This reports the lifecycle state of this IPsec Security Association: larval while still being negotiated, mature once fully established and passing traffic, dying as it approaches expiration and rekeying, or dead once it's no longer usable. Admins monitor this to distinguish a healthy active tunnel from one that's stuck negotiating or about to expire. Seeing snsVPNState as dying(2) tells the admin this SA is approaching its lifetime limit and should soon be replaced by a rekeyed SA.