3. Remote Loop Free Alternate (RLFA)

3.1 Solution

The Fast ReRoute "Remote Loop Free Alternate" (Remote LFA) solution is an extension of LFA. RLFA is specified in RFC 7490 [ IETF 7490 ]. RLFA is similar to LFA, except that the backup next-hop is not necessarily directly connected to the PLR by a physical link, but can be remote and joined by a virtual, tunnel-type link. In this case, RLFA uses an IP or MPLS tunnel to send its packets directly to this RLFA node.

Figure 8 illustrates a ring topology for which LFA cannot find a solution. RLFA finds a solution when the metrics of the links in the ring are close enough. Router "S" uses a tunnel (in blue)...