when does PMON register to remote listeners

I had a complex problem today: I tried to setup a connection manager, but unlike Arup, I did not like to to use SOURCE_ROUTE. So I had to make the pmon register itself to the cman. As we have already an entry in spfile for remote_listener=REMOTE, I just enhanced this alias in tnsnames.ora by the additional line for the cmans HOST and PORT.
Unfortunately the services did not show up in the cmans show services. Not even an alter system register; did any good, still no service.
After checking with tcpdump (there where really no communication to the cman) and oradebug event 10246 I had still no clue how to find out why my pmon does not like to contact the cman. At a short ask for help on twitter, Martin Nash pointed me to the Note How to Trace Dynamic Registration from PMON ? [ID 787055.1]. There I found the event

alter system set events='immediate trace name listener_registration level 3';

With this, (beside a lot of other useful information) I found the pmon just not knowing about the new entries.
As a solution I had to tell it about the new entries in tnsnames.ora by

alter system set remote_listener=REMOTE;

This made pmon to re-read the tnsnames.ora and accept the new values. All my services shows up in cman now.
Yong Huang has some more Informations about the different trace levels here:

Actually, trc_level 4 (user) is enough to show info about load stats. Other levels are:
0,1: off
2,3: err
4,5: user
6-14:admin
15: dev
16-: support