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

[Brian E Carpenter <[e-mail]>]

On 2011-10-18 01:36, 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.

Will this cause any difficulties for ECN, if ECN is supported on the IPv6
leg of the journey?

Apart from that, please remember that the DSCP part of the DS Field is not an
end-to-end field; it is mutable. I advise applying the relevant considerations
from Sections 4.1 and 5.1 of RFC 6145.

Regards
   Brian Carpenter