Two mutually trustworthy nodes have the option of opening a transaction channel to perform high-frequency offline micro-transactions. This can be done between two relatives/friends that already have frequent social interactions - think chatting, transferring money, sending photos, etc. through encrypted apps on the platform. These are defined as “Friends or Relatives Nodes” (FRN) and are given the aforementioned privilege.
Two high reputation nodes that don’t have any prior interactions also have the option to open a transaction channel. Based on their high reputation, it’s a given they already have prosocial behavior within their own circles, and are therefore given this privilege. For micro-transactions, the cost of reputation loss is greater than the possible benefits earned by malicious nodes.
Usually, 2 nodes without prior interactions cannot open payment channels. But for High-Reputation-Nodes, payment channel can be opened even without prior interactions. For High-Reputation-Nodes, since they have a good reputation performance in their own social networks. For small micro- transactions, being a malicious node is economically unfeasible, since the cost of reputation loss is far greater than the possible benefits.