What can also cause this is simply network latency that is longer than your
timeout values (within xnmnsmpconf) for that node.   NetView pings the
device and waits the timeout/retry settings.   No ping response in that
time, so it marks the interface down.   Then finally a response does return
from the previous pings.  Netmon sees that ping response and changes the
status back to up.   You should be able to adjust the wait time and/or
retries and this should go away.

Kind regards,
Stephen Hochstetler              shochste AT us.ibm DOT com
International Technical Support Organization at IBM
11400 Burnet Road   Austin, TX  78758
Office - 512-838-6198 (t/l 678)       FAX - 512-838-6931
------------------------------------------------------------
http://www.redbooks.ibm.com