Re: [bess] [Idr] draft-ietf-bess-evpn-overlay vs. draft-ietf-idr-tunnel-encaps

[<[e-mail]>]

Hi John,

John.
> When the tunnel encaps draft was first published it did not carry 
> forward the RFC 5512 extended community and it did not propose to 
> obsolete RFC 5512.  There was discussion of using the attribute 
> defined in the tunnel encaps draft instead of the extended community 
> and we decided to continue to use the extended community.  So, in that 
> sense we are misaligned with the tunnel encaps draft.

As you confirm below, the last sentence is only true in the past tense.

> Subsequently, however, the tunnel encaps draft decided to carry 
> forward the extended community and to obsolete RFC 5512, so we were 
> effectively covered by a grandfather clause.
>

Yes, precisely: given the content of the two drafts, there is no 
misalignment anymore.

> Given the overlay draft’s tardiness, I don’t think that’s acceptable 
> and would prefer to continue to refer to RFC 5512.
>

I do not think that the additional publication delay is a sound 
rationale for normatively refer to a spec that is known to become obsolete.
If it helps, the draft can keep an informative ref to RFC5512 and remind 
that it does not rely on anything specifically introduced by 
draft-ietf-idr-tunnel-encaps and not existing already in RFC5512.

-Thomas


2016-05-06, John E Drake:
>
> However, even though I agreed yesterday to refer to the tunnel encaps 
> draft instead of RFC 5512 we have an issue with doing this, viz, the 
> overlay draft makes a normative reference to RFC 5512.  If we change 
> the normative reference to the tunnel encaps draft we cannot publish 
> the overlay draft until after the tunnel encaps draft has been published.
>
> Given the overlay draft’s tardiness, I don’t think that’s acceptable 
> and would prefer to continue to refer to RFC 5512.
>
> Yours Irrespectively,
>
> John
>
> *From:*[e-mail] [mailto:[e-mail]]
> *Sent:* Thursday, May 05, 2016 5:47 PM
> *To:* IDR; BESS; [e-mail]; Ali 
> Sajassi (sajassi); Rabadan, Jorge (Nokia - US); 
> [e-mail]; John E Drake
> *Subject:* RE: [Idr] draft-ietf-bess-evpn-overlay vs. 
> draft-ietf-idr-tunnel-encaps
>
> Hi John,
>
> I have a hard time reconciliating the fact that yesterday you were 
> fine with having bess-evpn-overlay refer to idr-tunnel-encap instead 
> of RFC5512, with the fact that you consider (below) the two docs "not 
> aligned" for unicast.
>
> Can you be more explicit in where the "misalignment" lies?
>
> -Thomas
>
> ---- John E Drake a écrit ----
>
> Thomas,
>
> The overlay draft preceded the tunnel encaps draft and it was designed 
> to handle a very specific problem, marrying the EVPN control plane to 
> the VXLAN data plane draft and modulo the correction to section 9 it 
> is internally consistent.
>
> The tunnel encaps draft solves a more general problem and the WG 
> decided a long time ago that the overlay draft was not going to be 
> updated to use the mechanisms it details for unicast, so the overlay 
> draft is already explicitly not in alignment with it.
>
> This, plus the fact that the tunnel encaps draft explicitly puts the 
> PMSI out of scope, leads me to the conclusion that the overlay draft 
> should not be tweaked to be in alignment with a future solution for 
> encoding VNIs for multicast.
>
> Yours Irrespectively,
>
> John
>
> *From:*[e-mail] <mailto:[e-mail]> 
> [mailto:[e-mail]]
> *Sent:* Thursday, May 05, 2016 8:32 AM
> *To:* John E Drake; IDR; BESS; 
> [e-mail] 
> <mailto:[e-mail]>; Ali Sajassi 
