[bess] Re: FW: I-D Action: draft-ietf-bess-rfc7432bis-09.txt

Hi Ali,
thank you for the detailed response. Please find my follow up notes inlined
below under the GIM>> tag.

Regards,
Greg

On Wed, Jun 5, 2024 at 10:51 PM Ali Sajassi (sajassi) <sajassi@cisco.com>
wrote:

> Hi Greg,
>
>
>
> The questions that was asked initially are different that your questions.
> But let me answer them all here.
>
>
>
> The initial question was why not use the control word even when entropy
> label is used by all network nodes and my answer is that I don’t see a need
> for it and if you do, can you explain why we need the control word when
> there is no possibility of out of order delivery in the presence of ECMP
> when the network uses entropy label.
>
GIM>> I agree, if it is certain that all the PEs and Ps are capable of
handling an Entropy label and all the PEs apply it in the EVPN
encapsulation, then the use of the Control Word is optional. But I cannot
find in the draft that that is explicitly explained.

>
>
> The text in 7.11 says that the control word should be used in absence of
> entropy label.
>
GIM>> And that is not a requirement but only a recommendation concerns me.
I believe that based on draft-ietf-mpls-1stnibble
<https://datatracker.ietf.org/doc/draft-ietf-mpls-1stnibble/> it must be a
requirement.

>
>
> Regarding your suggestion of the control word must be enabled always, it
> should not and it should be per operator control. Imagine that the PE (and
> the network) can do both entropy label and control word and the operator
> wants to use entropy label, therefore, it disables the control word locally!
>
GIM>> If an implementation interprets the administrative state of Control
Word in this way, then I agree with you. But the draft doesn't tell the
reader that if the local state of Control Word is disabled, that means that
the PE node uses the Entropy label for load-balancing. Personally, I would
refer to these states as Use Control Word/Use Entropy Label.

>
>
> Regarding why using “SHOULD” instead of “MUST” because it is just a
> recommendation and the packet flow can work without it (i.e., without
> having out-of-order delivery).
>
GIM>> And that seems to contradict draft-ietf-mpls-1stnibble
<https://datatracker.ietf.org/doc/draft-ietf-mpls-1stnibble/>.

