Juniper Networks Juniper Networks Juniper Networks Ericsson Cisco Systems This document specifies extensions to the Label Distribution Protocol(LDP) to support the creation of label-switched paths for Maximally Redundant Trees (MRT). A prime use of MRTs is for unicast and multicast IP/LDP Fast-Reroute, which we will refer to as MRT-FRR. The sole protocol extension to LDP is simply the ability to advertise an MRT Capability. This document describes that extension and the associated behavior expected for LSRs and LERs advertising the MRT Capability. MRT-FRR uses LDP multi-topology extensions and requires three different multi-topology IDs to be allocated from the LDP MT-ID space.