From: Webpro (pchandyman@pacbell.net)
Date: Tue Jul 13 2004 - 16:14:51 EDT
More info:
Two other machines on the same subnet do not run
into this problem. Also, it happens more frequently
when the load on the machine increases (machine
requesting the arp, not the destination). The machine
is not overloaded.
I have a simple arp test shell script running on
four machines. The script, forever loop, arps (as
below) then sleeps a second. If the problem occurs,
it is on a 5 minute cycle (arp cache timeout cycle),
has incomplete for 40 seconds, then is OK. Sometimes,
it extends to 80 seconds, occasionally 120 seconds,
and rarely 160 seconds. This problem has only been
seen between machine B and machine A. More
investigation is needed to see if it is happening
elsewhere and how often. Reboots do not solve the
problem, netstat -ns has no anomalies, kstat -m xxx -i
x has no anomalies.
Machine B arps Machine A (Incomplete)
Machine C arps Machine A OK
Machine D arps Machine A OK
Machine A arps Machien B OK
Webpro <pchandyman@pacbell.net> wrote:
I have narrowed down some problems to a server
having
and "incomplete" status. This state can last a
couple
minutes.
As the ARP cache times out and a new ARP request for
the host is sent, there appears to be a 40 second
timeout (I am unable to locate a way to change this)
and the arp -a status for the host is "U"
incomplete.
After which time, another arp is sent and the
process
continues until a response is received.
Theory is that the arp reply is not making it back
to
the server, but I cannot duplicate this state by
arping a non-existant host on the same subnet. In
this case, I the status is always "no entry".
My theory is that the entry must have existed in the
arp cache at the same time it is timing out, a new
arp
for the host is sent and the entry does not get
deleted, just status changed to incomplete waiting
for
a response from the host.
I am now tired from reading numerous google hits
saying the same thing. Does anyone have some
experience with arp and this type of challenge?
Thanks,
Joe
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