em driver - issue #2

[Matthew Dillon]

:Ok, now thats its not crashing anymore, on to the next problem. After
:starting the traffic generator, I now get the expected 
:
:"All mbuf clusters exhausted, please see tuning(7)"
:
:message. However it apparently locks up the controller, or at least
:it doesn't recover as expected. Once I stop the traffic generator,
:other interfaces on the dragonfly machine operate normally, but
:the one that was being pounded cannot receive. If I initiate a 
:ping from the dfly box out of the problem controller, then it starts
:working ok. I also get a
:
:"Limiting ICMP unreach response from 11768 to 200 pps"
:
:which implies that quite a few packets get "stuck" somewhere and
:are all released at once when a transmit is initiated, since
:the traffic had stopped arriving long before.
:
:I'll have a chance tomorrow perhaps to dig a bit deeper, but any ideas
:about what might have been changed to cause this  (as this isnt a 
:problem in freebsd) would be helpful. I can also try it on an fxp
:interface to see if its an em problem or a system-wide problem.

    This sounds like an ARP issue.  If the machine is being pounded
    to the point where it cannot ARP IP addresses, then packets will
    be queued both on the machine awaiting arp or on other machines
    trying to arp the one being pounded.

					-Matt
					Matthew Dillon 
					<dillon at xxxxxxxxxxxxx>