7

Early soft forks each had their own activation method included in the proposal which relied on flagdays or block version signaling. The latter only allowed a single proposal to be considered concurrently as it relied on incrementing the block version. BIP9 proposed an activation standard which allowed multiple proposals to be considered at the same time. ...


6

Should block height or MTP (median time past [...]) or a mixture of both be used in an activation mechanism like BIP 8 or BIP 9 for defining the timings of the state transitions? What are the advantages and disadvantages of both and how do they compare? The main advantage of MTP is that it usually roughly corresponds to wall time, so it's easy to ...


4

There is only a single concept of Median Time Past (MTP) in Bitcoin, the median time of a block and the 10 blocks preceding it on the same block chain. MTP has always been used in Bitcoin as part of the rules nodes use to determine whether a block has a valid nTime field in its header. Those rules are: The nTime of a block must be greater than the MTP of ...


3

It depends highly on who you ask. Indeed, I (and several others) have argued that there is no reason whatsoever for forced-signaling. Greg Maxwell wrote a long and in-depth piece about why it provides no additional assurances beyond what any soft fork provides on GitHub, which is likely of interest to anyone coming across this post. Ultimately, the point is ...


1

Using block heights for the start and timeout parameters has the advantage of giving miners a known number of signaling periods. Loss of hashpower doesn't reduce the number of retarget periods available for activation. Especially for an activation mechanism over a shorter time horizon (e.g. the Speedy Trial proposal) it may be important to ensure miners ...


1

nickler answered this on IRC. In a mixed network, the rules can become active, but in two separate chains because lot=true nodes will reject blocks from the lot=false chain which doesn't require 100% signaling. The MUST_SIGNAL phase (when lot=true) overlaps with the last two weeks (2016 blocks) of the STARTED phase (when lot=false). In the case that the ...


1

A two week (2016 blocks) forced signaling phase has two major advantages. Firstly, it offers a signal to the network that miners will be enforcing the soft fork rules in the next phase following the forced signaling. It is an imperfect signal as miners could follow the forced signaling and then not enforce the soft fork rules but it is better than nothing. ...


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