Recurrence Relation

Apr 2008
A bucket leaks at p packets/sec (pps) over an outgoing link of capacity C when there are packets in the input buffer. Packet arrives in the
input buffer is at a constant rate of c1 for a time interval (0; T], switches to a higher rate c2 for a time interval (T; 2T], switches back to c1 during the interval (2T; 3T], and then again switches to c2 during
the interval (3T; 4T], and so on | where c1 < p < c2 <= C and T >= 1/c2

How can I Obtain a recurrence relation for the delay suffered by a packet arriving at the input buffer?? (the delay is the time elapsed between when a packet p arrives at the input buffer and when p is output from the buffer)

Please let me know urgently! Thanks so much.