Need some articles on routing sockets in FreeBSD

[Shriek]

I need to understand the usage and to some level details of the routing
sockets (internals may not be the exact word but still ... :-]  ) .... there
is this scenario of this multiple daemons that are communicating using *rt_sock
*and need to trace the communication that is happening ... for this I need
to know rt_sock ... are there any articles on Routing Sockets ... and their
usage / internals ....