This document describes two routing simulators for computer communication networks. One is to simulate the new Arpanet routing algorithm [MCQ 80] and its extension to hierarchical networks [TSA 82, RAM 83], and the other one for the original Arpanet routing algorithm [MCQ 74] and its extension to hierarchical networks [MCQ 74, KAM 76, HER 82]. The novel features of the simulators are that they are highly parametrized so that they could be used for a variety of purposes. Specifically, the input network could be of arbitrary clustering structures, the reliability of links of networks could be arbitrarily chosen, the delay along each link could be arbitrarily predetermined according to the real network environments, and the patterns and flow rates of input data streams could be arbitrarily chosen. This report is intended to be used as a manual for using the simulators, thus many details of the algorithms will not be presented for the sake of brevity. The detailed algorithms could be found in [MCQ 7, MCQ 80, RAM 83].