This UpToMaxAge value sets the number of seconds between link-state advertisement retransmissions on this virtual link, also used for retransmitting database description and link-state request packets, and should be set well above the expected round-trip time. Setting it too low relative to the actual round trip through the transit area causes unnecessary retransmissions before an ack could arrive. An admin whose virtual link crosses a congested transit area would increase this interval to match observed round-trip delay.