Subject: Re: [bess] Éric Vyncke's No Objection on draft-ietf-bess-evpn-inter-subnet-forwarding-09: (with COMMENT)

From: "Eric Vyncke (evyncke)" <[email-masked]>
Date: Tue, 1 Sep 2020 08:46:19 +0000

Thank you Ali for your reply.

My comments are non-blocking anyway but I am still not too happy with your reply to
- section 2, I still find the text not really clear
- unsure whether I understand the reasoning on section 4.1

Else, happy with all your changes => they will improve the document

Regards

-éric

-----Original Message-----
From: "Ali Sajassi (sajassi)" <[email-masked]>
Date: Tuesday, 1 September 2020 at 00:25
To: Eric Vyncke <[email-masked]>, The IESG <[email-masked]>
Cc: "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>, Zhaohui Zhang <[email-masked]>
Subject: Re: Éric Vyncke's No Objection on draft-ietf-bess-evpn-inter-subnet-forwarding-09: (with COMMENT)

    Hi Eric,

    Thanks for your review and your comments, please refer to my replies inline marked with [AS].

    On 7/14/20, 5:32 AM, "Éric Vyncke via Datatracker" <[email-masked]> wrote:

        Éric Vyncke has entered the following ballot position for
        draft-ietf-bess-evpn-inter-subnet-forwarding-09: No Objection

        When responding, please keep the subject line intact and reply to all
        email addresses included in the To and CC lines. (Feel free to cut this
        introductory paragraph, however.)

        Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
        for more information about IESG DISCUSS and COMMENT positions.

        The document, along with other ballot positions, can be found here:
        https://datatracker.ietf.org/doc/draft-ietf-bess-evpn-inter-subnet-forwarding/

        ----------------------------------------------------------------------
        COMMENT:
        ----------------------------------------------------------------------

        Thank you for the work put into this document.

        Please find below a couple of non-blocking COMMENTs (and I would appreciate a
        reply to each of my COMMENTs).

        I hope that this helps to improve the document,

        Regards,

        -éric

        PS: as a side note, I found that this document uses too many acronyms even for
        short words (e.g., "SN" instead of "Subnet"). There are also very long
        sentences that, when combined with acronyms, make reading difficult.

        == COMMENTS ==

        -- Section 2 --
        About "to bridge non-IP and intra-subnet traffic and to route inter-subnet IP
        traffic": suggest to clarify the text when the IP-VRF is IPv6 only, then, (I
        assume) that IPv4 packets will be bridged and not IP-forwarded (and vice-versa).

    [AS] the above quoted text is provided as an example and it should be clear enough
    Without making the sentence to verbose. 

        -- Section 4.1 --
        Suggest to replace "then the IRB interface MAC address MUST be the one used in
        the initial ARP reply or ND Neighbor Advertisement (NA) for that TS." by "then
        the IRB interface MAC address MUST be the one used in the initial ARP reply or
        ND Neighbor Advertisement (NA) or Router Advertisement (RA) for that TS"
        because routers MAC addresses are also advertised by Router Advertisements.

    [AS] I don't think the IRB interface MAC address in the initial ARP reply can be used 
    In RA because it is a multicast packet - i.e., the MAC address of old IRB interface and the
    New IRB interface cannot be sent in a single multicast packet.

        -- Section 5.1 --
        Should also mention NDP when writing "(via an ARP request)" in the first
        paragraph.

    [AS] Done.

        In the same vein, please add "NDP cache" to "Furthermore, it adds this TS's MAC
        and IP address association to its ARP table".

    [AS] Done.

        As I am not an expert in EVPN, I am puzzled by the math about the Length field
        "either 40 (if IPv4 address is carried) or 52 (if IPv6 address is carried)."

    [AS] for IPv6, the NLRI has 12 additional bytes.

        -- Section 5.2 --
        This section also only mentions IPv4 ARP table, please add IPv6 NDP cache.

    [AS] Done.

        -- Section 6.1 --
        Same comments as for section 5.1

    AS] Done.

        -- Section 6.2 --
        Same comments as for section 5.2

    [AS] Done.

        -- Section 7 --
        Good to state "Although the language used in this section is for IPv4 ARP, it
        equally applies to IPv6 ND."; even if I would have preferred to use by default
        IPv6 ND ;-)

    [AS] yes, the quoted sentence already exist. 

