Well this appears to be really three questions.
a.) is there (my words, Native) snmp support in Visio, No.
b.) is there SNMP support in VBA, can be and the good news is that it is
fairly easy to implement. The easy way is to use WMI/SNMP. There are good
examples of VBscript that can be altered to support it. I did and it took
about a week of just poking (not serious) at it. I use it on a regular basis
in one of my templates.
c.) Addon. The Fluke tool available in the it tool kit (Visit
www.VisioITKit.com ) is a good example of what can be accomplished. It was
also in the VENT addon which is no longer available.
Al