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Subject: Re: Questions regarding CA protocol specification and phylosophy
From: Ralph Lange <ralph.lange@gmx.de>
To: Diego Sanz <dshernan80@gmail.com>
Cc: EPICS Tech Talk <tech-talk@aps.anl.gov>
Date: Fri, 15 Sep 2017 13:27:07 +0200
Hi Diego,

On Fri, Sep 15, 2017 at 1:07 PM, Diego Sanz <dshernan80@gmail.com> wrote:
Dear Ralph, Michael, Mark, Kay, Dirk, et al.

FIrst of all thank you again for all recommendations. I am going to try to explain which configuration does work and which doesn't.

I have check the following in two different virtual Machines, One Fedora 26, and the other one CentOS7. In both everything works exactly the same.

config 1. CentOS7 (both EPICS 3.14.12.6 and 3.15.5)
I run 2 IOCs without any specific epicsEnv configuration (as some of you recommended), and I open a new console and I run caget, for reach 2 different PVs from the different IOCs. caget does not find any PV. Then I configure the EPICS_CA_ADDRS_LIST=127.0.0.1  or 10.0.2.15, and it only works for  the last one executed. Right. Now I check with wirshark and netstat, and I can see that both IOCs are sending beacon messages from 10.0.2.15, so I suppose that if I configure EPICS_CA_ADDR_LIST=10.0.2.255 (this is the broadcast address of that private subnet of my computer) it should work, but it doesn't. the messages are:

[dsanz@localhost ~]$ export EPICS_CA_ADDR_LIST="10.0.2.255"
[dsanz@localhost ~]$ caget dsanzHost:ai1
Warning: Duplicate EPICS CA Address list entry "10.0.2.255:5064" discarded
Channel connect timed out: 'dsanzHost:ai1' not found.
[dsanz@localhost ~]$ caget pcounter
Warning: Duplicate EPICS CA Address list entry "10.0.2.255:5064" discarded
Channel connect timed out: 'pcounter' not found.

Then I try with 127.255.255.255 and !IT WORKS!

[dsanz@localhost ~]$ export EPICS_CA_ADDR_LIST="127.255.255.255"
[dsanz@localhost ~]$ caget pcounter
pcounter                       0
[dsanz@localhost ~]$ caget dsanzHost:ai1
dsanzHost:ai1                  6


This looks a lot like you are running a firewall (e.g. iptables) that blocks incoming UDP broadcasts.
Does your wireshark see the name resolution request packages of the client (UDP to port 5064)?
What does 'iptables -L' show?

EPICS_CA_AUTO_ADDRESS_LIST must be "no" or "NO" to shut it off. Any other value is interpreted as yes.

Cheers,
~Ralph


References:
Questions regarding CA protocol specification and phylosophy Diego Sanz
Re: Questions regarding CA protocol specification and phylosophy Kasemir, Kay
Re: Questions regarding CA protocol specification and phylosophy Dirk Zimoch
Re: Questions regarding CA protocol specification and phylosophy Diego Sanz
Re: Questions regarding CA protocol specification and phylosophy Michael Davidsaver
Re: Questions regarding CA protocol specification and phylosophy Diego Sanz
Re: Questions regarding CA protocol specification and phylosophy Ralph Lange
RE: Questions regarding CA protocol specification and phylosophy Mark Rivers
Re: Questions regarding CA protocol specification and phylosophy Ralph Lange
Re: Questions regarding CA protocol specification and phylosophy Ralph Lange
Re: Questions regarding CA protocol specification and phylosophy Diego Sanz

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