After the LDP TCP connection session is established, the LSRs negotiate the session parameters, including the method of label distribution to be used. Two methods are available: Downstream Unsolicited: An LSR advertises label mappings to peers without being asked to. Downstream on Demand: An LSR advertises label mappings to a peer only when the peer asks for them. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/mp_ldp/configuration/xe-16-11/mp-ldp-xe-16- 11-book/mp-ldp.html