Case 8000 Series Reference Manual page 88

Metric (Information)
This field displays the number of ''hops'' or routers through which an IP
packet must pass before it reaches its final destination (a value of 16 means
unreachable).
TTL (Information)
This field displays the ''time to live'' in seconds for this entry in the routing
table. If this route is not re-advertised before the timeout expires (180
seconds), the destination will become unreachable (indicated by a metric of
16). At this point the TTL will be set to 120, after which time the route will
be removed from the routing table. A TTL of 999 indicates a static route.
i/f (Information)
This field displays the number of the interface over which this route
advertisement was received (0 indicates the LAN).
X870-300351 Issue 1 4-56 Rev.0