Experimental Physics and
Industrial Control System

Mark Rivers via Tech-talk <tech-talk at aps.anl.gov> · Wed, 17 Mar 2021 12:37:46 +0000

Hi Adam,

> I had a previous post where it was brought up that I should be able to add in the EPICS_CA_ADDR_LIST

> the broadcast address on the IOCs and on the client trying to connect to one of the IOCs on the linux host.

> For example 192.168.1.255 (client broadcast) and 192.168.2.255 (host broadcast), I keep EPICS_CA_AUTO_ADDR=YES.

> But once I change the env variables to have the broadcast IPs, I am not able to caget on the client to any of the IOC PVs running on the linux host.

> Ports are open, no firewall rules.

First, you only need to set EPICS_CA_ADDR_LIST on the client machine to be the broadcast address of the IOC subnet.  You do not need to set EPICS_CA_ADDR_LIST on the IOC machines to be the broadcast address of the client subnet.

I suspect your problem is that you also need to set the router on the IOC subnet to allow "directed broadcasts".  That means it allows broadcast messages to be sent to the IOC subnet from remote machines.

Here is a demonstration that this mechanism works fine.  My client is on the 164.54.160.xxx subnet.  The IOC I want to reach is on the 164.54.162.xxx subnet.

If EPICS_CA_ADDR_LIST does not include 164.54.162.255 then I cannot reach a PV on the 164.54.162.xxx subnet.

corvette:/usr/local/lib>echo $EPICS_CA_ADDR_LIST
164.54.160.255
corvette:/usr/local/lib>caget 15IDA:m1
Channel connect timed out: '15IDA:m1' not found.

However, if I add 164.54.162.255 to EPICS_CA_ADDR_LIST then I can reach that PV.

corvette:/usr/local/lib>setenv EPICS_CA_ADDR_LIST "164.54.160.255 164.54.162.255"
corvette:/usr/local/lib>caget 15IDA:m1
15IDA:m1                       0

The key is that the router on the 164.54.162.xxx subnet allows "directed broadcasts".

Mark

________________________________
From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Manoussakis, Adamandios via Tech-talk <tech-talk at aps.anl.gov>
Sent: Wednesday, March 17, 2021 1:20 AM
To: tech-talk at aps.anl.gov
Subject: Multiple IOCs on one host Issue

Hello All,

I am having trouble solving the use of multiple IOCs running on my linux host.  Currently I start up 4-5 IOCs on my linux host but depending on the order my client cant access one of the IOCs, the host/client are on different subnets 192.168.1.X/192.168.2.X respectively.  I had a previous post where it was brought up that I should be able to add in the EPICS_CA_ADDR_LIST the broadcast address on the IOCs and on the client trying to connect to one of the IOCs on the linux host.  For example 192.168.1.255 (client broadcast) and 192.168.2.255 (host broadcast), I keep EPICS_CA_AUTO_ADDR=YES.  But once I change the env variables to have the broadcast IPs, I am not able to caget on the client to any of the IOC PVs running on the linux host.  Ports are open, no firewall rules.

Thanks,

Adam

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System