ere E2E backup paths are prepared, in FRR mechanisms local detours are prepared to bypass failed links or NEs. In 6.6 Transport Network order to bypass a failed link one prepares an alternative next hop (NHOP), while bypassing a failed NE requires preparing a next next hop (NNHOP). A related issue for packet switched networks is packet loss. When packet loss is low (say less than one packet in a million) its effects can be ignored except in the most demanding of URLLC applications, but high loss is essentially equivalent to service failure. Best-effort Internet connections may have a PLR of about 1%, while Carrier Ethernet services routinely specify 10-6. While cellular air interfaces have very variable PLR, depending on obstruc- tions, speed, etc., backhaul transport paths tend to have relatively stationary PLR, almost entirely due to buffer overflows in NEs along the path. A new mechanism called Frame Replication and Elimination for Reliability (FRER) for Ethernet and Packet Replication, Elimination, and Ordering Functions (PREOF) for IP/MPLS has recently been proposed to simultaneously achieve ultra-high reliability (better than 5 nines availability) and ultra-low packet loss (IEEE 302.1CB). FRER can best be explained by starting with 1+1 APS. Similar to 1+1, FRER simultaneously sends packets over alternative paths, but it is not limited to two paths (a working path and a backup one), but rather to as many as the planner desires. Unlike 1+1 APS, FRER does not consistently retrieve packets from a working path and only start retrieving from the backup path once a failure has been declared. Instead, it functions on a packet-by-packet basis. It utilizes a per-packet sequence number (adding one if necessary), and selects the first packet with the required sequence number to arrive. This not only automatically combats failures, but compensates for erratic packet loss. However, FRER goes a step further in order to protect against multiple simultaneous failures. Packet replication is performed not only at the head end