Re: [v6ops] Thoughts about wider operational input

[Joe Maimon <[e-mail]>]

Simon wrote:

> Identifying endpoints in a consistent fashion is trivially easy - you use its IP address*.

Which you know because you have successful communications with it.

What you dont know is what IP address YOU have from the point of view of 
the other endpoint. And the assumption that you do requires that the 
network not change it in any way.

Which if you consider it carefully, there never was any such guarantee. 
It was just the path of least resistance.


>   It is only if the network starts mangling the address that it becomes non-trivial. “The internet” has never been "free to translate packets addressing between them for whatever reasons they want” for the simple reason that doing so breaks stuff.

But you are free to break stuff. So the network was always free to do so 
and building on the assumption that it never would turns out have been 
not the flawless design otherwise thought.

> As far as I can see, you're taking a starting point that it’s OK for “the network” to mangle packets (specifically addresses), and then using that to justify everything else. You’ve cited an RFC to support your viewpoint, but my reading of that RFC says “don’t mangle packets because it breaks things”.

Did the network every come with an explicit guarantee that the source 
address of a packet would not get changed once it left the host?

Or was that just an implicit assumption? Citation please.
>
>
> * Yes, the IP address you use needs to remain stable for the duration of the session.
>
>
> So, serious question. How do you read the RFC you cited and come to the conclusion that “the internet” has always been free to mangle addresses in any way it likes” ?
>
> Simon
>
>

I read the RFC and I see that it says if you are going to use endpoints 
identifiers you need to ensure they are consistent. And if they belong 
to other protocol layers and traverse a network you do not control, more 
than an assumption is required for that sort of reliable behavior.

Joe