FreeBSD 5.2.1 - Bridging problems

[Kevin Roettger]

Hello,

I'm trying to setup a bridge on my FreeBSD box as follows:
3 NIC's: 
- A realtek plugged into a ADSL modem (rl0), this one is not part of 
the 
bridge
- Two 3Com 3c905C: xl0 works for months without problems and is 
connected to 
the LAN. The second card (xl1) has just been added. I'd like to connect 
another part of the LAN on it, so I thought bridging would be good.
The machine hosting the bridge is my internet router, so every machine 
on the 
LAN has this machine as router. xl0 has an IP, xl1 has not (the 
handbook says 
better not to give an IP to the second NIC)
I've set up the bridge as mentioned in the handbook:
net.link.ether.bridge.enable=1
net.link.ether.bridge.config=xl0,xl1
net.link.ether.bridge.ipfw=1
...all this in sysctl.conf. The module bridge.ko is loaded too, so 
everything 
should work fine.
Here an excerpt of ifconfig:

xl0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
        options=b<RXCSUM,TXCSUM,VLAN_MTU>
        inet6 fe80::210:5aff:fea6:4f65%xl0 prefixlen 64 scopeid 0x1 
        inet 10.0.0.1 netmask 0xffffff00 broadcast 10.0.0.255
        ether 00:10:5a:a6:4f:65
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active
xl1: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
        options=b<RXCSUM,TXCSUM,VLAN_MTU>
        inet6 fe80::20a:5eff:fe45:b152%xl1 prefixlen 64 scopeid 0x3 
        ether 00:0a:5e:45:b1:52
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active

So here's the problem: any client connected to xl0 can reach the 
clients on 
xl1 and vice-versa (this is good, yes), but NO way to see nor ping the 
router 
itself when trying from xl1!!! I believe this is very strange since the 
packets from xl1-side to xl0-side go thru the router.
xl0-side clients CAN ping and access the router, xl1-side clients 
cannot.
An 'arp -an' run on the router shows all xl0 clients, but nothing of 
xl1-sided clients. xl1-side clients have the same network config as the 
xl0 
ones, obviously.

Any clues really welcome! Thanks in advance.

Kevin