I have reread the draft. let me try asking the quesiton the opposite way.
1) If the argument length is zero, then an Ingress PE will always ignore
the SRv6 Endpoint behavior, as it will not do anything differently if it
understands or does not understand the behavior.
2) If the argument length is non-zero, but it is being filled in by the
transportion mechanism, then again the Ingress PE might as well ignore
the SRv6 Endpoint Behavior Information
3) If other information such as the use of the MPLS ESI or label (EVPN
Auto-Discovery) is used to fill in the argument, this is determined from
the type information and not from the SRv6 Endpoint Behavior?
4) If none of those cases apply, and the SRv6 Endpoint Behavior is known
by the Ingress PE, and that behavior reuries other manipulation of the
argument field of the resulting SID, then the Ingress PE acts on that
information? And the advertiser has to somehow ensure that all
receivers will correctly understand the necessary manipulation?
It seems that carrying the SRv6 Endpoint Behavior, and trying to
describe when it needs to be understood, is for a use case that is not
even covered in the document?
Yours,
Joel
On 3/20/2022 2:54 AM, Ketan Talaulikar wrote:
Hi Joel,
Please see inline below.
On Sun, Mar 20, 2022 at 11:34 AM Joel M. Halpern <[email protected]
<mailto:[email protected]>> wrote:
I seem to be missing something.
The ingress PE (domain edge) applies the destination SID (possibly as
part of a SID list). Either it is deciding to use the destination SID,
or something else is deciding to use the destination SID.
KT> The ingress PE is deciding. Something else (e.g., a controller) may
decide the path (e.g., SID list for SR Policy) but the Service/VPN
context is signaled via BGP from egress to ingress PE.
Ignoring the issue of argument manipulation, if the Ingress PE is
deciding on its own, doesn't it have to understand the meaning of the
behavior in order to decide that it wants to invoke it?
KT> The ingress PE is not invoking anything and hence it doesn't need to
understand the meaning of the behavior (with some exceptions like when
it needs to supply the argument). Ingress PE is simply setting the
received SRv6 Service SID as the IPv6 DA in the outer encapsulation
(let's keep aside SR Policy for now). When this packet reaches the
egress PE, it ends up invoking the behavior corresponding to the locally
instantiated SRv6 SID on the egress PE. As an analogy - whether the
label signaled by the egres PE is per-VRF or per-CE does not affect the
processing at ingress PE.
If something else provides the SID list and the rules for which traffic
should use it (e.g. the SR policy or similar) then the Ingress PE would
not seem to need such understanding.
KT> The situation is the same even in this case.
Thanks,
Ketan
Yours,
Joel
On 3/20/2022 1:37 AM, Ketan Talaulikar wrote:
> Hi Joel,
>
> There is no implicit assumption such as the one you refer to. The
> ingress PE does not need to do anything specific with the choice
of the
> behavior picked by the egress PE except where the behavior
involves the
> use of argument. Ingress PE does need to know & support the specific
> behavior when it needs to supply the argument based on the behavior
> definition.
>
> Thanks,
> Ketan
>
> On Sun, Mar 20, 2022 at 10:56 AM Joel M. Halpern
<[email protected] <mailto:[email protected]>
> <mailto:[email protected] <mailto:[email protected]>>> wrote:
>
> I keep reading the description of the handling of unknown
endpoint
> behaviors.
>
> It seems there is an implicit assumption that I would think
it would be
> helpful to make explicit. As far as I can tell, a head end
would never
> choose based purely based on local policy to make use of an
advertised
> SID with an unknown behavior? However, a head end might use
such a
> ISD,
> without knowing what it was really asking, if so instructed
by a policy
> engine (e.g. SR Policy)?
>
> Yours,
> Joel
>
> On 3/19/2022 11:32 PM, [email protected]
<mailto:[email protected]>
> <mailto:[email protected]
<mailto:[email protected]>> wrote:
> >
> > A New Internet-Draft is available from the on-line
> Internet-Drafts directories.
> > This draft is a work item of the BGP Enabled ServiceS WG
of the IETF.
> >
> > Title : SRv6 BGP based Overlay Services
> > Authors : Gaurav Dawra
> > Clarence Filsfils
> > Ketan Talaulikar
> > Robert Raszuk
> > Bruno Decraene
> > Shunwan Zhuang
> > Jorge Rabadan
> > Filename : draft-ietf-bess-srv6-services-13.txt
> > Pages : 34
> > Date : 2022-03-19
> >
> > Abstract:
> > This document defines procedures and messages for
SRv6-based BGP
> > services including L3VPN, EVPN, and Internet services. It
> builds on
> > RFC4364 "BGP/MPLS IP Virtual Private Networks (VPNs)"
and RFC7432
> > "BGP MPLS-Based Ethernet VPN".
> >
> >
> > The IETF datatracker status page for this draft is:
> >
https://datatracker.ietf.org/doc/draft-ietf-bess-srv6-services/
<https://datatracker.ietf.org/doc/draft-ietf-bess-srv6-services/>
>
<https://datatracker.ietf.org/doc/draft-ietf-bess-srv6-services/
<https://datatracker.ietf.org/doc/draft-ietf-bess-srv6-services/>>
> >
> > There is also an htmlized version available at:
> >
>
https://datatracker.ietf.org/doc/html/draft-ietf-bess-srv6-services-13
<https://datatracker.ietf.org/doc/html/draft-ietf-bess-srv6-services-13>
>
<https://datatracker.ietf.org/doc/html/draft-ietf-bess-srv6-services-13 <https://datatracker.ietf.org/doc/html/draft-ietf-bess-srv6-services-13>>
> >
> > A diff from the previous version is available at:
> >
>
https://www.ietf.org/rfcdiff?url2=draft-ietf-bess-srv6-services-13
<https://www.ietf.org/rfcdiff?url2=draft-ietf-bess-srv6-services-13>
>
<https://www.ietf.org/rfcdiff?url2=draft-ietf-bess-srv6-services-13 <https://www.ietf.org/rfcdiff?url2=draft-ietf-bess-srv6-services-13>>
> >
> >
> > Internet-Drafts are also available by rsync at
> rsync.ietf.org::internet-drafts
> >
> >
> > _______________________________________________
> > I-D-Announce mailing list
> > [email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>
> > https://www.ietf.org/mailman/listinfo/i-d-announce
<https://www.ietf.org/mailman/listinfo/i-d-announce>
> <https://www.ietf.org/mailman/listinfo/i-d-announce
<https://www.ietf.org/mailman/listinfo/i-d-announce>>
> > Internet-Draft directories:
http://www.ietf.org/shadow.html <http://www.ietf.org/shadow.html>
> <http://www.ietf.org/shadow.html
<http://www.ietf.org/shadow.html>>
> > or ftp://ftp.ietf.org/ietf/1shadow-sites.txt
<ftp://ftp.ietf.org/ietf/1shadow-sites.txt>
> <ftp://ftp.ietf.org/ietf/1shadow-sites.txt
<ftp://ftp.ietf.org/ietf/1shadow-sites.txt>>
>
> _______________________________________________
> BESS mailing list
> [email protected] <mailto:[email protected]> <mailto:[email protected]
<mailto:[email protected]>>
> https://www.ietf.org/mailman/listinfo/bess
<https://www.ietf.org/mailman/listinfo/bess>
> <https://www.ietf.org/mailman/listinfo/bess
<https://www.ietf.org/mailman/listinfo/bess>>
>
_______________________________________________
BESS mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/bess
