Re: [spring] Typo correction Re: Question from SPRING regarding draft-filsfilscheng-spring-srv6-srh-compression

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

Joel,
On 13-Oct-21 20:37, Joel M. Halpern wrote:

<snip>

>> 1) Does the placement of a list of sids in the IPv6 DA field change the 
>> IPv6 architectural description of that field.


That's why I recently asked for a set of examples of the resulting
"addresses". I don't understand enough of SRV6 to understand what
the bit patterns in such addresses will actually be. And I don't care
about the details of SRV6, given that it will only be used in certain
special types of network. So I can only answer your question based
on concrete examples. Are they compatible with RFC4291 or not?

(There's a subsidiary question which IMHO is in some ways more important
than the architectural question: what existing code and devices will such
addresses break?)

>> 2) Does the operation of shifting information around in the IPv6 
>> destination address field represent a modification or extension of the 
>> IPv6 data plane.


Including semantics *of any kind* in an IP address is a very fundamental
change to the concept of IP. I may be wrong, but I'm not aware that any
RFCs prior to SRV6 have done this, and the founding reference for what 
an address *is* still seems to be IEN19 [1].

So I'm not concerned that srv6-srh-compression has any more fundamental
impact than basic SRV6 or RFC8986. (However, this aspect of SRV6 was
one of my primary motivations for RFC8799. What happens in SRV6 stays
in SRV6.)

[1] https://www.rfc-editor.org/ien/ien19.txt)

<more snip>

Regards
   Brian