2. Loop Free Alternate (LFA)

2.1 Solution

The Fast ReRoute Loop Free Alternate (LFA) solution works in pure IP networks, and MPLS networks using LDP [ IETF 5036 ] or Segment Routing [ IETF 8402 ]. This is a purely local solution for the PLR router, requiring no functionality on other routers in the network.

The LFA principle is very simple. The idea is to find a neighboring router to which to send the packet in the event of a nominal path failure, in such a way that this neighbor will not forward the packet directly (using the same interface) or indirectly (via another path). In other words, the aim is to avoid creating a loop, hence the name "Loop...