I noticed yesterday that Lan Surveyor does not discover sub interfaces on CISCO routers. I wanted a map of an MPLS network and it wouldn't pick up the sub interfaces for any of the links.
LANsurveyor determines connectivity based on a node's assigned IP address(es) rather than network interfaces. Unless the sub-interfaces have an assigned IP address, then LANsurveyor will not represent a connection to a switch or to a subnet.
The subinterfaces have IP addresses. The MPLS network consists of 7 sites. If I give surveyor the IP of one of the routers and give it even 10 hops it will not search for IP nodes on the sub-interface network segment, find the other side, and keep discovering nodes. At the same time it fully searches for IP nodes on segments associated with a physical interface.
LANsurveyor doesn't have explicit handling of MPLS or BGP. When determining directly connected subnets for a given node (e.g. a router), it uses SNMP MIB-2 addresses and follows those for each additional hop. If you would like to pursue this issue further, please open a support ticket and provide the LANsurveyor log file (Start>SolarWinds LANsurveyor>LANsurveyor Log.txt).