Re: [Softwires] 4rd-U complement - e2e transparency to IPv4 TOS

[Satoru Matsushima <[e-mail]>]

Hi Remi-san,

> With this added, I believe that 4rd-U is a real progress over previously proposed Double translation and Encapsulation.
> It can make IMHO a valuable unified standard.

Not enough. The original TTL value in IPv4 header must be carried.

cheers,
--satoru


On 2011/10/17, at 21:36, Rémi Després wrote:

> Hi Satoru-san,
> 
> Thank you for identifying a limitation of the 4rd-U  
> You are right, as currently specified, "it doesn't support diff-serv tunneling model, pipe and short-pipe".
> All these need e2e transparency to the IPv4 Type of Service.
> 
> Fortunately, this is easy to fix: in the Identification field of the IPv6 Fragment header, copy not only the DF bits but also the IPv4 TOS.
> 
> The proposed 4r-U packet format becomes:
> 
> 
>   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>   |Vers=6 |   TrafClass   |            Flow Label                 |
>   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>   |         Payload Length        |Next Header=44 |   Hop Limit   |
>   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>   |                                                               |
>   +                                                               +
>   |                                                               |
>   +                  IPv6 Source Address                          +
>   |                                                               |
>   +                                                               +
>   |                                                               |
>   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>   |                                                               |
>   +                                                               +
>   |                                                               |
>   +                IPv6 Destination Address                       +
>   |                                                               |
>   +                                                               +
>   |                                                               |
>   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>   |  Next Header  |    Reserved   | IPv6  Fragment Offset   | 0 |M|
>   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>   |D|      0      |    IPv4 TOS   |       IPv4 Identification     |
>   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
>   |                        IPv4 Payload                           |
>   |                                                               | 
> 
> With this added, I believe that 4rd-U is a real progress over previously proposed Double translation and Encapsulation.
> It can make IMHO a valuable unified standard.
> 
> Yet, I may have missed something else. 
> New justified objections are therefore most welcome..
> 
> 
> Regards,
> RD