  Cross-chain interaction is among different blockchains. When the number of
blockchains increases, it is difficult for blockchains to form a single star
topology or a fully connected topology. Meanwhile, different from legacy
networks, the propagation method is required to keep the data validity. Thus,
the blockchain topology and associated propagation methods are two key issues,
which should be ensured during the propagation. In this paper, we first propose
the confirmation-based propagation method to keep the validity of the
cross-chain data. The confirmation method is to seal the cross-chain
transaction synchronized from other blockchains. Second, we point out that a
valid topology requires blockchains to be strongly connected. With this
requirement, we propose several topologies, which match different connection
scenarios. The simulation results show that the proposed methods can securely
propagate the cross-chain data and the connection way is flexible.

Distributed, Parallel, and Cluster Computing