Re: [sfc] New Version Notification for draft-vandevelde-sfc-nsh-length-overload-00.txt

See inline: GV>

On 17/10/2016, 18:10, "Dave Dolson" <ddolson@sandvine.com> wrote:

    I would prefer to see the length field always mean length, so that implementations not requiring metadata can just skip the metadata regardless of MD type. 

GV> There is indeed something to say for that. However, For a NSH Type-1 MD allocation , the length field has no real contributing value, beyond containing the number 0x06. 

    At the risk of stating the obvious, there already is an MD type field that can be used to discriminate metadata allocations. Values 3,4,5,... are available for different MD encodings.

GV> And this would be fine also… current issue is that the way NSH MD Type-1 is currently defined it is considered as Opaque content data, and the allocation scheme is part left out from NSH definition… If for each of the allocation schemes a new MD type is allocated, then each SF can identify how to read the MD fields and the meta-data field in stateless universal fashion and life is easy and consistent… however, the current reality is different.

G/

--------------------------------------------------------------------------------

it is progressed currently for the allocation 

    -Dave

    ________________________________________
    From: sfc [sfc-bounces@ietf.org] on behalf of Ron Parker [Ron_Parker@affirmednetworks.com]
    Sent: Monday, October 17, 2016 10:50 AM
    To: Van De Velde, Gunter (Nokia - BE); sfc@ietf.org
    Subject: Re: [sfc] New Version Notification for draft-vandevelde-sfc-nsh-length-overload-00.txt

    Gunter,

    I strongly support this proposal.   It brings more specificity to Type 1 which will undoubtedly improve interworking between different implementations and between different administrative domains.

       Ron

    -----Original Message-----
    From: sfc [mailto:sfc-bounces@ietf.org] On Behalf Of Van De Velde, Gunter (Nokia - BE)
    Sent: Monday, October 17, 2016 5:15 AM
    To: sfc@ietf.org
    Subject: [GRAYMAIL] [sfc] FW: New Version Notification for draft-vandevelde-sfc-nsh-length-overload-00.txt

    Short text about overloading NSH length field for NSH MD Type-1 as context allocation type, including proposal for backward compatibility.

    G/

    ------

    On 17/10/2016, 10:05, "internet-drafts@ietf.org" <internet-drafts@ietf.org> wrote:

        A new version of I-D, draft-vandevelde-sfc-nsh-length-overload-00.txt
        has been successfully submitted by Gunter Van de Velde and posted to the
        IETF repository.

        Name:               draft-vandevelde-sfc-nsh-length-overload
        Revision:   00
        Title:              Network Services Header Context Allocation Identifier
        Document date:      2016-10-17
        Group:              Individual Submission
        Pages:              5
        URL:            https://www.ietf.org/internet-drafts/draft-vandevelde-sfc-nsh-length-overload-00.txt
        Status:         https://datatracker.ietf.org/doc/draft-vandevelde-sfc-nsh-length-overload/
        Htmlized:       https://tools.ietf.org/html/draft-vandevelde-sfc-nsh-length-overload-00

        Abstract:
           The specification of the NSH MD Type 1 header [draft-ietf-sfc-nsh]
           mandates four Context Headers, 4-byte each, and they MUST be added
           immediately following the Service Path Header.  As direct
           consequence, an NSH MD Type 1 header is always Length 0x6 (six 4-byte
           words).  As a result, the Length field of the NSH MD Type 1 header
           provides an information which is known by simply looking at the "MD
           Type" field.  However, while [draft-ietf-sfc-nsh] does not specify
           the encoding of these Context Headers, other specifications have
           started to do so.  A need to distinguish types of Context Headers
           therefore arises.

           This draft proposes to overload the Length field of an NSH MD Type 1
           as Meta-Data context allocation identifier and to create a IANA
           repository for NSH MD Type 1 allocation schemes.  The NSH MD Type 1
           Length field overload intends to allow universal understanding at any
           network location and by any network device of the context allocation
           structure.

        Please note that it may take a couple of minutes from the time of submission
        until the htmlized version and diff are available at tools.ietf.org.

        The IETF Secretariat

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