Re: [spring] Question about IPv6 EH-insertion in draft-ietf-spring-srv6-network-programming

[Fernando Gont <[e-mail]>]

On 7/9/19 14:43, Robert Raszuk wrote:
> 
>     So, double-checking if I understood correctly: You are saying that the
>     two uses cases that you are referring to already have an alternative
>     specification with encap/decap, but this document proposes to use EH
>     insertion to avoid the extra overhead of adding an additional IPv6
>     header?
> 
> 
> That is correct. 
> 
> I have been telling you this over and over again and you were choosing
> not to accept it. 

Then you have answered my previous question. This EH-insertion thing is
not solving any problem that cannot be solved with the standard that we
have, and instead introduces potential problems.

You shouldn't be surprised if, modulo social engineering, the proposal
for EH insertion doesn't fly in 6man.

That said, I think EH insertion should be removed from this document, on
the basis that:

* It breaks an existing standard (RFC8200) that explicitly banned it for
technical concerns.

* It doesn't solve a problem that cannot be solved with encap/decap, and
in fact introduces potential problems.




> So per your and few other comments he would not be able to add another
> local (to the protection zone) SRH to his already encapsulated on
> ingress packet, but would have to add another IPv6 encapsulation with
> SRH to be in line with RFC8200 even if the only point of the new SRH is
> local single dst detour and protection of arriving dst address in the
> outer  most IPv6 header. 
> 
> How efficient/wise that is ? 

That's certainly, at least, a cleaner design than inserting EHs in the
network (and there's no such a thing as a free lunch). Inserting EHs is,
if anything, a hack.

As a side comment, if you have concerns wasted bits (and since you
stress all the time that SR operates in a "limited domain") a quick
comment would be: why do you use IPv6 addresses (IDs of global scope) to
identify the SR nodes?

Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: [e-mail]
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