Ripple formalized its topology requirement in its consensus whitepaper (page 5, section 3.3): https://ripple.com/files/ripple_consensus_whitepaper.pdf https://

Ripple formalized its topology requirement in its consensus whitepaper (page 5, section 3.3): https://ripple.com/files/ripple_consensus_whitepaper.pdf https://ripple.com/files/ripple_consensus_whitepaper.pdf Basically, any two UNLs must have 20% overlap to avoid any risk of a fork.