Hello Sirs,


I have the folowing setup: a ring of 6 netbsd-2-0-2 routers all having 
some fxp(4) and the folowing wm(4) GigE cards:

wm0 at pci2 dev 1 function 0: Intel i82547EI 1000BASE-T Ethernet, rev. 0
wm0: interrupting at irq 10
wm0: Communication Streaming Architecture
wm0: using 82547 Tx FIFO stall work-around
wm0: 65536 word (16 address bits) SPI EEPROM
wm0: Ethernet address 00:11:11:7e:24:f4
igphy0 at wm0 phy 1: Intel IGP01E1000 Gigabit PHY, rev. 0
igphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, 1000baseT, 
1000baseT-FDX, auto

or

wm1 at pci3 dev 0 function 0: Intel i82541GI 1000BASE-T Ethernet, rev. 0
wm1: interrupting at irq 3
wm1: 32-bit 33MHz PCI bus
wm1: 64 word (6 address bits) MicroWire EEPROM
wm1: Ethernet address 00:0e:0c:64:5c:1a
igphy1 at wm1 phy 1: Intel IGP01E1000 Gigabit PHY, rev. 0
igphy1: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, 1000baseT, 
1000baseT-FDX, auto

They are plugged in a manageable switch and have ips from a /27 network 
assigned and they route via bgp/ospf .

Having a high load of traffic the ip/tcp/udp checksuming was needed on 
those wm(4). But once enabled there was a drastic upload rate reduction, 
from 300Mbps to 100Mbps.

By monitoring the switch FDB i noticed new mac-addresses appearing:

1 	default 	00-11-11-7E-24-F4 	2 	Dynamic
1 	default 	00-11-11-7E-24-F8 	2 	Dynamic


the first mac-address belongs to the first wm0 from up.
What is odd is that the second mac appearing on the same port where wm0 
is plugged in_ is from an fxp on the same server which doesn't have any 
link with the switch. So this mac-address shouldn't be advertised. The 
tcpdump -e on a server plugged in the switch too but not routing 
anything shows those odd packets originating with mac-addresses from 
behind the switch network/routers which are of course blackholed.

Any other information needed (dmesgs, ifconfigs) is available upon request.