The next-hop IP address used to reach the peer of this Permanent Tunnel. On a link that's meant to stay continuously up, confirming this next hop is the intended path, rather than a fallback route, is part of verifying the always-on tunnel isn't quietly running over a degraded backup path. Example: permanentTunnelNextHop showing a secondary ISP's gateway instead of the primary would mean the always-up link has failed over and is now depending on a path that wasn't the intended primary route.