> (sajassi); Rabadan, Jorge (Nokia - US); 
> [e-mail] 
> <mailto:[e-mail]>
> *Subject:* RE: [Idr] draft-ietf-bess-evpn-overlay vs. 
> draft-ietf-idr-tunnel-encaps
>
> Thanks for the clarification on the intent around 
> draft-ietf-bess-evpn-overlay. Then indeed section 9 needs some tidying 
> up.
>
> The issue that I think remain is that it would be much cleaner to 
> explain how to use PMSI with overlay encaps in a spec not specific to 
> E-VPN and in a way more consistent to what is done for unicast.
>
> It seems if course that draft-ietf-idr-tunnel-encap should be the 
> place, but that document currently explicitly makes PMSIs out of scope.
>
> Shouldn't this part of draft-ietf-idr-tunnel-encap be revisited ?
>
> -Thomas
>
>
> ---- Rabadan, Jorge (Nokia - US) a écrit ----
>
> Fully agree John. That's what I meant, sorry if I didn't make myself 
> clear. Section 9 needs clean up, yes.
>
> Thanks,
> Jorge
>
> _____________________________
> From: EXT John E Drake <[e-mail] <mailto:[e-mail]>>
> Sent: Wednesday, May 4, 2016 23:34
> Subject: RE: [Idr] draft-ietf-bess-evpn-overlay vs. 
> draft-ietf-idr-tunnel-encaps
> To: IDR <[e-mail] <mailto:[e-mail]>>, Ali Sajassi (sajassi) 
> <[e-mail] <mailto:[e-mail]>>, Rabadan, Jorge (Nokia 
> - US) <[e-mail] 
> <mailto:[e-mail]>>, BESS <[e-mail] 
> <mailto:[e-mail]>>, <[e-mail] 
> <mailto:[e-mail]>>, EXT - 
> [e-mail] <mailto:[e-mail]> 
> <[e-mail] <mailto:[e-mail]>>
>
>
> Jorge,
>
> We put the VNI value in the MPLS label field of the PMSI attribute for 
> all service types, and we put a value in the Ethernet Tag field 
> following the rules for each service type as described in 5.1.3 
> (https://tools.ietf.org/html/draft-ietf-bess-evpn-overlay-02#section-5.1.3).
>
> You're right that we need to clean up section 9.
>
> Yours Irrespectively,
>
> John
>
> > -----Original Message-----
> > From: Rabadan, Jorge (Nokia - US) [mailto:[e-mail]]
> > Sent: Wednesday, May 04, 2016 3:53 PM
> > To: John E Drake; EXT - [e-mail] 
> <mailto:[e-mail]>; BESS; IDR; draft-ietf-bess-evpn-
> > [e-mail] <mailto:[e-mail]>; Ali Sajassi 
> (sajassi)
> > Subject: Re: [Idr] draft-ietf-bess-evpn-overlay vs. 
> draft-ietf-idr-tunnel-encaps
> >
> > Hi John,
> >
> > About this:
> >
> > [JD] For the IMET route the MPLS label field is carried in the PMSI 
> attribute. I think we need
> > to ask everyone whether they used the Ethernet Tag or the PMSI 
> attribute to carry the VNI
> >
> >
> > In case it helps, I’ve seen a few implementations running and they 
> all encode the VNI in the
> > MPLS label field in the PTA. And a couple of them, encode the VNI in 
> the ethernet-tag, in
> > addition to the MPLS label in the PTA. In any case, I think section 
> 9 contradicts section 5.1.3
> > and should be clarified.
> >
> > "5.1.3 Constructing EVPN BGP Routes
> > <snip>
> > the MPLS label field in the MAC Advertisement, Ethernet AD per EVI, 
> and **Inclusive
> > Multicast Ethernet Tag** routes is used to carry the VNI or VSID."
> >
> > Thanks.
> > Jorge
> >
> >
> >
> >
> >
> > On 5/4/16, 8:34 PM, "EXT John E Drake" <[e-mail] 
> <mailto:[e-mail]>> wrote:
> >
> > >Thomas and Jorge,
> > >
> > >Snipped, comments inline.
> > >
> > >Yours Irrespectively,
> > >
> > >John
> > >
> > >> >
> > >> >draft-ietf-bess-evpn-overlay (see section 9) relies on the BGP
> > >> >Encapsulation extended to encode the tunnel encap to use for BUM
> > >> >traffic, but contrary to other E-VPN routes, relies on the Ethernet
> > >> >Tag field of the NLRI to encode the VNI/VSID.
> > >>
> > >> [JORGE] This is certainly a leftover from an old version where the
