Date: Wed, 12 Dec 2012 22:50:42 -0500 From: Zaphod Beeblebrox <zbeeble@gmail.com> To: FreeBSD Net <freebsd-net@freebsd.org> Subject: ipv6 route ignores MTU. Message-ID: <CACpH0MdbHa%2BeYoE2XuaXkSUMOvkhL9bQkhFOgTtj1gOzbacQaw@mail.gmail.com>
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On a:
FreeBSD virtual.accountingreality.com 9.1-RC2 FreeBSD 9.1-RC2 #6 r241240:
Sat Oct 6 01:43:35 EDT 2012
root@virtual.accountingreality.com:/usr/obj/usr/src/sys/VRA
amd64
I have set a high MTU:
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9014
options=4019b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,VLAN_HWTSO>
ether 00:15:17:0d:04:a8
inet x.y.z.q netmask 0xffffffe0 broadcast x.y.z.q1
inet6 fe80::215:17ff:fe0d:4a8%em0 prefixlen 64 scopeid 0x5
inet6 2001:1928:1::52 prefixlen 64
inet 192.168.221.2 netmask 0xffffff00 broadcast 192.168.221.255
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
media: Ethernet autoselect (1000baseT <full-duplex>)
status: active
curiously, although:
[1:2:301]root@virtual:~> route -n get 192.168.221.84
route to: 192.168.221.84
destination: 192.168.221.0
mask: 255.255.255.0
interface: em0
flags: <UP,DONE>
recvpipe sendpipe ssthresh rtt,msec mtu weight expire
0 0 0 0 9014 1 0
shows the correct MTU,
[1:5:304]root@virtual:~> route -n get -inet6 2001:1928:1::84
route to: 2001:1928:1::84
destination: 2001:1928:1::
mask: ffff:ffff:ffff:ffff::
interface: em0
flags: <UP,DONE>
recvpipe sendpipe ssthresh rtt,msec mtu weight expire
0 0 0 0 1500 1 0
shows the wrong MTU.
The MTU in this case is set in the ifconfig_em0 rc.conf entry and the
machine has been rebooted.
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