[Click] KernelTap problem

[Hashimoto]

Hello.
I have KernelTap problem in Click.

My Environment is
 Click : 1.6.0
 OS : FreeBSD 7.0
 host1 : 192.168.1.2
 host2 : 192.168.1.3

My program is a very simple VPN using UDP socket.

conf1 (Click configuration file for host1)
tap :: KernelTap(10.0.0.1/8);
sock :: Socket(UDP, 192.168.1.2, 50000, 192.168.1.1, 50000, CLIENT true);
tap -> sock;
sock -> tap;

conf2 (Click configuration file for host2)
tap :: KernelTap(10.0.0.2/8);
sock :: Socket(UDP, 192.168.1.1, 50000, 192.168.1.2, 50000, CLIENT true);
tap -> sock;
sock -> tap;

Then, I execute Click like this.
host1 # click conf1
host2 # click conf2

I can communicate each other with "small" data.
host1 $ ping 10.0.0.2 -> get reply
host2 $ ping 10.0.0.1 -> get reply
host1 $ fetch http://10.0.0.2/some_small_data -> can fetch

But, I cannot communicate with "large" data.
host1 $ fetch http://10.0.0.2/some_large_data (larger than 1434 Byte)
-> cannot fetch...

host1 $ ifconfig tap0
tap0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
      ether xx:xx:xx:xx:xx:xx
      inet 10.0.0.1 netmask 0xff000000 broadcast 10.255.255.255
      Opened by PID 13930

host2 $ ifconfig tap0
tap0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
      ether yy:yy:yy:yy:yy:yy
      inet 10.0.0.2 netmask 0xff000000 broadcast 10.255.255.255
      Opened by PID 47342

How can I fix this problem?
I think this problem has something to do with interface's MTU,
but I'm not sure.

Regards.

-- 
Hashimoto Kouki
hsmtkk at gmail.com