Hi all, first time posting. I’ve tried googling a bit but its not totally clear to me. Say I have servers A, B, C, and D.
Can servers A and B federate, and then separately C and D federate?
If so, can A B and C be federated, but separately C and D be federated, so D is not recognized as federated for A?
If A, B, C, and D are federated, and it becomes apparent that D is a bad actor, how does D become defederated?
I feel like these kinds of situations are critical to ensure long term success. I really appreciate any answers anyone can provide!
Hey, great question! It can feel a little bit weird at first to try and grasp, but it’s actually pretty simple.
Let’s say that we have four servers: sunshine.city, doom.club, goblin.camp, and clown.town.
Sunshine City, Clown Town, Goblin Camp, and Doom Club all federate together. Sunshine, Goblin, and Doom all get memes from Clown Town. Goblin and Doom have a lot of users that primarily focus on gaming. Sunshine gets memes from Clown Town, but doesn’t really talk to the other two instances.
So the question is: do they federate stuff between all instances, or not? The answer hinges on two points:
When people on SunShine City follow a meme community on Clown Town, they’re going to see memes from that community. But, that community can also have posts and users from Goblin Camp and Doom Club. So by extension, SunShine City will get content from those other places, even if the only point of contact is through that community. Granted, they will not be exposed to everything that gets posted to those other servers, a SunShine City is only a recipient for activities when it comes to posts in that community.
The waters can definitely get muddied further, though, depending on whether users from these different instances end up subscribing to one another or interacting with more communities that overlap these spaces. I’m not 100% sure how Lemmy approaches federation, given that it doesn’t exactly rely on timelines in the way that Mastodon does, but Mastodon users will generally get content from the people they follow, as well as the people those people follow as well, filling up a separate “Federated” timeline.
With regards to defederation, that ends up being an executive decision by an instance admin. Let’s say that Goblin Camp ends up being a super toxic community, and SunShine City wants nothing to do with them. Blocking any inbound activities from goblin.camp will cause the receiving instance to simply drop the messages - meaning, federated messages in overlapping communities like !memes@clown.world would reflect that to sunshine.city locally. They’d get all the other posts, comments, and messages, but anything from goblin.camp shouldn’t come through.