Experimental Physics and
Industrial Control System

"Dale L. Brewe" <[email protected]> · Wed, 25 Aug 1999 10:56:03 -0500

Chip

Well, something along these lines seems plausible, I guess, altho the
gateway has not changed, nor have the ioc parameters. However, these
problems surfaced a few days after a new main switch/router was installed.
Clearly the problem seems to be at a pretty basic level, as I have troubles
pinging the ioc with no CA clients running. I haven't found anything that
looks bad in either hardware or software. In the ioc startup, I have
routeAdd "0", "x.x.x.x" for our subnet gateway. Is this correct? It worked
before, but could the routers be acting differently for some reason?

Dale

At 08:08 AM 8/25/99 , Chip Watson wrote:

Dale,
Your problem is similar to one I tracked down at PSI. If you
have a gateway (default routing node) improperly set in the
boot parameters of the IOC, then the following scenario can
happen:
(1) the first client connects, but the ioc sends all traffic for
that client through the gateway
(2) the gateway eventually sends a message to the ioc telling it
what the correct ethernet address for that host is (it doesn't want
to carry traffic unnecessarily)
(3) the ioc mistakenly updates the gateway address instead of
installing an explicit host entry
(4) the second client connects, and the ioc attempts to route
all traffic through the gateway again, but now it uses the
"updated" address for the gateway, which is client one
(5) client one refuses to forward the packets (lazy, huh?), so
the ioc appears to drop off the net for everyone except the
first client to have connected
Log into the ioc via the console if you can, and you can watch
this scenario play out.  Then, check your boot parameters and
either fix or remove the gateway entry.
Chip

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Dale L. Brewe     PNC-CAT/U. of Washington
 ph: 630 252 0582         fax: 630 252 0580
 Mail:
 Argonne National Laboratory/APS
 Bldg 435E sector 20
 9700 S. Cass Ave.
 Argonne, IL 60439
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System