This is the value, in seconds, used for the suggested ES configuration timer in ISH PDUs when soliciting End System configuration. It is a legacy OSI end-system polling parameter that tells attached End Systems how often to send their ES Hellos back to this Intermediate System, a feature that predates IP-centric IS-IS deployments and is largely irrelevant on modern IP-only networks with no true CLNS end systems. For example, on a legacy OSI/CLNS segment setting this to 60 seconds instructs attached end systems to report in once per minute, but on a pure IP IS-IS deployment this object typically has no observable effect on anything an admin monitors.