Hi, Guanghui,

Le 2012-03-23 à 04:04, Guanghui Yu a écrit :

> Hi Yiu
> 
>    4rd-u changes the IPv6 header architecture (redefine fragmentation header 
> extension)

4rd-U uses between CEs and BRs an IPv6 packet format that not only is 
completely authorized, but that is already 
used in double translation: RFC6145 also adds a fragmentation header to some 
unfragmented packets (sec 4.).


> and IPv6 address architecture (different meaning of u-bit when g-bit=1).

- U builds on the fact that all IPv6 unicast addresses are so far either 
universal scope (u=1 g=0) or local link scope (u=0 g=any value). This 
(fortunately) leaves an escape combination for new types of addresses (U is 
only one of these possible addresses, but the first one).
- A 4rd-U address happens to be partially universal scope (embedded public IPv4 
addresses) and partially ISP-domain scope (dependent on ISP defined mapping 
rules). None of the existing formats is therefore mandatorily applicable.
- Impact on IPv6 address architecture is only a backward compatible extension: 
no interference is possible with anything that works in conformance with 
current IPv6 specifications.


> These are the fundamental changes. If 4rd-u becomes the standard, then there 
> will be new defined “IPv6” packets on the Internet, which are not compatible 
> with existing IPv6 packets and

Please see above.

> no existing devices can understand those packets.

Only BRs and CEs need to understand that these packets have IPv4 compatible 
payloads.


Regards,
RD

>    
> 
> Yu Guanghui <ygh at dlut.edu.cn>
> Network and Information Center
> Dalian University of Technology, China
> 
> 
> On Fri, Mar 23, 2012 at 10:10 AM, Lee, Yiu <[email protected]> wrote:
> Hi Guanghui,
> 
> I agree that both MAP and 4rd-u are similar technology and solving the same 
> problem. From technical perspective, can you elaborate this a lithe bit? 
> 
> Thanks,
> Yiu
> 
> From: Guanghui Yu <[email protected]>
> Date: Thu, 22 Mar 2012 20:26:40 +0800
> To: Softwires WG <[email protected]>
> Subject: Re: [Softwires] Path to move forward with 4rd…
> 
> I read 4rd-u draft and found it is flawed.
> 
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