Experimental Physics and
Industrial Control System

"Jeff Hill" <[email protected]> · Mon, 27 Sep 2010 16:00:23 -0600

> Do you have to configure CA clients running on a 
> machine with multiple interfaces to only use one 
> of them for broadcasts, or would CA take care of 
> that for you if they're all in the same subnet?

The default is for CA to broadcast on all active
LAN interfaces it finds, and unicast on all 
active point-to-point interfaces it finds.

I suppose that a new environment variable perhaps
named EPICS_CA_SUBNET_LIST might make configuring
broadcasts for all interfaces attached to one or 
more subnets easier. 

Nevertheless, multicasting will probably be easier 
to configure, and more importantly for your users 
to understand, if one doesnât object to enabling 
multicasting in his control system routers. Many 
sites already make this concession for at least some 
of their Allen Bradley PLCs, as I recall.

Jeff
______________________________________________________
Jeffrey O. Hill           Email        [email protected]
LANL MS H820              Voice        505 665 1831
Los Alamos NM 87545 USA   FAX          505 665 5107

Message content: TSPA

> -----Original Message-----
> From: [email protected] [mailto:tech-talk-
> [email protected]] On Behalf Of Andrew Johnson
> Sent: Friday, September 24, 2010 11:10 AM
> To: [email protected]
> Subject: Re: Soft IOCs and Port Numbers
> 
> On Friday 24 September 2010 11:24:42 Ralph Lange wrote:
> >   On 24.09.2010 12:16, Eric Norum wrote:
> > > Or run every IOC in it's own virtual machine?
> >
> > Have been investigating that- too thick. Running a VM only to have an
> > additional IP address .... nah.
> >
> > I would prefer the solution that uses virtual network interfaces on
> the
> > soft IOC host. Relatively slim, completely transparent, does not need
> > additional services.
> 
> But it does require configuring a alias interface and providing an IP
> address
> for each soft IOC you want to run.  If you're using non-routable
> addresses the
> extra IPs may not be a major issue (as long as your subnets were made
> large
> enough), but it might mean getting IT involved every time Controls
> wants to
> add a new soft IOC.  Do you have to configure CA clients running on a
> machine
> with multiple interfaces to only use one of them for broadcasts, or
> would CA
> take care of that for you if they're all in the same subnet?
> 
> A machine-specific name-server would be more efficient since each PV
> name
> request only has to be checked once by the name-server rather than by
> all of
> the IOCs on the machine.
> 
> - Andrew
> --
> The best FOSS code is written to be read by other humans -- Harald
> Welte

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System