Chain Network is the summary of chains, cells (shards), tokens, its ledgers and whitelists (GDB) providing with nodes over the internet or an intranet. Network could be public, where everybody could connect with it. And private] where only authorized users could connect with.
All the assets are common for network. Tokens are declared for all the network, its impossible to have token only for specified chain or cell (shard). Because of this, ledger is also single for network and could be spread over the different parts.
Every network has its core that seeds its for newbies. It could be merged with root nodes, archive nodes or be temprorary duties for general node. When the new node connects to seed node its get the cells list and node lists, then find the nearest one (or few) and bring up links to them. After that the uplinks update the lists] and add the newbie in it.
Network brokes down by shards - groups of nodes that has common data, chains and connected with themeselfs. More details about cells here.