Re: [PATCH net-next] ip6_gre: Fix MTU setting

Tom Herbert
2016-05-09T22:49:23Z

On Mon, May 9, 2016 at 3:44 PM, Alexander Duyck
<alexander.duyck@gmail.com> wrote:
> On Mon, May 9, 2016 at 3:28 PM, Tom Herbert <tom@herbertland.com> wrote:
>> In ip6gre_tnl_link_config set t->tun_len and t->hlen correctly for the
>> configuration. For hard_header_len and mtu calculation include
>> IPv6 header and encapsulation overhead.
>>
>> In ip6gre_tunnel_init_common set t->tun_len and t->hlen correctly for
>> the configuration. Revert to setting hard_header_len instead of
>> needed_headroom.
>>
>> Tested:
>>
>> ./ip link add name tun8 type ip6gretap remote \
>> 2401:db00:20:911a:face:0:27:0 local \
>> 2401:db00:20:911a:face:0:25:0 ttl 225
>>
>> Gives MTU of 1434. That is equal to 1500 - 40 - 14 - 4 - 8.
>>
>> ./ip link add name tun8 type ip6gretap remote \
>> 2401:db00:20:911a:face:0:27:0 local \
>> 2401:db00:20:911a:face:0:25:0 ttl 225 okey 123
>>
>> Gives MTU of 1430. That is equal to 1500 - 40 - 14 - 4 - 8 - 4.
>>
>> Signed-off-by: Tom Herbert <tom@herbertland.com>
>
> So this gives me the correct result now. However we still need patch
> 3 / 11 from the set you submitted next week in order to be able to
> even transmit because the flags are otherwise mangled.
>
> Tested-by: Alexander Duyck <aduyck@mirantis.com>

Okay, I'll repost the flags patch as a standalone. Do you have any
other issues then in this path?

Tom