Re: [PATCH] ip6_tunnel: Correct tos value in collect_md mode

From	严海双 <yanhaishuang@cmss.chinamobile.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] ip6_tunnel: Correct tos value in collect_md mode
Date	2017-06-15 03:00 +0200
Message-ID	<tSriG-3Uo-5@gated-at.bofh.it> (permalink)
References	<tS6xz-7Me-3@gated-at.bofh.it> <tS6Hf-7QQ-1@gated-at.bofh.it> <tS92q-11P-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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> On 14 Jun 2017, at 1:28 PM, Peter Dawson <petedaws@gmail.com> wrote:
> 
> On Wed, 14 Jun 2017 10:54:31 +0800
> 严海双 <yanhaishuang@cmss.chinamobile.com> wrote:
> 
> 
>>> Changes since v2:
>>> * mask key->tos with RT_TOS() suggested by Daniel
> 
> Can you help me understand the rationale for this change? Is there are bug introduced by dsfield = ip6_tclass(key->label); ?
> 
> The RT_TOS masks out 4bits of the 8bit tos field in accordance with RFC1349 (obsoleted by RFC2474). IPv6 does not have a TOS field. So it dosen't make sense to apply a TOS value to the outer header of an IPv6 tunnel.
> 
> 

Hi, Peter

Here the tos also means Traffic Class in IPv6, see the define in struct ip_tunnel_key:

u8          tos;        /* TOS for IPv4, TC for IPv6 */

RT_TOS mask is suggested by Daniel, please refer to the implement in vxlan or geneve code:

fl6.flowlabel = ip6_make_flowinfo(RT_TOS(tos), label);

Thanks.

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[PATCH] ip6_tunnel: Correct tos value in collect_md mode Haishuang Yan <yanhaishuang@cmss.chinamobile.com> - 2017-06-14 04:50 +0200
  Re: [PATCH] ip6_tunnel: Correct tos value in collect_md mode 严海双 <yanhaishuang@cmss.chinamobile.com> - 2017-06-14 05:00 +0200
    Re: [PATCH] ip6_tunnel: Correct tos value in collect_md mode Peter Dawson <petedaws@gmail.com> - 2017-06-14 07:30 +0200
      Re: [PATCH] ip6_tunnel: Correct tos value in collect_md mode 严海双 <yanhaishuang@cmss.chinamobile.com> - 2017-06-15 03:00 +0200

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