The Collection Tree Protocol (CTP) is a well-know protocol that provides a 
reliable collection service for wireless sensor networks. In this report, we 
describe our implementation of CTP for the version 3.0 of the Castalia 
wireless sensor networks simulator. Besides being a reference for researchers 
interested in experimenting with CTP in Castalia, this report also provides a 
throughout description of the mechanisms of CTP. As the structure of our 
Castalia-based implementation mimics that of CTP's TinyOS 2.1 components, the 
report also offers several insights into the details of such components. A 
former implementation of CTP for Castalia 1.3, which we had described in 
previous work, is no longer supported. The module implementing CTP for 
Castalia 3.0 is publicly available at http://code.google.com/p/ctp-castalia.