> > >> VNI/VSID was encoded in the ethernet tag for all the routes. The VNI
> > >> should be encoded in the Label field in all the routes. This has 
> to be corrected.
> > >>
> > >> In fact, section 5.1.3 says:
> > >>
> > >> 5.1.3 Constructing EVPN BGP Routes
> > >>
> > >> <snip>
> > >>
> > >> Accordingly, and
> > >> specifically to support the option of locally assigned VNIs, the MPLS
> > >> label field in the MAC Advertisement, Ethernet AD per EVI, and
> > >> Inclusive Multicast Ethernet Tag routes is used to carry the VNI or
> > >> VSID. For the balance of this memo, the MPLS label field will be
> > >> referred to as the VNI/VSID field. The VNI/VSID field is used for
> > >> both local and global VNIs/VSIDs, and for either case the entire 24-
> > >> bit field is used to encode the VNI/VSID value.
> > >>
> > >> <snip>
> > >
> > >
> > >[JD] For the IMET route the MPLS label field is carried in the PMSI 
> attribute. I think we
> > need to ask everyone whether they
> > >used the Ethernet Tag or the PMSI attribute to carry the VNI
> > >
> > >
> > >> >>
> > >> >> There are minor things that could be improved in
> > >> >> draft-ietf-bess-evpn-overlay wrt. consistency with
> > >> >> draft-ietf-idr-tunnel-encaps :
> > >> >>
> > >> >> * since draft-ietf-idr-tunnel-encaps will deprecate RFC5512, it
> > >> >> would be better that draft-ietf-bess-evpn-overlay refers to
> > >> >> draft-ietf-idr-tunnel-encaps and not anymore to RFC5512.
> > >>
> > >> [JORGE] I agree, as long as draft-ietf-idr-tunnel-encaps keeps the
> > >> encapsulation extended community. There are a few implementations
> > >> using this community and it is enough when only the encapsulation 
> type is needed.
> > >
> > >
> > >[JD] I agree and the tunnel encaps draft does keep the EC
> > >
> > >
> > >>
> > >> >>
> > >> >> * I think it would be better to avoid the explicit list of encap
> > >> >> types in section 5.1.3, and rather refer to
> > >> >> draft-ietf-idr-tunnel-encaps instead
> > >>
> > >> [JORGE] I agree.
> > >
> > >
> > >[JD] According to IANA, it allocated the five tunnels types to the
> > >overlay draft so I think we need to keep them
> > >
> > >
> > >>
> > >> >> * the following minor modification was proposed, but not yet 
> incorporated:
> > >> >>
> > >> >> John Drake, 2015-11-13 (to BESS ML):
> > >> >>> For the overlay draft, replace this text in section 5.1.3:
> > >> >>>
> > >> >>> "If the BGP Encapsulation extended community is not present,
> > >> >>> then the default MPLS encapsulation or a statically configured
> > >> >>> encapsulation is assumed."
> > >> >>>
> > >> >>> With the following:
> > >> >>>
> > >> >>> "Note that the MPLS encapsulation tunnel type is needed in
> > >> >>> order to distinguish between an advertising node that only
> > >> >>> supports non-MPLS encapsulations and one that supports MPLS and
> > >> >>> non-MPLS encapsulations. An advertising node that only supports
> > >> >>> MPLS encapsulation does not need to advertise any encapsulation
> > >> >>> tunnel types; i.e., if the BGP Encapsulation extended community
> > >> >>> is not present, then either MPLS encapsulation or a statically
> > >> >>> configured encapsulation is assumed."
> > >> >>
> > >> >> I think this change is useful and should be incorporated, although
> > >> >> skipping the last sentence would be wise if the full list of
> > >> >> tunnel types is removed.
> > >
> > >
> > >[JD] Fine with me either w/ or w/o the last sentence
> > >
> > >
>


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