This reports the Layer 2 link type, such as Ethernet, PPP, or ATM, of the adjacency forwarding element within this list, defaulting to unknown if the list does not contain an adjacency forwarding element at all. This is a quick way to confirm what kind of physical/logical link a given prefix's traffic actually egresses on, which matters when the same forwarding-element list might otherwise obscure whether traffic goes out, say, a PPP link versus an Ethernet one after label operations. A prefix forwarded over a point-to-point WAN circuit would show this object as PPP or similarly serial-appropriate, letting an admin confirm the egress link type without separately checking the physical interface configuration.