* Re: [Bugme-new] [Bug 15530] New: ipip6 MTU cannot be set lower than 1280
[not found] <bug-15530-10286@http.bugzilla.kernel.org/>
@ 2010-03-19 21:19 ` Andrew Morton
0 siblings, 0 replies; only message in thread
From: Andrew Morton @ 2010-03-19 21:19 UTC (permalink / raw)
To: netdev; +Cc: bugzilla-daemon, bugme-daemon, berni
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On Sat, 13 Mar 2010 14:38:54 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:
> http://bugzilla.kernel.org/show_bug.cgi?id=15530
>
> Summary: ipip6 MTU cannot be set lower than 1280
> Product: Networking
> Version: 2.5
> Kernel Version: 2.6.32
> Platform: All
> OS/Version: Linux
> Tree: Mainline
> Status: NEW
> Severity: low
> Priority: P1
> Component: IPV6
> AssignedTo: yoshfuji@linux-ipv6.org
> ReportedBy: berni@birkenwald.de
> Regression: No
>
>
> The (inner) MTU of a ipip6 (IPv4-in-IPv6) tunnel cannot be set below 1280,
> which is the minimum MTU in IPv6. However, there should be no IPv6 on the
> tunnel interface at all (ipip6 cannot transport it), so the IPv6 rules should
> not apply.
>
> root@pest:~# ip -6 tunnel add test1 mode ipip6 remote 2001:xxxx::26 local
> 2001:xxx::1:1
> root@pest:~# ip link set test1 mtu 1280
> root@pest:~# ip link set test1 mtu 1279
> RTNETLINK answers: Invalid argument
>
> This prevents the tunnel from work on paths that only support a (outer) IPv6
> MTU of 1280, since the tunnel adds an additional overhead of 40 bytes.
>
> Setting net.ipv6.conf.<if>.disable_ipv6=1 and/or removing the IPv6 link-local
> address on the tunnel interface does not help.
>
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