ready and start signaling. Miners can help activate SegWit by mining something called “bit 4” blocks using BTC1 software.

July 23, 2017 — BIP91 Lock in

This is earliest set date for BIP91 to have 269 blocks of previously pre-defined 336 blocks (about 80%) signalling readiness. If this is achieved miners will have another couple of days to comply with BIP91 soft fork, otherwise there is a risk of mining invalid blocks.

July 25, 2017 — BIP91 Activation

After another 336 blocks since BIP91 lock in, BIP91 has potential to go into effect, blocks that are not signalling readiness for SegWit2x / BIP141 will be declined. Miners should now only mine top of blocks signalling SegWit2x / BIP141.

July 29, 2017 — BIP91 Deadline

If split in chain is to be avoided and to ensure that BIP91 is compatible with BIP148, this day is the deadline, if BIP91 has not yet activated there is high chance that Bitcoin chain is about to split. If this happens regular users should educate them selves about potential risks and how to store 2 versions of Bitcoin. As a miner you will have about 2 days to decide which chain you want to mine on.

July 31, 2017 — BIP141 Deadline

This is, technically, second deadline to avoid chain split. For this to happen, either BIP91 must be active or BIP141 must lock in.

August 1, 2017 — BIP148 Activation

This is the day UASF BIP148 activates. At around 00:00 UTC BIP148 nodes will start rejecting blocks that are not signalling readiness fro segregated witness. If either BIP141 or BIP91 have locked in or activated, chain split will be avoided. If not, there is one last chance to avoid splitting by supporting BIP148 via majority of hash power. If none (BIP148, BIP91, BIP141) have attracted majority, chain will split creating “Old Bitcoin” and “New Bitcoin”.

August 4, 2017 — Possible Bitcoin ABC Launch

Bitmain (major Chinese bitcoin mining company) announced that if BIP91 does not activate before August 1 and BIP148 looks like it did, they will fall to contingency plan and launch new Bitcoin ABC. Such coin will share common history with Bitcoin up until August 1st, but will continue to be mined privately by Bitmain for the first couple of days after that. It’s difference from Bitcoin is in few protocol rule changes and increased block size limit. Miners will be able to download additional software and start mining Bitcoin ABC if they desire.

August 4, 2017 — Possible Proof-of-Work change for BIP148

This is user side response to SegWit not locking in via BIP148. If this happens, users will start to reject blocks not signalling readiness, therefore incentivising miners to follow BIP148 chain. This can be created via yet another new “NewPowBitcoin”.

Mid-Late August, 2017 — SegWit Lock in

If everything goes according to plan and chain split is avoided, segregated witness upgrade should lock in some time during mid, possibly late August. If chain splits by this time however, situation will become drastically more complex as there can potentially be 4 different Bitcoins: “Legacy Bitcoin”, “148 Bitcoin”, “NewPoW Bitcoin”, “Bitcoin ABC”.

Late August, Mid September, 2017 — SegWit Activation

If chain split drama is avoided, SegWit should Activate around this time. Assuming you are running compatible client, you can now benefit from new features.

Late October, Mid November, 2017 — SegWit2x Hard Fork

If SegWit was achieved via BTC1 / SegWit2x a hard fork is set to take place around this time enforcing mining of blocks with base size bigger than 1mb, therefore making other clients incompatible with it unless upgraded to new fork.
If situation gets to this it is almost certain that not everyone will upgrade to this, due to nature and risks of hard fork, community has largly rejected the proposal, as it seems like Bitmain’s desperate attempt to make their vision happen.

~SC

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