  In this paper, I develop a generalized method to approximate end-to-end delay
(average delay, jitter and density functions) in packet-switched networks
(PSNs) of any size under 1) Kleinrock's independence assumption (KIA) and 2)
when packet lengths are kept unchanged when they traverse from node to node in
a network, which is an Alternative to Kleinrock's independence assumption
(AKIA). I introduce a new phase-type distribution $C(\mathbf{p},\boldsymbol
\theta)$; and then use results from the network flow theory and queueing theory
to show that the end-to-end delay in PSNs under KIA and AKIA are two different
random variables approximately described by $C(\mathbf{p},\boldsymbol \theta)$.
When PSNs have AKIA, I show from simulation that the method under AKIA
significantly reduces end-to-end delay approximation errors and provides close
approximation compared with the method under KIA.
