Re: [v6ops] draft-ietf-v6ops-ula-usage-recommendations - work or abandon?

[Nick Hilliard <[e-mail]>]

On 08/11/2015 05:25, Lorenzo Colitti wrote:
> On Fri, Nov 6, 2015 at 7:08 PM, Nick Hilliard <[e-mail]> wrote:
>>    On 06/11/2015 00:20, Lorenzo Colitti wrote:
>>>     It breaks any application that requires that the application know its
>>>     source address. Examples are SIP, FTP, audio/video chat, etc.
>     your argument is the wrong way around: some protocols deliberately
>     introduce layering violations by demanding that transport identifier
>     information is encoded at the application layer.  Transport identifier
>     translation merely shows up this brokenness.  The brokenness is not
>     with the translation mechanism but with the higher level protocols.
> 
> Nope. Those protocols aren't broken, they worked fine for years until NAT
> arrived and broke them. They still work fine on networks that operate the
> way the Internet was originally designed with end-to-end connectivity.

NAT predates both sip and the vast majority of other protocols which encode
inline transport layer identifiers (skype, other chat, etc).

Also, I hope you're not arguing that protocol layering violations are
acceptable from a design point of view.

You're correct that ftp predates nat but having said that, its layering
violations were recognised from the earliest days of the internet as being
atrocious protocol design because of the problems they caused.

Nick