Hi,
Back to this issue:
Setup:
Source: Linux box: 2a02:27d0:100:115:6000::200
Destination: OpenBSD 5.9-stable box: 2a02:27d0:116::3
Source#: ping6 -M do -s 1232 2a02:27d0:100:114::3
PING 2a02:27d0:100:114::3(2a02:27d0:100:114::3) 1232 data bytes
1240 bytes from 2a02:27d0:100:114::3: icmp_seq=1 ttl=63 time=0.224 ms
...
1240 bytes from 2a02:27d0:100:114::3: icmp_seq=4 ttl=63 time=0.274 ms
^C
--- 2a02:27d0:100:114::3 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 2998ms
rtt min/avg/max/mdev = 0.203/0.241/0.274/0.034 ms
Destination#: tcpdump -ni trunk0 host 2a02:27d0:100:115:6000::200
tcpdump: listening on trunk0, link-type EN10MB
16:26:22.236667 2a02:27d0:100:115:6000::200 > 2a02:27d0:100:114::3:
icmp6: echo request [flowlabel 0x9d84e]
16:26:22.236684 2a02:27d0:100:114::3 > 2a02:27d0:100:115:6000::200:
icmp6: echo reply
16:26:23.235712 2a02:27d0:100:115:6000::200 > 2a02:27d0:100:114::3:
icmp6: echo request [flowlabel 0x9d84e]
16:26:23.235732 2a02:27d0:100:114::3 > 2a02:27d0:100:115:6000::200:
icmp6: echo reply
16:26:24.234770 2a02:27d0:100:115:6000::200 > 2a02:27d0:100:114::3:
icmp6: echo request [flowlabel 0x9d84e]
16:26:24.234786 2a02:27d0:100:114::3 > 2a02:27d0:100:115:6000::200:
icmp6: echo reply
Now when increasing to 1233 data bytes:
Source#: ping6 -M do -s 1233 2a02:27d0:100:114::3
PING 2a02:27d0:100:114::3(2a02:27d0:100:114::3) 1233 data bytes
1241 bytes from 2a02:27d0:100:114::3: icmp_seq=1 ttl=63 time=0.212 ms
...
1241 bytes from 2a02:27d0:100:114::3: icmp_seq=12 ttl=63 time=0.232 ms
^C
--- 2a02:27d0:100:114::3 ping statistics ---
12 packets transmitted, 12 received, 0% packet loss, time 10998ms
rtt min/avg/max/mdev = 0.206/0.236/0.342/0.043 ms
Destination#: tcpdump -ni trunk0 host 2a02:27d0:100:115:6000::200
16:28:23.922257 2a02:27d0:100:115:6000::200 > 2a02:27d0:100:114::3:
icmp6: echo request [flowlabel 0x9d84e]
16:28:23.922284 2a02:27d0:100:114::3 > 2a02:27d0:100:115:6000::200: frag
(0x11cd00dd:1232@0+) icmp6: echo reply
16:28:23.922289 2a02:27d0:100:114::3 > 2a02:27d0:100:115:6000::200: frag
(0x11cd00dd:9@1232)
16:28:24.921229 2a02:27d0:100:115:6000::200 > 2a02:27d0:100:114::3:
icmp6: echo request [flowlabel 0x9d84e]
16:28:24.921256 2a02:27d0:100:114::3 > 2a02:27d0:100:115:6000::200: frag
(0x1be2a72d:1232@0+) icmp6: echo reply
16:28:24.921260 2a02:27d0:100:114::3 > 2a02:27d0:100:115:6000::200: frag
(0x1be2a72d:9@1232)
16:28:25.920252 2a02:27d0:100:115:6000::200 > 2a02:27d0:100:114::3:
icmp6: echo request [flowlabel 0x9d84e]
16:28:25.920290 2a02:27d0:100:114::3 > 2a02:27d0:100:115:6000::200: frag
(0x15850f70:1232@0+) icmp6: echo reply
16:28:25.920294 2a02:27d0:100:114::3 > 2a02:27d0:100:115:6000::200: frag
(0x15850f70:9@1232)
16:28:26.919167 2a02:27d0:100:115:6000::200 > 2a02:27d0:100:114::3:
icmp6: echo request [flowlabel 0x9d84e]
16:28:26.919194 2a02:27d0:100:114::3 > 2a02:27d0:100:115:6000::200: frag
(0x30d81daa:1232@0+) icmp6: echo reply
16:28:26.919200 2a02:27d0:100:114::3 > 2a02:27d0:100:115:6000::200: frag
(0x30d81daa:9@1232)
Sounds like replies are fragmented.
Please note trunk0 is composed of one em and one bnx interface:
trunk0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
lladdr 00:1b:21:b5:2a:8d
priority: 0
trunk: trunkproto lacp
trunk id: [(8000,00:1b:21:b5:2a:8d,4074,0000,0000),
(007F,64:87:88:bc:db:00,0006,0000,0000)]
trunkport bnx2 active,collecting,distributing
trunkport em3 active,collecting,distributing
groups: trunk
media: Ethernet autoselect
status: active
Am I mistaken on something, or is this behavior perfectly normal ?
Please note # tracepath6 from the linux box to the openbsd one reports:
Resume: pmtu 1500 hops 2 back 2
Thanks
Laurent
