MPLS advertising multiple customer subnets
When employing MPLS, most examples shown within labs show how to advertise a single customer subnet to the MPLS infrastructure to allow communication with that particular subnet. This is typically done using some routing protocol such as EIGRP or OSPF or even BGP between the CE and the PE routers. For example, in the following topology, only the 1.1.1.1/32 and 5.5.5.5/32 customer subnets are advertised into MPLS.
Typically, a customer will have more than a single subnet behind their CE. There will typically be more network infrastructure behind the CE with multiple routers and VLANs. In order to ensure that those subnet are made available via the MPLS infrastructure, those networks must also be shared, via the appropriate routing protocols or static routing with the CE routers, so they can be further redistributed into the MPLS infrastructure.
Links
https://networklessons.com/mpls/introduction-to-mpls#MPLS_Configuration