Subject: Re: [Last-Call] Last Call: <draft-ietf-opsawg-vpn-common-09.txt> (A Layer 2/3 VPN Common YANG Model) to Proposed Standard

From: <[email-masked]>
Date: Mon, 6 Sep 2021 07:37:22 +0000

Hi Tom, all, 

The address family is simply referring to the VPN connectivity type, this is not to be mixed with AFIs/SAFIs. For routing data nodes, it indicates whether a given protocol is used to provide connectivity for IPv4, IPv6, or both. The setting of which routing protocol version, whether one single or multiple instances, etc. is deployment-specific.

The actual AFIs/SAFIs (e.g., l3vpn-ipv4-unicast (AFI,SAFI = 1,128)) will be derived when translating the network model into device-specific configuration.

Cheers,
Med

> -----Message d'origine-----
> De : tom petch [mailto:[email-masked]]
> Envoyé : lundi 2 août 2021 18:09
> À : [email-masked]
> Cc : [email-masked]; [email-masked];
> [email-masked]
> Objet : Re: Last Call: <draft-ietf-opsawg-vpn-common-09.txt> (A
> Layer 2/3 VPN Common YANG Model) to Proposed Standard
> 
> On 16/07/2021 17:06, The IESG wrote:
> >
> > The IESG has received a request from the Operations and Management
> > Area Working Group WG (opsawg) to consider the following document:
> -
> > 'A Layer 2/3 VPN Common YANG Model'
> >    <draft-ietf-opsawg-vpn-common-09.txt> as Proposed Standard
> 
> This I-D creates an additional set of YANG identity for address-
> family with semantics I have not seen before and which seem
> inappropriate for routing protocols.
> 
> 'address family' has long been a concept in BGP and there is an
> IANA-maintained registry most of which is unlikely to be seen in
> practice (e.g. Decnet IV, Banyan Vines) and so does not provide a
> good basis for YANG modules.
> 
> RFC8349 (routing) defines a separate set of identity more suitable
> for current protocols, of IPv4 unicast, IPv6 unicast, with the
> expectation that others would be added, such as mpls, which indeed
> has happened (RFC8960).
> 
> This I-D goes in a different direction, defining ipv4, ipv6 and dual
> stack.  This last is a term that seems alien to routing, rather
> something for host implementations concerned with migrating from
> ipv4 to ipv6.  Further, the way the identity is used, as in draft-
> ietf-opsawg-l3sm-l3nm, is that ipv4 means ipv4 and not ipv6, and
> vice versa, so that YANG tests that are simple in other modules e.g.
> for
> ipv4 alone or in combination with others become complex having to
> test for 'dual stack but not ipv6' or dual stack as well as ipv4.
> 
> But it is when dual stack is applied to OSPF that I lose the plot.
> OSPF has v2 and v3 and that is how every other YANG module models it
> AFAIK, base identity ospf with derivations of ospfv2 and ospfv3,
> allowing simple tests for one or other or both, depending on what
> function is being tested for.  As used in draft-ietf-opsawg-l3sm-
> l3nm, I see ospf and ipv4, ospf and ipv6, ospf and dual stack; this
> last makes no sense to me.  ospfv3 is happy to convey ipv4 and ipv6
> information so what is it then, what if it only conveys ipv4?
> 
> dual stack as a concept should be limited to applications, not
> routing.
>   It may make sense for the applications, the services that a vpn
> supports, as modelled in draft-ietf-opsawg-lsm-lnm, but I can make
> no sense of its application to protocols such as OSPF and BGP (or
> any other routing protocol).
> 
> Tom Petch
> 
> >
> > The IESG plans to make a decision in the next few weeks, and
> solicits
> > final comments on this action. Please send substantive comments to
> the
> > [email-masked] mailing lists by 2021-08-06. Exceptionally,
> > comments may be sent to [email-masked] instead. In either case,
> please
> > retain the beginning of the Subject line to allow automated
> sorting.
> >
> > Abstract
> >
> >
> >     This document defines a common YANG module that is meant to be
> reused
> >     by various VPN-related modules such as Layer 3 VPN and Layer 2
> VPN
> >     network models.
> >
> > Editorial Note (To be removed by RFC Editor)
> >
> >     Please update these statements within the document with the
> RFC
> >     number to be assigned to this document:
> >
> >     o  "This version of this YANG module is part of RFC XXXX;"
> >
> >     o  "RFC XXXX: A Layer 2/3 VPN Common YANG Model";
> >
> >     o  reference: RFC XXXX
> >
> >     Also, please update the "revision" date of the YANG module.
> >
> >
> >
> >
> > The file can be obtained via
> > https://datatracker.ietf.org/doc/draft-ietf-opsawg-vpn-common/
> >
> >
> >
> > No IPR declarations have been submitted directly on this I-D.
> >
> >
> >
> >
> >
> > _______________________________________________
> > IETF-Announce mailing list
> > [email-masked]
> > https://www.ietf.org/mailman/listinfo/ietf-announce
> > .
> >

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