How will older full nodes cope with 2Mb blocks if they arrive

[Jet Cash]

I'm running 0.11.2 core at the moment, and looking at my peer list, there are 4 running 0.11.2, 1 running 0.10.2, 1 running 0.11.0, 1 running 0.11.1, 1 running 0.9.3
so only half have upgraded to the current version. Will nodes who don't upgrade still be able to process 2Mb blocks, or are the block-doublers trying to force a number of nodes offline?

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[shorena]

I'm running 0.11.2 core at the moment, and looking at my peer list, there are 4 running 0.11.2, 1 running 0.10.2, 1 running 0.11.0, 1 running 0.11.1, 1 running 0.9.3
so only half have upgraded to the current version. Will nodes who don't upgrade still be able to process 2Mb blocks, or are the block-doublers trying to force a number of nodes offline?

From the nodes perspective its just like any invalid block. It will refuse it and not relay it. If the peer continues to send invalid data (e.g. 2MB blocks) it will be banned by the node. Thus the old nodes will over time create a separated network from those that made the hardfork to 2MB. The network will be split, which is expected for a hardfork, the important question is which part will survive and if the other parts death will be quick.

[Jet Cash]

That's what I thought, so how can the 2Mb chain survive if half the nodes (not miners) reject large transactions. It seems that miners won't build large blocks and risk them being rejected. This means that the 2Mb blocks will never be created, hence no practical change to the blockchain.

[Moloch]

That's what I thought, so how can the 2Mb chain survive if half the nodes (not miners) reject large transactions. It seems that miners won't build large blocks and risk them being rejected. This means that the 2Mb blocks will never be created, hence no practical change to the blockchain.

I assume it would be introduced similar to a soft fork...

Allow the miners to vote on it based on block version number... if 75% consensus is achieved, it becomes standard.  Then at 95%, non-standard block are rejected, causing the hard-fork...

If that happens, there wont be much hash power left in the 5% fork (or I suppose 25% when it activates?)... it would die quickly

[shorena]

That's what I thought, so how can the 2Mb chain survive if half the nodes (not miners) reject large transactions. It seems that miners won't build large blocks and risk them being rejected. This means that the 2Mb blocks will never be created, hence no practical change to the blockchain.

I assume it would be introduced similar to a soft fork...

Allow the miners to vote on it based on block version number... if 75% consensus is achieved, it becomes standard.  Then at 95%, non-standard block are rejected, causing the hard-fork...

Thats not "like a softfork" and it does not solve the "full nodes problem" Jet Cash is talking about.

If that happens, there wont be much hash power left in the 5% fork (or I suppose 25% when it activates?)... it would die quickly

The assumption with a hardfork is that nodes will update, preferably all within one day. If they dont - for whatever reason - the network just splits and the new network is smaller. The relay of blocks will work fine within the new network.

[Jet Cash]

OK - so now I've got 2 Bitcoin XT 0.11 in my peer list. How will they handle the 2Mb nominal blocks with under 1Mb in them?

[shorena]

OK - so now I've got 2 Bitcoin XT 0.11 in my peer list. How will they handle the 2Mb nominal blocks with under 1Mb in them?

I have no clue how XT/classic handles blocks, but I would assume the 2 MB limit is just an upper limit as well. Thus they would accept 0.5MB blocks same as core accepts them now.