Re: END SID Without SRH

[David Farmer <[e-mail]>]

On Wed, Jun 12, 2019 at 9:26 PM Bob Hinden <[e-mail]> wrote:

> Darren,
>
> > On Jun 12, 2019, at 5:57 PM, Darren Dukes (ddukes) <[e-mail]>
> wrote:
> >
> > Hi Bob. See inline.
> >
> > On Jun 13, 2019, at 1:04 AM, Bob Hinden <[e-mail]> wrote:
> >
> >> Darren,
> >>
> >>> On Jun 12, 2019, at 2:52 PM, Darren Dukes (ddukes) <[e-mail]>
> wrote:
> >>>
> >>> Hello everyone.
> >>>
> >>> This document defines an SRH and a SID, and how that SID is processed.
> >>>
> >>> I expect anyone "surprised" by this fact should have read this draft
> at some point:
> >>> a - within the past 2 years; since this document has defined a SID and
> its processing.
> >>> b - within the past 13 months; since section 4.3.1 specifically
> described discarding the packet based on upper layer header being processed.
> >>> c - within the past 8 months; since the current version of 4.3.1.2 was
> updated with the new ICMP error code, published, and the WG was notified
> via email.
> >>>
> >>> And recall section 3.1 defines a Source SR node as
> >>>  "any node that originates an IPv6 packet with a
> >>>  segment (i.e.  SRv6 SID) in the destination address of the IPv6
> >>>  header.  The packet leaving the source SR Node may or may not contain
> >>>  an SRH."
> >>>
> >>> In other words, there is no surprise.
> >>
> >> I am trying to sort out this discussion.
> >>
> >> I think the text in the draft this discussion is about is:
> >>
> >>> 4.3.1.2.  Upper-layer Header or No Next Header
> >>>
> >>>   When processing the Upper-layer header of a packet matching a FIB
> >>>   entry locally instantiated as an SRv6 SID defined in this document.
> >>>
> >>>   IF (Upper-layer Header is IPv4 or IPv6) and
> >>>       local configuration permits {
> >>>     Perform IPv6 decapsulation
> >>>     Resubmit the decapsulated packet to the IPv4 or IPv6 module
> >>>   }
> >>>   ELSE {
> >>>     Send an ICMP parameter problem message to the Source Address and
> >>>     discard the packet.  Error code (TBD by IANA) "SR Upper-layer
> >>>     Header Error", pointer set to the offset of the upper-layer
> >>>     header.
> >>>   }
> >>>
> >>>   A unique error code allows an SR Source node to recognize an error in
> >>>   SID processing at an endpoint.
> >>
> >>
> >> If I understand it correctly, the case for the action described in this
> section  is:
> >>
> >>   When processing the Upper-layer header of a packet matching a FIB
> >>   entry locally instantiated as an SRv6 SID defined in this document.
> >>
> >> A node receiving this packet that knows it is SRv6 SID (because it was
> locally instantiated), would follow this procedure.
> >
> > Correct.
> >
> >> A node who does not know that it is an SRv6 SID, will process the
> packet normally as defined in RFC8200/etc/etc.
> >>
> >
> > Yes. This case is covered by section by 4.3.3 specifically, where the
> destination lpm matches a non-local Route.
> >
> >
> > 4.3.3. FIB Entry Is A Non-Local Route
> >
> > Processing is not changed by this document.
> >
> >> Essentially, a node will only do this if it is in an SRv6 domain
> because it has had SRv6 SID information configured manually or via some
> protocol.
> >>
> >> Am I correct?
> >
> > Yes you are correct.
> >
>
> Thanks.   I don’t see any issue here, the document is appropriately scoped.
>

It might be nice if there was a clear simple statement someplace to the
effect, "IPv6 addresses that are used for SIDs SHOULD NOT also be used and
a regular IPv6 destination."

Thanks
-- 
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