Hi! I have a trouble with a ipv6 path mtu testing.
The environments are as follows.

PC A (fedora) ------------------------ LINUX ROUTER
(kernel 2.6.15, network driver sk98lin)
They are connected through switch.
And their address is IPv6 Global address.

Interface of PC A is set with MTU 1500, default value.(ifconfig eth0 mtu 1500)
Interface of LINUX ROUTER is set with 1280. (ifconfig eth0 mtu 1280)

When I execute "ping6 -c 4 -S 1500 address_of_LINUXROUTER" in PC A,
there's no reply from LINUX ROUTER.
When I see network packet with tcpdump in LINUX ROUTER, there's only fragmented packet. There's no echo request packet (frag 0|144.

***** tcpdump result ****
16:55:57.201543 3ffe:501:ffff:100::10 > 3ffe:501:ffff:100::20: frag (1448|60)
16:55:58.211133 3ffe:501:ffff:100::10 > 3ffe:501:ffff:100::20: frag (1448|60)
16:55:59.211167 3ffe:501:ffff:100::10 > 3ffe:501:ffff:100::20: frag (1448|60)
16:56:00.211188 3ffe:501:ffff:100::10 > 3ffe:501:ffff:100::20: frag (1448|60)
**********

It seems that network driver does not process packet which is bigger than MTU(1280). But there's no dropped packet in ifconfig result.

********** ifconfig eth0 of LINUX ROUTER ************
UP BROADCAST RUNNING MULTICAST MTU:1280 Metric:1
RX packets:11 errors:0 dropped:0 overruns:0 frame:0
TX packets:5 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:6822 (6.6 KiB) TX bytes:382 (382.0 b)
Interrupt:10 Memory:d8320000-0
***********************************************

How can I fix this problem? Is this a network driver(sk98lin) problem?
{I do the same test with another LINUX ROUTERS(1. 2.6.18, e1000, 2. 2.4.31, e100), there's no problem.
}

Please help me.....