Re: [Cs-studio-users] ArchiveEngime configuration with multiple IOC servers

[Kasemir, K. <kas...@or...>]

On Sep 4, 2014, at 9:54 AM, zunbeltz <zun...@es...>
 wrote:
> Thanks for the help Kay,
> 
> Sorry for my ignorance in network setups but I have a question.
> In the EPICS_CA_ADDR_LIST i have the IP addresses of S1 and S2.
> Are addr-broadcast-address-of-subnet1, ... equal to these IPs?

They're different.
On a Linux computer, check /sbin/ifconfig. On Windows, check ipconfig.
Look for the IP address, the net mask, and the broadcast address listed in there.

Your IP addresses might be something like 

S1=123.45.10.1
S2=123.45.20.1

If your net masks are 255.255.255.0, their subnets would be

Subnet where S1 resides=123.45.10.0
Subnet where S2 resides=123.45.20.0

and the associated broadcast addresses would be

Broadcast for S1's subnet=123.45.10.255
Broadcast for S2's subnet=123.45.20.255


Why you would use the IP addresses
  export EPICS_CA_ADDR_LIST="123.45.10.1 123.45.20.1"
respectively
  org.csstudio.platform.libs.epics/addr_list=123.45.10.1 123.45.20.1
?

IP addresses will work through most routers, and you get PVs from just those IOCs, in case you have the same PVs on multiple IOCs.
You should not have the same channel name on multiple IOCs in the first place, so that's not a good reason to list individual IOC IP addresses.

So this might look like the easiest way to get going, but broadcast addresses are better in the long run, i.e.
  export EPICS_CA_ADDR_LIST="123.45.10.255 123.45.20.255"
respectively
  org.csstudio.platform.libs.epics/addr_list=123.45.10.255 123.45.20.255

In the real world, you don't have 2 IOCs. You might have 500, and you can't list the IP address of each single IOC.
Even if you only have 5 IOCs. One day you'll add one more. Do you then want to track down every CA client and update its CA address list?
And if you run more than one IOC on the same computer, you MUST use broadcast addresses, because otherwise you will only see the PVs from the IOC that was started _last_, see again https://wiki-ext.aps.anl.gov/epics/index.php/How_to_Configure_Channel_Access
The only downside: You may need to configure the affected routers to pass those broadcasts.

===> In the real world, your clients will eventually either use broadcast addresses, or the single IP address of a CA gateway (and that gateway then uses broadcast addresses).

-Kay