My hosted FreeBSD server is configured to use an IPv6 tunnel provided by Hurricane Electric. The tunnel interface is set up as follows:
The MTU of the outer IPv4 connection is 1500, so this tunnel interface's MTU of 1480 should be fine. However, when I attempt to ping6(8) the peer at the other end of the tunnel with a ping packet that should be exactly 1480 bytes in length, the outgoing request is chopped into two fragments:
Does anyone know the reason for this?
T.I.A.
Code:
gif0: flags=8151<UP,POINTOPOINT,RUNNING,PROMISC,MULTICAST> metric 0 mtu [red]1480[/red]
tunnel inet 31.193.132.199 --> 216.66.80.26
inet6 fe80::be30:5bff:feda:b396%gif0 prefixlen 64 scopeid 0x6
inet6 2001:470:1f08:84f::2 --> 2001:470:1f08:84f::1 prefixlen 128
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
options=1<ACCEPT_REV_ETHIP_VER>
Code:
# ping6 -c 1 -s 1432 2001:470:1f08:84f::1
PING6([red]1480[/red]=40+8+1432 bytes) 2001:470:1f08:84f::2 --> 2001:470:1f08:84f::1
1440 bytes from 2001:470:1f08:84f::1, icmp_seq=0 hlim=64 time=1.491 ms
--- 2001:470:1f08:84f::1 ping6 statistics ---
1 packets transmitted, 1 packets received, 0.0% packet loss
round-trip min/avg/max/std-dev = 1.491/1.491/1.491/0.000 ms
Code:
(tcpdump output)
13:37:09.892415 IP6 2001:470:1f08:84f::2 > 2001:470:1f08:84f::1: frag (0|1232) ICMP6, echo request, seq 0, length 1232
13:37:09.892424 IP6 2001:470:1f08:84f::2 > 2001:470:1f08:84f::1: frag (1232|208)
13:37:09.893870 IP6 2001:470:1f08:84f::1 > 2001:470:1f08:84f::2: ICMP6, echo reply, seq 0, length 1440
Does anyone know the reason for this?
T.I.A.