I'm trying to track down an entry that keeps showing up in my
system logs. It appears on all of my machines, and it doesn't
matter whether it's a server or client machine. This one happens to
be from one of my servers. All machines are 10.4.6 In the space of
45 minutes I have had over 65 entries for this.
May 8 18:36:15 adultserver kernel: arp: 10.2.0.1 moved from
00:00:5e:00:01:02 to 00:0e:62:4e:c0:02 on en0
May 8 18:36:16 adultserver kernel: arp: 10.2.0.1 moved from
00:0e:62:4e:c0:02 to 00:00:5e:00:01:02 on en0
Now the 10.2.0.1 address is from the router
According to http://standards.ieee.org/regauth/oui/index.shtml the
00-0e-62 is registered to Nortel Networks, which makes sense as that
is what our main router is. The 00-00-5e is apparently registered
to USC Information Sciences Inst. I ran ethereal on the network and
received this back:
Source: IETF-VRRP-virtual-router-VRID_02 (00:00:5e:00:01:02) I
didn't see the 00:0e:62:4e:c0:02 address.
Now, I searched the archives and, in a posting from May 23 2004
from Dan Shoop, found out that this might be happening due to the
(1) The machine has multiple NIs and it's switch the NI it's using.
(2) The IP address has failed over to another machine
(3) The IP address is dynamically assigned (say by DHCP) and a new
system has gotten this IP.
(4) You're network is fuxored and you have more than one machine
with the same address and both are advertising the same IP.
So, I ran an arp -a from my local box, and came back with this:
? (10.2.0.1) at 0:0:5e:0:1:2 on en0 [ethernet]
and then I ran an netstat -rn and received this back:
Does anyone have an idea on why it is flipping back and forth
between the two MAC addresses? I would like to get this fixed so
the router is not always switching between the two MAC addresses. I
have mentioned this to the other network admin, but he has told me
that he doesn't see it happening on his Windows machines, but as far
as I can tell it seems to be coming from the main router. I've been
told that I should only be seeing the 00:00:5e:00:01:02 address.
Another important question is how much is this impacting my
network performance if the main router is constantly switching back
and forth like this?
Who has the offending MAC addresses that this IP is flip flopping over?
You may also have a MAC that appears on two different network segments.
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