Re: EPICS CA and PVA across subnets

[Michael Davidsaver via Tech-talk <tech-talk@aps.anl.gov>]

On 9/29/25 09:29, Johnson, Andrew N. via Tech-talk wrote:
> I believe both CA and PVXS support using multicast for name searches
Correct.  I would encourage more use as I think IP multicast could be a good fit for a network with a complicated topology, but without trust boundaries necessitating a gateway.

> (not sure about pvAccessCPP),
Nope.

> but we don’t have much if any documentation for Base explaining how to configure CA to use that,
Nothing beyond this "test plan" I put together.

https ://wiki-ext.aps.anl.gov/epics/index.php?title=RSRV_Configuration_Test_Plan#Test_.236_IPv4_Multicast_for_search_and_beacons

There is actually not much configuration required.
The core choice is to include a site chosen 224.x.x.x address in the EPICS_*_ADDR_LIST.

> could someone from Fermilab comment on that? I believe Fermi requested and possibly implemented this.
> It would require configuring all the clients and servers, which the previous 2 suggestions don’t.
An item on my long TODO list is to request the assignment of (or simply choose) an IPv4 and/or IPv6 address to use by default.