Hello,
LDP works together with the IGP you use like OSPF.
The LDP protocol builds LSPs automatically, but it follows the OSPF metrics: the LSP uses the best path(s) available to the LSP destination as OSPF sees them.
Multiple equal cost paths are supported as in OSPF. Load balancing occurs in a MPLS network for IPv4 traffic like in a IP only network.
MPLS traffic engineering using RSVP TE can build manually configured LSPs that do not follow the IGP best path.
Both LDP and RSVP TE can be used in the same environment.
The IGP needs specific configuration to support MPLS TE called traffic engineering extensions.
Only OSPF and IS-IS support these traffic engineering extensions.
Hope to help
Giuseppe