Explanation
https://www.oreilly.com/library/view/juniper-mx-series/9781449358143/ch09s03.html The primary drawback to GR is the need for protocol extensions and helper support in neighboring routers, and a stable network topology. If any neighbors do not support GR, or if other changes occur in the network, GR ends up aborting and loss results in the dataplane. Even when all goes to plan and the GR event succeeds, which means there is zero loss in the data plane, there is still control plane flap and a subsequent need for protocol reconvergence between the restarting router and its helpers, ...