Experimental Physics and
Industrial Control System

Benjamin Franksen <[email protected]> · Fri, 5 Apr 2013 16:21:06 +0200

Hello CA Experts

I have a strange problem with an IOC runnign EPICS base 3.14.8. Half an hour
ago, it suddenly started issuing error messages like

../online_notify.c: CA beacon (send to "193.149.12.255:5065") error was
"S_errno_ENOBUFS"

which I now get periodically (every few seconds).

Now, what is funny is that the IOC does not have any records on it. I have a
very similar IOC in the same network (same base version) that /does/ have
records on it and which does /not/ issue these messages.

There is probably some rogue CA client on the network that broadcasts name
resolution requests with a (too) high frequency (this is our development
network, not operation, fortunately), but I have not yet managed to find out
its IP address.

"casr 2" says

Channel Access Server V4.11
No clients connected.
UDP Server:
UDP 193.149.12.6:38238(): User="", V4.11, 0 Channels, Priority=0
        Task Id=0x1d31698, Socket FD
        Secs since last send 2853.75, Secs since last receive 1550.10
        Unprocessed request bytes, Undelivered response bytes=0
        State=up
        168 bytes allocated

There are currently 1176 bytes on the server's free list
7 client(s), 0 channel(s), 0 event(s) (monitors) 0 putNotify(s)
0 small buffers (16384 bytes ea), and 0 jumbo buffers (16408 bytes ea)
The server's resource id conversion table:
Bucket entries in use = 0 bytes in use = 16404
Bucket entries/hash id - mean = 0.000000 std dev = 0.000000 max = 0
The server's array size limit is 16408 bytes max
Channel Access Address List
193.149.12.255:5065

This is strange in and of itself, since it first says "No clients connected"
(which I expected, since there are no records) and then later "7
client(s),..." which I find disturbing.

So, if anyone has an idea what might be going on here I'd be glad for an
explanation. BTW, I restarted the IOC which silences the error messages for
some time (a few minutes, maybe) after which they start again.

How do I find rogue CA clients (if that causes the problem at all, maybe
something else is wrong)? Could network problems cause this? Is there maybe a
known bug in 3.14.8 that could explain this?

Cheers
--
Ben Franksen
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System