We analyse a single-server queue in which the server goes through alte
rnating periods of vacation and work. In each work period, the server
attends to the queue for no more than a fixed length of time, T. The s
ystem is a gated one in which the server, during any visit, does not a
ttend to customers which were not in the system before its visit. As s
oon as all the customers within the gate have been served or the time
limit has been reached (whichever occurs first) the server goes on a v
acation. The server does not wait in the queue if the system is empty
at its arrival for a visit. For this system the resulting Markov chain
, of the queue length and some auxiliary variables, is level-dependent
. We use special techniques to carry out the steady state analysis of
the system and show that when the information regarding the number of
customers in the gate is not critical we are able to reduce this probl
em to a level-independent Markov chain problem with large number of bo
undary states. For this modified system we use a hybrid method which c
ombines matrix-geometric method for the level-independent part of the
system with special solution method for the large complex boundary whi
ch is level-dependent.