On Thu, Jun 03, 2004 at 12:50:56 +0900, Jun-ichiro itojun Hagino wrote:

>  5  sh3.iijlab.net  2.35 ms
> 	| MTU=1280
>  6  garlic  4.161 ms

Is it the standard traceroute6 that prints the mtu?

One more datapoint. Ping6 packets are sent with the lower mtu, while udp
is sent with the higher mtu. I guess I have to see what happens in
udp6_output.

06:02:25.763764 2001:888:1777:0:260:8ff:fed1:a403 > 2001:7b8:206:1:240:f4ff:fe37:8232: frag (0xdf9c8710:0|1232) icmp6: echo request (len 1240, hlim 64)
06:02:25.763899 2001:888:1777:0:260:8ff:fed1:a403 > 2001:7b8:206:1:240:f4ff:fe37:8232: frag (0xdf9c8710:1232|776) (len 784, hlim 64)
06:02:25.839829 2001:7b8:206:1:240:f4ff:fe37:8232 > 2001:888:1777:0:260:8ff:fed1:a403: frag (0x000035dd:0|1232) icmp6: echo reply (len 1240, hlim 58)
06:02:25.842503 2001:7b8:206:1:240:f4ff:fe37:8232 > 2001:888:1777:0:260:8ff:fed1:a403: frag (0x000035dd:1232|776) (len 784, hlim 58)
06:02:27.158391 2001:7b8:206:1:240:f4ff:fe37:8232.49154 > 2001:888:1777:0:260:8ff:fed1:a403.53: [udp sum ok]  41397+ [1au] AAAA? foo.rvdp.org. ar: . OPT UDPsize=4096 (41) [flowlabel 0x65053] (len 49, hlim 58)
06:02:27.174151 2001:888:1777:0:260:8ff:fed1:a403 > 2001:7b8:206:1:240:f4ff:fe37:8232: frag (0xbc5f9df3:0|1448) 53 > 49154:  41397 q: AAAA? foo.rvdp.org. 128/2/3 foo.rvdp.org. AAAA dead:beef::, foo.rvdp.org. AAAA dead:beef::1, foo.rvdp.org. AAAA dead:beef::2, foo.rvdp.org. AAAA dead:beef::3, .... (large output)
06:02:27.174303 2001:888:1777:0:260:8ff:fed1:a403 > 2001:7b8:206:1:240:f4ff:fe37:8232: frag (0xbc5f9df3:1448|1448) (len 1456, hlim 64)
06:02:27.174324 2001:888:1777:0:260:8ff:fed1:a403 > 2001:7b8:206:1:240:f4ff:fe37:8232: frag (0xbc5f9df3:2896|831) (len 839, hlim 64)
06:02:27.177992 2001:888:1777::1 > 2001:888:1777:0:260:8ff:fed1:a403: icmp6: too big 1280 (len 1240, hlim 64)
06:02:27.179103 2001:888:1777::1 > 2001:888:1777:0:260:8ff:fed1:a403: icmp6: too big 1280 (len 1240, hlim 64)
06:02:30.773880 fe80::260:8ff:fed1:a403 > fe80::220:afff:fec6:4faa: icmp6: neighbor sol: who has fe80::220:afff:fec6:4faa(src lladdr: 00:60:08:d1:a4:03) (len 32, hlim 255)
06:02:30.774632 fe80::220:afff:fec6:4faa > fe80::260:8ff:fed1:a403: icmp6: neighbor adv: tgt is fe80::220:afff:fec6:4faa(RS) (len 24, hlim 255)
06:02:32.155293 2001:7b8:206:1:240:f4ff:fe37:8232.49154 > 2001:888:1777:0:260:8ff:fed1:a403.53: [udp sum ok]  41397+ [1au] AAAA? foo.rvdp.org. ar: . OPT UDPsize=4096 (41) [flowlabel 0x65053] (len 49, hlim 58)
06:02:32.171427 2001:888:1777:0:260:8ff:fed1:a403 > 2001:7b8:206:1:240:f4ff:fe37:8232: frag (0xd6fdb6f8:0|1448) 53 > 49154:  41397 q: AAAA? foo.rvdp.org. 128/2/3 foo.rvdp.org. AAAA dead:beef::, foo.rvdp.org. AAAA dead:beef::1, foo.rvdp.org. AAAA dead:beef::2, foo.rvdp.org. AAAA dead:beef::3, (large output)
06:02:32.171585 2001:888:1777:0:260:8ff:fed1:a403 > 2001:7b8:206:1:240:f4ff:fe37:8232: frag (0xd6fdb6f8:1448|1448) (len 1456, hlim 64)
06:02:32.171605 2001:888:1777:0:260:8ff:fed1:a403 > 2001:7b8:206:1:240:f4ff:fe37:8232: frag (0xd6fdb6f8:2896|831) (len 839, hlim 64)
06:02:32.175165 2001:888:1777::1 > 2001:888:1777:0:260:8ff:fed1:a403: icmp6: too big 1280 (len 1240, hlim 64)
06:02:32.176235 2001:888:1777::1 > 2001:888:1777:0:260:8ff:fed1:a403: icmp6: too big 1280 (len 1240, hlim 64)
^C
141 packets received by filter
0 packets dropped by kernel

	rvdp