EVPN Mpls Ping Extension

In an EVPN or any other VPN deployment, there is an urgent need to tailor the reachability checks of the client nodes via off-box tools which can be triggered from a remote Overlay end-point or a centralized controller. There is also a ease of operability needed when the knowledge known is partial or incomplete. This document aims to address the limitation in current standards for doing so and provides solution which can be made standards in future. As an additional requirement, in network border routers, there are liaison/ dummy VRFs created to leak routes from one network/fabric to another. There are scenarios wherein an explicit reachability check for these type of VRFs is not possible with existing mpls-ping mechanisms. This draft intends to address this as well. Few of missing pieces are equally applicable to the native lsp ping as well.