Experimental Physics and
That issue exists, correct. [I was calling my rule a "general" rule, which is the wrong term. I meant "basic" rule. I.e., the kind that allows exceptions.]
But even in that case, I would claim that Channel Access technically works. It returns errors that the PV is seen on multiple servers (which is not allowed in CA), because it can see the PV being served from different IP addresses, but it connects to one of the addresses, and that connection will work without further issues.
If a client is written in a way that it reports error messages by printing them (like the command line utilities), it will print error messages. Clients that ignore errors (or hide them in an iconified window, like some display managers) will work.
However, this is definitely not the way to run a CA system. Of course not.
You have to configure the system so that the client sees the PV on only one interface.
There are basically two ways to do that within Channel Access:
Either the server (IOC) binds only to one of the available networks. (Done on recent versions of Base by setting EPICS_CAS_INTF_ADDR_LIST.) No client configuration needed.
Or the client only uses one network to resolve PV names. (By setting EPICS_CA_AUTO_ADDR=NO and EPICS_CA_ADDR_LIST=<broadcast or individual IP addresses>.) No server (IOC) configuration needed.
Outside of CA, there are a zillion different ways to use firewalls and packet filtering/rewriting software to make the client only see the PVs on one interface.
Key point: the name resolution request package (UDP from client to port 5065) must reach the IOC on only one interface. Everything else won't matter much.
Cheers and sorry for the confusion,
On Thu, Sep 14, 2017 at 6:22 PM, Mark Rivers <email@example.com> wrote:
|ANJ, 14 Sep 2017||
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