LDP is enabled on an interface by configuring the interface command mpls ip. On an LSR, LDP is usually enabled on all the interfaces on which the IGP is enabled. Much easier than configuring mpls ip on every interface separately is enabling LDP Autoconfiguration for the IGP. Every interface on which the IGP is running then has LDP enabled. The OSPF router command to enable LDP Autoconfiguration is this:
mpls ldp autoconfig [area area-id]
As you can see, it can be enabled for just a specific OSPF area. You can also disable it from specific interfaces if you want to. The interface command to disable LDP Autoconfiguration on an interface is as follows:
no mpls ldp igp autoconfig
Look at Example 4-23. “Interface config” ...