legacy only nodes do not:
1. receive unconfirmed segwit transactions
2. relay unconfirmed segwit transactions
3. verify unconfirmed segwit transactions
4. verify confirmed segwit transactions in blocks
5. receive true full length blockdata
6. store true full length blockdata
7. relay to other nodes true full length data
if a legacy node sent a stripped legacy block to a segwit node(for syncing purposes). the block would get rejected as its stripped and not got the data segwit nodes need
so legacy nodes are not part of the:
1. full validation
2. full relay
3. full sync
4. full archival
if you did not know this. then please research:
stripped blocks aka filtered block data
downstream nodes aka filtered/bridged nodes
if you think all blockdata is sent and everything gets the same thing. research
--witness
which is a parameter addition to the blockdata RPC call that asks for full data. which legacy nodes do not get to call
the bitcoin devs were very clear about this
legacy only nodes are treated as downstream(separate layer) nodes that receive filtered data
https://bitcoincore.org/en/2016/10/27/segwit-upgrade-guide/#not-upgrading-1In this configuration, you set your current Bitcoin Core node (which we’ll call the “older node”) to connect exclusively to a node running Bitcoin Core 0.13.1 or later (which we’ll call the “newer node”). The newer node is connected to the Bitcoin P2P network as usual. Because the newer node knows about the segwit changes to the consensus rules, it won’t relay invalid blocks or transactions to the older node—but it will relay everything else.
When using this configuration, please note that the older node, if it uses Bitcoin Core defaults, will not see transactions using segwit features until those transactions are included in a block.
If you don’t upgrade, you may experience one difference: if someone who has upgraded to segwit pays you, your wallet may not show you the payment until after it has been included in a block. This is a safety feature that prevents your wallet from seeing transactions it doesn’t completely understand until they’ve been confirmed by a miner.
they even draw pictures for the non-technical minded to understand
legacy only nodes do not fully validate blocks. as the devs have said they rly on segwit nodes to validate fully and then for the segwit nodes to send out data the segwit nodes believe to be true. and so the legacy nodes then simply accept them as true without validating signatures of segwit transactions in blocks. because they are not supplied with signatures that they can understand to verify.
this was explained many many times.
heres one example, explaining it even before segwit was activated that the compatibility was not actually as compatible as proposed.. i even draw pictures..(yea i tried to help ELI-5 it for those that are not technical)
https://bitcointalksearch.org/topic/m.17580661
(p.s before triggering a rage reply. take time to notice the source of the information(the link is from the devs themselves). understand the information. and reply without insult and only with content about the topic. do not meander it into personal attacks at me to avoid learning the truth from the devs themselves)
ooh and do not reply just to reply about this grey paragraph.