8.1 em alias changes MAC

[Charles Sprickman]

Hello,

I've run into an odd problem on an 8.1 amd64 box (still running GENERIC) 
with aliases on the em interface.

Config is very simple:

em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
         options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
         ether 00:14:22:b1:54:18
         inet 10.3.2.233 netmask 0xffffff00 broadcast 10.3.2.255
         inet 10.3.2.234 netmask 0xffffffff broadcast 10.3.2.234
         media: Ethernet autoselect (100baseTX <full-duplex>)
         status: active

One main IP and one alias.

The main IP is not giving me any issues, but the alias seems to fall off 
the network after about 20 minutes or so.  Connectivity just drops.  I'd 
initially thought something else had that IP, but that's not the case.

Here's what another box sees before the problem starts:

? (10.3.2.233) at 00:14:22:b1:54:18 on sis0 [ethernet]
? (10.3.2.234) at 00:14:22:b1:54:18 on sis0 [ethernet]

And then after:

? (10.3.2.233) at 00:14:22:b1:54:18 on sis0 [ethernet]
? (10.3.2.234) at 00:14:22:b1:54:1a on sis0 [ethernet]

Note that the MAC for alias has changed...  I'm seeing no "xx.xx.xx  is 
using my IP" and I also know I've only got one other box with an em 
interface in the entire place and it's MAC is 00:30:48:28:87:16.

All the other hosts log this:

Aug 16 03:02:50 media kernel: arp: 10.3.2.234 moved from 00:14:22:b1:54:18 
to 00:14:22:b1:54:1a on em0

Deleting and re-adding the alias works for a bit, then this happens again.

Any ideas?

pciconf and dmesg snippet below.

Thanks,

Charles

em0: <Intel(R) PRO/1000 Legacy Network Connection 1.0.1> port 
0xecc0-0xecff mem 0xfe9e0000-0xfe9fffff irq 32 at device 4.0 on pci2
em0: [FILTER]
em0: Ethernet address: 00:14:22:b1:54:18

em0 at pci0:2:4:0: class=0x020000 card=0x019a1028 chip=0x10768086 rev=0x05 
hdr=0x00
     vendor     = 'Intel Corporation'
     device     = 'Gigabit Ethernet Controller (82541EI)'
     class      = network
     subclass   = ethernet
em1 at pci0:4:3:0: class=0x020000 card=0x019a1028 chip=0x10768086 rev=0x05 
hdr=0x00
     vendor     = 'Intel Corporation'
     device     = 'Gigabit Ethernet Controller (82541EI)'
     class      = network
     subclass   = ethernet