one subnet forwards and one does not ??

All,

The system is a FC1 box with three nets; 2 subnets that should be forwarded and
one uplink (don't know the name for that link)

The vmnet8 works correctly and support forwarding.

usb0 does not forward.

This is the center box routing table:

[root@600e 3.3.6pre1]# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
172.16.54.0 * 255.255.255.0 U 0 0 0 vmnet8
192.168.129.0 * 255.255.255.0 U 0 0 0 usb0
10.0.0.0 * 255.255.255.0 U 0 0 0 eth0
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default 10.0.0.1 0.0.0.0 UG 0 0 0 eth0

This is the routing table for the box that does not forward.
(I don't know why lo does not list, it is up)

# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.129.0 * 255.255.255.0 U 0 0 0 usbd0
default 192.168.129.1 0.0.0.0 UG 0 0 0 usbd0

This is the ifconfig entry for the port that does not forward. The interface
works to the center box.

usb0 Link encap:Ethernet HWaddr C6:CD:17:14:33:51
inet addr:192.168.129.1 Bcast:192.168.129.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:8983 errors:0 dropped:0 overruns:0 frame:0
TX packets:7090 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3652085 (3.4 Mb) TX bytes:558028 (544.9 Kb)

The systems uses a simple 4 line ipchains script that allows everything and
enables masq.

I do not see why this does not work. What can I try? Thanks,