why does the community enable any node to broadcast a transaction or a block, solely to 1 node?
The Bitcoin community is a set of computer systems that talk over the Web utilizing the Web Protocol (IP) and the Transport Management Protocol (TCP). The Bitcoin community protocol is an utility layer protocol that may be a layer above the transport layer (TCP) and Web layer (IP).
As such IP and TCP don’t present a mechanism that stops one laptop from speaking with one particular different. They do not forestall this as a result of that is precisely what they have been designed to do.
IP does embrace each broadcast and multicast capabilities nonetheless Bitcoin makes use of an method usually described as a gossip protocol. Every node communicates on a direct one-to-one foundation with every of a small variety of different nodes. I am not accustomed to managing an IP multicast area however I think it is perhaps troublesome in a purely peer-to-peer association of nodes akin to Bitcoin requires. You even have to permit for nodes which might be offline on the time of the printed.
It’s laborious to think about how one may implement a broadcast-only coverage since new Bitcoin nodes are constantly being created and older Bitcoin nodes disappearing and common Bitcoin nodes are on computer systems which might be solely intermittently related. We would not need the entire community pressured to a halt as a result of somebody with a Bitcoin pockets on their telephone walked into part of a constructing the place telephone reception was poor, or ran their battery down, suffered an influence lower, broke their telephone, and many others. There’ll by no means be a time when all nodes can be found.
I consider this may be particularly troublesome in a peer-to-peer community like Bitcoin, the place there isn’t a centralised management and anybody can write a Bitcoin utility.