>
>
> Cheers,
>
> Ali
>
>
>
> *From: *Greg Mirsky <gregimirsky@gmail.com>
> *Date: *Wednesday, June 5, 2024 at 2:06 PM
> *To: *Ali Sajassi (sajassi) <sajassi@cisco.com>
> *Cc: *Menachem Dodge <mdodge@drivenets.com>,
> draft-ietf-bess-rfc7432bis@ietf.org <draft-ietf-bess-rfc7432bis@ietf.org>,
> bess@ietf.org <bess@ietf.org>, draft-ietf-mpls-1stnibble@ietf.org <
> draft-ietf-mpls-1stnibble@ietf.org>
> *Subject: *Re: [bess] FW: I-D Action: draft-ietf-bess-rfc7432bis-09.txt
>
> Hi Ali,
>
> thank you for your question. Section 7.11, as I understand it, states:
>
>                 It is
>
>                 recommended that the control word be included in the
>
>                 absence of an entropy label [RFC6790].
>
> If I understand correctly, the CW SHOULD be used, thus allowing for
> sending EVPN packets without the Control Word if node doesn't support the
> Entropy label. Correct?
>
> Furthermore, I have a concern regarding the local control of the Control
> Word, as described in
>
>    When the L2-Attr Extended Community is received from a remote PE, the
>
>    control word C flag MUST be checked against local control word
>
>    enablement.
>
> I believe that local policy must always enable the Control Word.
>
> Also, I have questions about rules 2 and 3 listed in Section 18 (rule 1
> is, IMHO, correct):
>
>    *  If a network uses deep packet inspection for its ECMP, then the
>
>       the following rules for "Preferred PW MPLS Control Word" [RFC4385]
>
>       apply:
>
>       -  It MUST be used with the value 0 (e.g., a 4-octet field with a
>
>          value of zero) when sending unicast EVPN-encapsulated packets
>
>          over an MP2P LSP.
>
>
>
>       -  It SHOULD NOT be used when sending EVPN-encapsulated packets
>
>          over a P2MP or P2P RSVP-TE LSP.
>
>
>
>       -  It SHOULD be used with the value 0 when sending EVPN-
>
>          encapsulated packets over a mLDP P2MP LSP.  There can be
>
>          scenarios where multiple links or tunnels can exist between two
>
>          nodes and thus it is important to ensure that all packets for a
>
>          given flows take the same link (or tunnel) between the two
>
>          nodes.
>
> Why are cases listed in these two rules not using MUST?
>
>
>
> Regards,
>
> Greg
>
>
>
> On Tue, Jun 4, 2024 at 10:00 PM Ali Sajassi (sajassi) <sajassi@cisco.com>
> wrote:
>
> Hi Greg, Menachem:
>
>
>
> I believe during the Greg’s presentation at the BESS WG (which I was
> attending remotely), I voiced my concerns regarding mandating control word
> for all cases. So, let me repeat it in context of your comment:
>
>
>
> Why do we need to mandate control word when all nodes in a network use
> entropy label for ECMP load balancing?
>
>
>
>
>
> Cheers,
>
> Ali
>
>
>
> *From: *Greg Mirsky <gregimirsky@gmail.com>
> *Date: *Thursday, May 30, 2024 at 8:20 PM
> *To: *Menachem Dodge <mdodge@drivenets.com>,
> draft-ietf-bess-rfc7432bis@ietf.org <draft-ietf-bess-rfc7432bis@ietf.org>,
> bess@ietf.org <bess@ietf.org>
> *Cc: *draft-ietf-mpls-1stnibble@ietf.org <
> draft-ietf-mpls-1stnibble@ietf.org>
> *Subject: *Re: [bess] FW: I-D Action: draft-ietf-bess-rfc7432bis-09.txt
>
> Dear All,
>
> I share Menachem's concerns and welcome feedback from the authors.
>
>
>
> Regards,
>
> Greg
>
>
>
> On Sun, May 5, 2024 at 12:33 AM Menachem Dodge <mdodge@drivenets.com>
> wrote:
>
> Hello Authors,
>
>
>
> Just wondering why none of the discussion held at Brisbane meeting in
> March and subsequently on the emailing list regarding the PFN ( see the
> emails with subject: “Re: [bess] PFN questions in rfc4732bis” )  requesting
> changes in setion 7.11.1 and section 18 , were not included in the latest
> draft update.
>
>
>
> I think the last email on this subject was sent on 15th April 2024.
>
>
>
> In section 7.11 following the discussions I think that the following sentence *should be removed*:
> “It is recommended that the control word be included in the absence of an entropy label [RFC6790].”
>
>
>
>  In section 18 “If a network (inclusive of all PE and P nodes) uses entropy labels
>
>       per [RFC6790] for ECMP load balancing, then the control word may
>
>       not be used.
>
>
>
> *Should be changed to:*  “If a network (inclusive of all PE and P nodes) uses entropy labels
>
>       per [RFC6790] for ECMP load balancing, then the control word should
>
>       be used, refer to draft-ietf-mpls-1stnibble
>
>
>
>
>
> Thank you kindly,
>
>
>
> Best Regards,
>
> Menachem Dodge
>
>
>
>
>
> *From: *BESS <bess-bounces@ietf.org> on behalf of internet-drafts@ietf.org
> <internet-drafts@ietf.org>
> *Date: *Friday, 3 May 2024 at 7:42
> *To: *i-d-announce@ietf.org <i-d-announce@ietf.org>
> *Cc: *bess@ietf.org <bess@ietf.org>
> *Subject: *[bess] I-D Action: draft-ietf-bess-rfc7432bis-09.txt
>
> CAUTION: External E-Mail - Use caution with links and attachments
>
>
> Internet-Draft draft-ietf-bess-rfc7432bis-09.txt is now available. It is a
> work item of the BGP Enabled ServiceS (BESS) WG of the IETF.
>
>    Title:   BGP MPLS-Based Ethernet VPN
>    Authors: Ali Sajassi
>             Luc Andre Burdet
>             John Drake
>             Jorge Rabadan
>    Name:    draft-ietf-bess-rfc7432bis-09.txt
>    Pages:   73
>    Dates:   2024-05-02
>
> Abstract:
>
>    This document describes procedures for Ethernet VPN (EVPN), a BGP
>    MPLS-based solution which addresses the requirements specified in the
>    corresponding RFC - "Requirements for Ethernet VPN (EVPN)".  This
>    document obsoletes RFC7432 (BGP MPLS-Based Ethernet VPN) and updates
>    RFC8214 (Virtual Private Wire Service Support in Ethernet VPN).
>
> The IETF datatracker status page for this Internet-Draft is:
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__datatracker.ietf.org_doc_draft-2Dietf-2Dbess-2Drfc7432bis_&d=DwICAg&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=cezglEhs6Oa_CKN9mhFbT8T8kmWwaNdtBDjE9bvBG_E&m=gDpQwIZuZSEOcOuIUV_9_jeGv5m-aqXgzBMzkuCM8wBeIKaKwaQUthJPFuNNZ9Dh&s=Xt33XJv3urxYTFARXBfpdw-RopowitrC7SWSv-L-QBY&e=
>
> There is also an HTMLized version available at:
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__datatracker.ietf.org_doc_html_draft-2Dietf-2Dbess-2Drfc7432bis-2D09&d=DwICAg&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=cezglEhs6Oa_CKN9mhFbT8T8kmWwaNdtBDjE9bvBG_E&m=gDpQwIZuZSEOcOuIUV_9_jeGv5m-aqXgzBMzkuCM8wBeIKaKwaQUthJPFuNNZ9Dh&s=oBT0K_2O-jJC2YfcS2X7Srom1ebB2VtVjfyN0CSBZpw&e=
>
> A diff from the previous version is available at:
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__author-2Dtools.ietf.org_iddiff-3Furl2-3Ddraft-2Dietf-2Dbess-2Drfc7432bis-2D09&d=DwICAg&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=cezglEhs6Oa_CKN9mhFbT8T8kmWwaNdtBDjE9bvBG_E&m=gDpQwIZuZSEOcOuIUV_9_jeGv5m-aqXgzBMzkuCM8wBeIKaKwaQUthJPFuNNZ9Dh&s=qjFH58VBc_cT930wv8yqvpU4plxuyfST4kkQHhRr5q4&e=
>
> Internet-Drafts are also available by rsync at:
> rsync.ietf.org::internet-drafts
>
>
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