Re: Fwd: New Version Notification for draft-voyer-6man-extension-header-insertion-07.txt

On Sat, Sep 21, 2019 at 10:02 AM Voyer, Daniel <daniel.voyer@bell.ca> wrote:
>
> Hi Joel,
>
> Sent from my mobile
>
> > On Sep 21, 2019, at 00:54, Joel M. Halpern <jmh@joelhalpern.com> wrote:
> >
> > I see where the draft defines a set of constraints.
> > The constraint that there be no other extension headers is a fairly drastic constraint, which would seem a cause for concern.
> >
> > Putting that aside however, the draft does not seem to provide any explanation for why insertion rather than additional encapsulation is used.  Particularly given the assumption that the MTU is large enough, it seems the encapsulation could be used for all insertion cases.
> >
> DV: correct, you can use encapsulations but at the cost of 40bytes overhead. Running an operators backbone, with a widespread among of use cases, you need those bytes..

Daniel,

The overhead difference is more like 24 bytes since the destination IP
address would need to be in the SID list in insertion case. The source
address in encapsulation is useful to provide proper attribution. In
any case, the argument that overhead matters would be much more
convincing if the segment routing header itself was sparing in
overhead (carrying a list of 16 byte IPv6 addresses is a lot of
overhead).

Tom

>
> > Yours,
> > Joel
> Regards
> Dan
> >
> >> On 9/21/2019 12:34 AM, Darren Dukes (ddukes) wrote:
> >> Hello everyone, we’ve just submitted an updated draft that explains why SRH insertion is performed in an SR domain, how it is accomplished and why it is safe within the SR domain.
> >> The authors look forward to your comments and suggestions on how to improve this document.
> >> Thanks!
> >>   Darren (on behalf of the authors)
> >>> Begin forwarded message:
> >>>
> >>> *From: *<internet-drafts@ietf.org <mailto:internet-drafts@ietf.org>>
> >>> *Subject: **New Version Notification for draft-voyer-6man-extension-header-insertion-07.txt*
> >>> *Date: *September 21, 2019 at 12:20:13 AM EDT
> >>>
> >>>
> >>> A new version of I-D, draft-voyer-6man-extension-header-insertion-07.txt
> >>> has been successfully submitted by Darren Dukes and posted to the
> >>> IETF repository.
> >>>
> >>> Name:draft-voyer-6man-extension-header-insertion
> >>> Revision:07
> >>> Title:Insertion of IPv6 Segment Routing Headers in a Controlled Domain
> >>> Document date:2019-09-20
> >>> Group:Individual Submission
> >>> Pages:13
> >>> URL: https://www.ietf.org/internet-drafts/draft-voyer-6man-extension-header-insertion-07.txt
> >>> Status: https://datatracker.ietf.org/doc/draft-voyer-6man-extension-header-insertion/
> >>> Htmlized: https://tools.ietf.org/html/draft-voyer-6man-extension-header-insertion-07
> >>> Htmlized: https://datatracker.ietf.org/doc/html/draft-voyer-6man-extension-header-insertion
> >>> Diff: https://www.ietf.org/rfcdiff?url2=draft-voyer-6man-extension-header-insertion-07
> >>>
> >>> Abstract:
> >>>   Traffic traversing an SR domain is encapsulated in an outer IPv6
> >>>   header for its journey through the SR domain.
> >>>
> >>>   To implement transport services strictly within the SR domain, the SR
> >>>   domain may require insertion or removal of an SRH after the outer
> >>>   IPv6 header of the SR domain.  Any segment within the SRH is strictly
> >>>   contained within the SR domain.
> >>>
> >>>   The SR domain always preserves the end-to-end integrity of traffic
> >>>   traversing it.  No extension header is manipulated, inserted or
> >>>   removed from an inner transported packet.  The packet leaving the SR
> >>>   domain is exactly the same (except for the hop-limit update) as the
> >>>   packet entering the SR domain.
> >>>
> >>>   The SR domain is designed with link MTU sufficiently greater than the
> >>>   MTU at the ingress edge of the SR domain.
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> Please note that it may take a couple of minutes from the time of submission
> >>> until the htmlized version and diff are available at tools.ietf.org <http://tools.ietf.org>.
> >>>
> >>> The IETF Secretariat
> >>>
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