Re: Gen-ART review of draft-ietf-mpls-tp-ethernet-addressing-05

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On 02/04/2013 15:28, Richard Barnes wrote:
Thanks for following up, and for the re-send. Just to be clear, I do not mean these as blocking points.

On the former point, I might just suggest a minor edit to the introduction: OLD: "This document specifies the options for determination and selection of next-hop Ethernet MAC addressing under these circumstances." NEW: "This document specifies the options for determination and selection of next-hop Ethernet MAC addressing when MPLS-TP is used in a "pure Ethernet" manner, without any IP forwarding capability."

After various rounds of tweeking:

"This document specifies the options for the determination and selection of the next-hop Ethernet MAC address when MPLS-TP is used between nodes that do not have an IP dataplane."

The subtly is the network may be mixed IP capable and non-IP capable.



On the latter point, I can understand the desire to make the simple case simple, and the text at the end of Section 2 sends a clear warning. It does seems like GAP would also allow autoconfiguration without further NMS interaction. (Unless the NMS is configuring per-Ethernet-address policies, e.g., "forward packets with this label to 00:11:22:33:44:55". Is that the case?)
Yes. One case is a network that is generally NMS configured, and wants to use unicast MAC addresses, but wants to allow the craft people to plug in a new linecard without talking to the NMS. In such circumstances the only auto config would be teh MAC addresses.

Stewart





On Tue, Apr 2, 2013 at 9:10 AM, Stewart Bryant <stbryant@xxxxxxxxx <mailto:stbryant@xxxxxxxxx>> wrote:

    Resending due to Richards change of address.

    Stewart


    On 11/02/2013 23:45, Richard Barnes wrote:
    I have been selected as the General Area Review Team (Gen-ART)
    reviewer for this draft (for background on Gen-ART,
    pleaseseehttp://www.alvestrand.no/ietf/gen/art/gen-art-FAQ.html
    <http://www.alvestrand.no/ietf/gen/art/gen-art-FAQ.html>). Please
    wait for direction from your document shepherd or AD before
    posting a new version of the draft. Document:
    draft-ietf-mpls-tp-ethernet-
    addressing-05
    Reviewer: Richard Barnes
    Review Date: 2013-02-11
    IETF LC End Date: 2013-02-18
    IESG Telechat date: TBD

    Summary:  Ready, with a couple of minor questions / clarifications.

    Comment:

    The document is mostly very clearly written.  (Thanks!)  It would have helped me understand if it could have been clarified up front that the mechanism in this document is intended for "pure Ethernet" MPLS-TP (without assumptions about layer 3+).  The current introduction says as much, but in a negative way, in terms of ARP or ND not being available.

    I have some minor unease about the distinction that this document makes between point-to-point and multipoint links.  The document correctly notes that a point-to-point link might become multipoint without either end being aware.  I would have thought this would argue for using GAP in all cases, but instead the document carries on with addressing the point-to-point case separately..

    Richard

    It is always difficult when writing a simple draft dealing with a
    small
    component of a larger technology to know how much tutorial to include,
    but I believe the point about operation in the absence IP would be
    well known
    to anyone implementing this. In particular we assume that anyone
    implementing the draft would have read the required references called
    up in the first paragraph of the Introduction:


    " The MPLS Transport Profile (MPLS-TP) [RFC5921] is the set of
    protocol
    functions that meet the requirements [RFC5654] for the application of
    MPLS to the construction and operation of packet-switched transport
    networks. The MPLS-TP data plane consists of those MPLS-TP functions
    concerned with the encapsulation and forwarding of MPLS-TP packets
    and is described in [RFC5960]."

    RFC5654 says:

    "   36  It MUST be possible to operate and configure the MPLS-TP data
            plane without any IP forwarding capability in the MPLS-TP data
            plane.  That is, the data plane only operates on the MPLS label."
    Thus I think that the text is complete as it stands and requires no
    further clarification for anyone that needs to consider the technology
    it describes.


    With regard to your second point, the issue that we are have, is that
    there are a number of deployment scenarios where the operator knows
    that the link is Pt-Pt, and there is a reluctance by that community to
    use anything other than NMS configuration. That has lead them
    to use Ethernet broadcast addressing which allows the crafts to
    change h/w without the need for reconfiguration by the NMS.
    Against that background moving them onto the use of a Ethernet m/c
    address is a step forward. To require using the GAP to that
    community would illustrate that the IETF is out of touch with
    their needs and methods of network operation.

    Hopefully this additional background, which I believe is well
    known to the MPLS-TP community to which this draft is directed,
    satisfies your concern on the latter point.

    - Stewart



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