There needs to be clear documentation with an example in the user manual on how to add a second network to an existing filesystem. There are often requests to add a second LNet network (e.g. add TCP network for IB filesystem, or vice versa) and having this clearly described with exact examples would ensure that users can find this information easily.

This should probably go into section 15.3. Multi-Rail Configurations with LNET with a reference from 14. Lustre Maintenance.