Experimental Physics and
Industrial Control System

Noboru Yamamoto <[email protected]> · Wed, 22 Dec 1999 11:22:11 +0900

Hi Jeff,

Jeff Hill wrote:
> 
> Hi Noboru,
> 
> > Ocasionally, we receive the following message on IOC and some of our WS.
> >
> > CAC: post_msg(): Corrupt cmd in msg 5
> > ../iocinf.c: bad UDP msg from port=5064 addr=172.19.63.255
> >
> > It is definitely related to a call of ca_search. I (think) there is a
> program
> > other than CA server which uses the UDP port 5064 to accept connection on
> > our network. So, it is not the problem of CA library.
> 
> This is possible. Or it is also possible that in extreme situations
> that a damaged packet could, despite odds to the contrary, pass through
> the Ethernet and IP CRC checksum filters undetected. It is also possible
> that there is an undiscovered bug in CA that causes this. I reported some time
> back that I had seen a "bad UDP message" diagnostic when regression testing
> R3.14, but I have subsequently discovered that my efforts in R3.14 to make
> the CA libraries more robust went too far and I had eliminated support for
> an infrequently used protocol between the CA repeater and the CA client. After
> restoring portions of the code that I removed I no longer see this
> diagnostic,
> and so the cause of these "bad UDP message" diagnostics occasionally seen in
> R3.13 remains a mystery.
>
I observed a "bad UDP message" on VxWorks(5.3) and on Digital Unix(4.1)
but never 
observed it on HP-UX 10.2. 
Firstly I suspected a program running on HP-UX for this message. However,
even if NO program uses UDP port 5064 on HP-UX, we still have same error message
on OSF1 and VxWorks (and no error message on HP-UX).

> 
> This diagnostic appears to be quite rare. Any additional information that
> other sites in the collaboration can provide about the surrounding
> circumstances that might influence this situation are greatly appreciated.
> 
> 
> Jeff

Noboru

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System