        Please note that in IPv6 there are often at least TWO IPv6 addresses per MAC
        (one link-local fe80::... and one global); so, "In the following subsections,
        it is assumed that the MAC and IP addresses of a TS have one-to-one
        relationship (i.e., there is one IP address per MAC address and vice versa). "
        is obviously never the case for IPv6. I understand that the rest of the
        paragraph explains how to handle the case but it could be easier to treat IPv6
        in a separate sentence.

        -- Section 7.1 --
        While about mobility, this section appears to be also applicable to Duplicate
        Address Detection but is unclear on what to do when the same IP but different
        MAC (i.e., an actual IP address collision). Or is it covered in other documents?

    [AS] duplicate MACs are covered in RFC 7432.

        == NITS ==

        -- Section 1 --
        "BD and subnet are equivalent terms" while in the rest of the document "IP
        subnet" is often used. If "subnet IP" and "subnet" are synonyms, then I suggest
        to keep using one for consistency or at least mention that "IP subnet" and
        "subnet" are the same concept (or explain the difference if they are not
        identical).

    [AS] Added clarification that "subnet" means "IP subnet".

---

From: "Ali Sajassi (sajassi)" <[email-masked]>
Date: Thu, 3 Sep 2020 16:39:57 +0000

Hi Eric,

I add the following sentences in section 2 to provide further clarification to your point:
" It should be
   noted that if an IP-VRF in a NVE is configured for IPv6 and that NVE
   receives IPv4 traffic on the corresponding VLAN, then the IPv4
   traffic is treated as L2 traffic and it is bridged.  Also vise versa,
   if an IP-VRF in a NVE is configured for IPv4 and that NVE receives
   IPv6 traffic on the corresponding VLAN, then the IPv6 traffic is
   treated as L2 traffic and it is bridged." 

Cheers,
Ali

On 9/1/20, 1:46 AM, "Eric Vyncke (evyncke)" <[email-masked]> wrote:

    Regards

    -éric

    -----Original Message-----
    From: "Ali Sajassi (sajassi)" <[email-masked]>
    Date: Tuesday, 1 September 2020 at 00:25
    To: Eric Vyncke <[email-masked]>, The IESG <[email-masked]>
    Cc: "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>, Zhaohui Zhang <[email-masked]>
    Subject: Re: Éric Vyncke's No Objection on draft-ietf-bess-evpn-inter-subnet-forwarding-09: (with COMMENT)

        Hi Eric,

            Regards,

            -éric

            == COMMENTS ==

            -- Section 2 --

            -- Section 4.1 --

            -- Section 5.1 --

        [AS] Done.

        [AS] Done.

            -- Section 5.2 --

        [AS] Done.

            -- Section 6.1 --

        AS] Done.

            -- Section 6.2 --

        [AS] Done.

            -- Section 7 --

            -- Section 7.1 --

            == NITS ==

            -- Section 1 --

---

From: "Eric Vyncke (evyncke)" <[email-masked]>
Date: Thu, 3 Sep 2020 18:12:59 +0000

Thank you Ali

The text should improve the quality of the document

Regards

-éric

-----Original Message-----
From: "Ali Sajassi (sajassi)" <[email-masked]>
Date: Thursday, 3 September 2020 at 18:39
To: Eric Vyncke <[email-masked]>, The IESG <[email-masked]>
Cc: "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>, Zhaohui Zhang <[email-masked]>
Subject: Re: Éric Vyncke's No Objection on draft-ietf-bess-evpn-inter-subnet-forwarding-09: (with COMMENT)

    Hi Eric,

    Cheers,
    Ali

        Regards

        -éric

        -----Original Message-----
        From: "Ali Sajassi (sajassi)" <[email-masked]>
        Date: Tuesday, 1 September 2020 at 00:25
        To: Eric Vyncke <[email-masked]>, The IESG <[email-masked]>
        Cc: "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>, Zhaohui Zhang <[email-masked]>
        Subject: Re: Éric Vyncke's No Objection on draft-ietf-bess-evpn-inter-subnet-forwarding-09: (with COMMENT)

            Hi Eric,

                Regards,

                -éric

                == COMMENTS ==

                -- Section 2 --

                -- Section 4.1 --

                -- Section 5.1 --

            [AS] Done.

            [AS] Done.

                -- Section 5.2 --

            [AS] Done.

                -- Section 6.1 --

            AS] Done.

                -- Section 6.2 --

            [AS] Done.

                -- Section 7 --

                -- Section 7.1 --

                == NITS ==

                -- Section 1 --