nym/documentation/docs/pages/developers/rust/examples/custom-topology.md

Importing and using a custom network topology

If you want to send traffic through a sub-set of nodes (for instance, ones you control, or a small test setup) when developing, debugging, or performing research, you will need to import these nodes as a custom network topology, instead of grabbing it from the Mainnet Nym-API.

There are two ways to do this:

Custom Topology Provider

If you are also running a Validator and Nym API for your network, you can specify that endpoint. Clients will then use this endpoint to grab a network topology on startup. You can also use this to specify using a testnet.

Import a specific topology manually

If you aren't running a Validator and Nym API, and just want to import a specific sub-set of mix nodes, you can also overwrite the grabbed topology manually.