https://datatracker.ietf.org/meeting/115/materials/agenda-115-tvr-01

https://datatracker.ietf.org/doc/html/draft-taylor-tvr-prb-stmt-00

1.  Introduction

   Existing Routing Protocols expect to maintain contemporaneous, end-
   to-end connected paths across a network.  Changes to that
   connectivity, such as the loss of an adjacent peer, are considered to
   be exceptional circumstances that must be corrected prior to the
   resumption of data transmission.  Corrections may include attempting
   to re-establish lost adjacencies and recalculating or rediscovering a
   functional topology.

   However, there are a growing number of use-cases where changes to the
   routing topology are an expected part of network operations.  In
   these cases the pre-planned loss and restoration of an adjacency, or
   formation of an alternate adjacency, should be seen as a non-
   disruptive event.