Experimental Physics and
Industrial Control System

"Mark Rivers" <[email protected]> · Wed, 24 Mar 2004 19:33:45 -0600

Jeff,

> The particular type of PPC SBC used at the SNS as been 
> observed to go into an ENOBUF error producing state when there is
shortage of 
> driver buffer pool. Dave Thompson has observed that an IOC can get
into 
> this state by sending large ping messages. CA routinely sends UDP
messages 
> with a 1472 byte payload. Here is an excerpt from his message on the
subject.

Thanks very much, that seems to be the problem.  If I do the following
on a Unix system (must be root to do it):
> ping -s 1500 -l 2000 x26a-vmecpu

pinging my PPC vxWorks system with 2000 1500-byte packets as fast as
possible then it immediately crashes the network on vxWorks.  This is
MVME2700 and Tornado 2.0.2. I start to get the messages:
iocx26a> CAC: error = "S_errno_ENOBUFS" sending UDP msg to
130.199.193.255:5064
CAC: error = "S_errno_ENOBUFS" sending UDP msg to 130.199.193.255:5064
..../online_notify.c: CA beacon (send to "130.199.193.255:5065") error was
"S_errno_ENOBUFS"
CAC: error = "S_errno_ENOBUFS" sending UDP msg to 130.199.193.255:5064

NFS no longer works, and I have to reboot.

These are exactly the symptoms the VME crates at Brookhaven were seeing
this afternoon.  I suspect someone or some virus is pounding on machines
on their subnet, and this is crashing the vxWorks network stack.

Mark

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System