Functionality of introducers

I am aware that similar questions have been asked before, but I am still not clear with the working of syncthing and functionality of introducer.

I have a master node A, sharing folder X with nodes B, C and E (cluster 1) and folder Y with D, E and F (cluster 2). Q1. If on nodes B, C and E, folder X’s configuration only has node A’s device details, then the syncing from A to B will not involve the other nodes of the cluster i.e., there will be no exchange between B, C and E (essentially defeating the purpose of using a p2p protocol)?

Q2. If there is no exchange between B,C and E in the above question, will marking A as introducer solve the problem?

Q3. If A is indeed marked as an introducer for both clusters, will nodes B, C and E be able to see D, E and F? Please note the two sets of nodes share different folders.

Sorry, if I’m question seems redundant or too specific!

A1: Yes.

A2: If you set A as introducer on B,C & E, it will tell them about each other, they will add each other and from then on sync with each other as full p2p mesh.

A3: Introducers should only tell the nodes about other nodes sharing the same folders, so the clusters will remain separate and only A knows all folders and devices.

In my opinion, introducer should only be used, if you add devices often or have a big cluster. The introducer will only save time for adding devices as you could easily add them manually. Also, currently, if A is set as introducer on C and you want to remove E from C, it won’t work, as the device will get re-added automatically by A.

Thanks a ton! The cluster that I’m working on will mostly have many nodes, added frequently, so this saves a lot of time :slight_smile: