Experimental Physics and
Industrial Control System

"Jeff Hill" <[email protected]> · Mon, 6 Aug 2007 09:57:04 -0600

Mike,

Only seeing the messages just after a boot _is_ a somewhat mysterious. It's
probably safe to deduce that there would be increased UDP traffic just after
a boot when all of the clients are connecting because they would need to
complete their name resolution requests (which occur over UDP). Nevertheless
there should be substantial TCP traffic after the clients connects and so
its hard to explain no damaged frames then (if that is in fact what is
occurring based on ifShow). It's possible that the UDP CRC error checking is
disabled while the TCP CRC checks remain enabled (that's possible with
kernel config as I recall)? Otherwise, perhaps there is a race condition in
the vxWorks IP kernel or in the CA server when the system starts up. I am
not aware of any issues like that with patched versions of R3.13.
Nevertheless many different issues have been fixed over the years in R3.14.
It might also be a good idea to verify that you have all of the patches from
WRS for your network interface driver.

Jeff

-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Laznovsky, Michael
Sent: Friday, August 03, 2007 4:09 PM
To: EPICS Tech Talk
Subject: RE: "invalid UDP request" during boot

It appears to work OK after boot.  The rack that this h/w is in is 
undergoing some changes, so there may have been some cables affected 
prior to these msgs appearing.  We'll keep an eye on it.

We only see these msgs right after iocInit()... is that a clue?

Mike

-----Original Message-----
From: Jeff Hill [mailto:[email protected]] 
Sent: Thursday, August 02, 2007 5:23 PM
To: Laznovsky, Michael; 'EPICS Tech Talk'
Subject: RE: "invalid UDP request" during boot

Hello Mike,

The CA UDP server spits out that message when it receives a datagram with
undecipherable protocol.

If there is substantial multi-bit damage in the datagram it can slip through
the UDP and Ethernet CRC checksum validations. Watch out for vxWorks
auto-negotiation problems with {10/100} and {full duplex/half duplex}
Ethernet that can occur if the vxWorks system is turned on before the switch
is. Also watch out for invalid termination and or branching of legacy coax
based Ethernet. There can also be intermittent issues with copper Ethernet
cables that pass close to electronic noise sources. Look for non-zero error
counts in the output from "ifShow".

Does the CA based communication function correctly after the IOC boots?

Jeff

-----Original Message-----

iocInit: All initialization complete
CAS: invalid (damaged?) UDP request from gtw01:46316 ?
CAS: invalid (damaged?) UDP request from gtw01:39871 ?
CAS: invalid (damaged?) UDP request from gtw01:46316 ?

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System