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Hi,

when requesting a new group by feature for compass [1] (#6662 [2]) I discussed with Karsten about how to handle asynchronous/overlapping families:

karsten:

Here's an example. Assume we have three relays: A, B, and C. These relays state the following family relationships:

A: A, B B: A, B, C C: B, C

We require mutual agreement about being in the same family, so we could either come up with family A, B or with family B, C. Which one is correct?

I proposed to go with family = A, B, C because there is a mutual agreement between A<->B and B<->C.

A and C agreed to be in a family with B, and B agreed to be in a family with A and C. Such configurations can be found in the wild mostly due to incomplete MyFamily configurations on relays in big families.

As every big relay operator knows configuring families is a non-trivial effort with a growing number of relays. Now I thought about it and wanted to suggest this MyFamily interpretation as an alternate approach to the fully mutual setup where *every* relay must be reconfigured as opposed to just two of them. Why? This would reduce the configuration effort required when adding a new relay to *two* relays regardless of how many relays are in your family.

Now, the MyFamily configuration overhead for big families is a well known problem so I suppose someone else did already propose this approach?

What do you think about it?

[1] https://compass.torproject.org [2] https://trac.torproject.org/projects/tor/ticket/6662

a additional example to make this clearer:

A: A, B, C B: A, B, C C: A, B, C D: A, B, C, D

family = A, B, C

A family member must have a *mutual* agreement with at least *one* node.