EPICS Controls Argonne National Laboratory

Experimental Physics and
Industrial Control System

1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  <20172018  2019  2020  2021  2022  2023  2024  Index 1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  <20172018  2019  2020  2021  2022  2023  2024 
<== Date ==> <== Thread ==>

Subject: Re: Why do I need to prevent looping when deploying CA gateway
From: Andrew Johnson <[email protected]>
To: <[email protected]>
Date: Mon, 24 Jul 2017 16:50:30 -0500
Hi Lin,

On 07/24/2017 10:43 AM, Wang, Lin wrote:
> When I was deploying CA gateways for our facility recently according
> the users guide [1], I was confused about the motivation for
> preventing looping mentioned in the document. Does CA gateway looping
> affect anything? Will CA gateways work improperly when looping
> happens?
> 
> For example, when I create two CA gateways (gateway1 and gateway2) in
> one PC with eth0 and eth1 connecting to NetA and NetB respectively.
> Gateway1 binds eth0 as CA server IP and adds eth1/NetB to
> EPICS_CA_ADDR_LIST, whereas gateway2 binds eth1 as CA server IP and
> adds eth0/NetA to EPICS_CA_ADDR_LIST. This way, there is a loop and
> the internal PVs inside both gateway1 and gateway2 can be accessed
> from both NetA and NetB. However, I cannot see anything abnormal, the
> two CA gateways still work properly. Even if I capture UDP/TCP
> packets using Wireshark with cashark plugin, I still cannot see
> excessive packets.
> 
> Any hints or answers are appreciated. Thanks.

I haven't experienced this myself, but try stopping, turning off or
disconnecting one of the IOCs while monitoring the network traffic. I
suspect that's when looping might start to have an effect. Make sure you
have active client connections (MEDM/EDM/CSS-BOY) both going through the
gateway(s) and local to that IOC while you do that.

If you're using the -signore option or setting the environment variable
EPICS_CAS_IGNORE_ADDR_LIST correctly you should be protected against
loops though.

HTH,

- Andrew

-- 
Arguing for surveillance because you have nothing to hide is no
different than making the claim, "I don't care about freedom of
speech because I have nothing to say." -- Edward Snowdon

References:
Why do I need to prevent looping when deploying CA gateway Wang, Lin

Navigate by Date:
Prev: RE: GeniCam support for CamLink cameras Mark Rivers
Next: Listen on UDP socket for device message Jörn Dreyer
Index: 1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  <20172018  2019  2020  2021  2022  2023  2024 
Navigate by Thread:
Prev: Why do I need to prevent looping when deploying CA gateway Wang, Lin
Next: Listen on UDP socket for device message Jörn Dreyer
Index: 1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  <20172018  2019  2020  2021  2022  2023  2024 
ANJ, 21 Dec 2017 Valid HTML 4.01! · Home · News · About · Base · Modules · Extensions · Distributions · Download ·
· Search · EPICS V4 · IRMIS · Talk · Bugs · Documents · Links · Licensing ·