kernel arp errors

Robert Fitzpatrick robert at
Wed Mar 10 17:33:19 PST 2004

On Wed, 2004-03-10 at 10:54, Robert Fitzpatrick wrote:
> I am running 5.2.1 with two NIC's, both connected to a Cisco switch with
> a Cisco router also connected to the switch for Internet connectivity.
> There are 5 eth ports on the router, one of them with an address
> assigned of and another with, the
> other eth ports are the ISP connection and other one other subnet. One
> port not used. On the FreeBSD host, the two NIC's are assigned with em0
> as and em1 as These are the
> messages I am getting over and over, note the IP's are those of the
> router:
> Mar 10 10:35:49 esmtp kernel: arp: is on em0 but got
> reply from 00:30:94:32:94:30 on em1
> Mar 10 10:35:51 esmtp kernel: arp: is on em1 but got reply from 00:30:94:32:94:32 on em0
> I know I can do some config on the router to isolate subnet traffic to
> ports, but haven't done this, yet. Is this my problem or can someone
> help me understand what is going on?

Replying to myself since posting the first time. I had the need to add
another IP address in the same subnet as the existing IP on em0, a
virtual IP (em0:0?). I try to add an IP to the em0 and it gives me an
error, see below, but seems to work fine on em1:

esmtp# ifconfig em1 alias
esmtp# ifconfig -a
        inet netmask 0xfffffff0 broadcast
        inet6 fe80::230:48ff:fe29:847c%em0 prefixlen 64 scopeid 0x1
        ether 00:30:48:29:84:7c
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active
        inet netmask 0xfffffff8 broadcast
        inet6 fe80::230:48ff:fe29:847d%em1 prefixlen 64 scopeid 0x2
        inet netmask 0xff000000 broadcast
        ether 00:30:48:29:84:7d
        media: Ethernet autoselect
        status: no carrier
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
        inet netmask 0xff000000
        inet6 ::1 prefixlen 128
        inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3
esmtp# ifconfig em1 alias
ifconfig: ioctl (SIOCAIFADDR): File exists

Afterwards, now I am getting this message in the syslog similar to the
others I originally posted:

Mar 10 19:39:24 esmtp kernel: arp: is on lo0 but got
reply from 00:30:48:29:84:7c on em1

Can anyone help me understand what I'm doing wrong?


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