Experimental Physics and Industrial Control System
> ../online_notify.c: CA beacon routing (connect to "142.90.127.255:9011")
> error was "S_errno_ECONNREFUSED"
It might be possible to receive that error indication if a destination host
returned an ICMP error message such as DestinationPortUnreachable because
they receive a broadcasted UDP message with a destination address that they
believe to be on the wrong subnet. Note that since this is a broadcast
address there might be many potentially miss configured destination hosts
(that might potentially send you an ICMP error message reply).
I believe that IP kernels are not supposed to return ICMP error messages in
response to broadcasts, but since presumably the network mask of the rogue
host might be miss-configured then you can see what might happen if we
didn't have a terribly robust implementation of the IP kernel.
I would use a program like etherfind, tcpdump, ethereal, etc to monitor ICMP
traffic with intent of discovering its source.
If you have too many hosts sending incorrect ICMP error responses then this
can definitely interfere with CA's UDP based name resolution, but presumably
not with TCP circuits once they successfully connect.
This might also occur because there is no route to address "142.90.127.255"
on your IOC. This should be the broadcast address of the local LAN. The host
part of a broadcast address is all ones. In this situation the local LAN's
network part presumably is 142.90.96.0.
I would try ping-ing a host on the 142.90.96.0 subnet from the IOC's console
to verify that it routes correctly.
I would also look at the following:
A) View the route configuration using routeShow
B) View the broadcast address configuration and netmask using ifShow
Finally, I assume that you are aware that you are using a non-standard
beacon destination port for this IOC.
Jeff
> -----Original Message-----
> From: Evgeniy Tikhomolov [mailto:[email protected]]
> Sent: Thursday, March 09, 2006 11:04 AM
> To: EPICS Tech-Talk
> Subject: CA beacon routing problem
>
> We were happily running EPICS release 3.14.6 for more than one year on
> our system with mv162.
>
> Suddenly ...
>
> Actually, not so suddenly the network mask for TRIUMF site had been
> changed from 255.255.0.0 to 255.255.224.0.
> We also changed the network mask on IOC and our Solaris servers.
> And after that, suddenly we began to get on our IOC console the
> following error message:
>
> ../online_notify.c: CA beacon routing (connect to "142.90.127.255:9011")
> error was "S_errno_ECONNREFUSED"
>
> After some time the connection between IOC and dm-screens is lost. If we
> set netmask to previous 255.255.0.0. in error message 127 is replaced by
> 255.
>
> Can somebody explain the reasons for appearance of such error message?
>
> Temporary we solved the problem by placing IOC behind firewall. In this
> case the error message dissappears and everything is like in old good
days.
>
> Thanks,
> Evgeniy
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