RELENG_6_3 ping and DUP packets

[Mike Andrews]

Chuck Swiger wrote:
> On Apr 10, 2008, at 1:58 PM, Damian Weber wrote:
>> But here is the problem, pinging the machine from remote gives
>>
>> A.B.C.X$ ping A.B.C.D
>> PING A.B.C.D (A.B.C.D): 56 data bytes
>> 64 bytes from A.B.C.D: icmp_seq=0 ttl=64 time=0.272 ms
>> 64 bytes from A.B.C.D: icmp_seq=0 ttl=255 time=0.391 ms (DUP!)
> 
> Please run "tcpdump -e icmp" on this box and repeat your testing.  It 
> will be most interesting to know whether you're seeing the same MAC 
> address....

I'm seeing the same thing on *one* of my RELENG_7 boxes, including the 
problem going away at 1481 bytes.

In my case, if I run "tcpdump -e icmp" on both the offending RELENG_7 
box and on the machine pinging it (tried with both a Mac Mini running 
Leopard on the same LAN, and a RELENG_7_0 box on the other side of a DSL 
line), the RELENG_7 box only shows a single reply packet going out, but 
the pinger shows two -- and both packets have the same (correct) mac 
address.

It does not happen with all of my RELENG_7 machines though...  just one 
of them...  even though all of them have the same motherboard chipset 
(Intel 3000) and NIC (em0).  I haven't figured out exactly when it 
started or what's different about that one machine.  It doesn't seem to 
hurt anything other than it's somewhat annoying and Nagios complains 
bitterly about it. :)