Re: [bess] AD Review of draft-ietf-bess-evpn-vpws-07

Agree with Patrice.

The initial value was coming from the RFC7432 spec:

“An Ethernet Tag ID is a 32-bit field containing either a 12-bit or
   24-bit identifier that identifies a particular broadcast domain
   (e.g., a VLAN) in an EVPN instance.”

And now there are a few implementations out there that may check that the eth-tag is 24 bits and not larger. 
I prefer low order 24-bits rather than right aligned…

Thanks.
Jorge

On 2/22/17, 3:39 AM, "BESS on behalf of Patrice Brissette (pbrisset)" <bess-bounces@ietf.org on behalf of pbrisset@cisco.com> wrote:

    Himanshu,

    I don’t think we should make the Eth-tag a MUST be 24 bit. It should be MAY  but if you decide to use 24 bits, it MUST be right aligned.

    Regards,
    Patrice Brissette

    On 2017-02-21, 2:51 PM, "Shah, Himanshu" <hshah@ciena.com> wrote:

        ‘MAY’ does not work. 
        It has to be ‘MUST’, IMO. 

        Thanks,
        Himanshu

        On 2/21/17, 2:22 PM, "BESS on behalf of Patrice Brissette (pbrisset)" <bess-bounces@ietf.org on behalf of pbrisset@cisco.com> wrote:

            Folks,

            Why don’t we simply mention that the Eth–Tag is a 32 bit value and MAY be set to a 24 bits instance
            When 24 bits value is used is MAY be right aligned.

            Regards,
            Patrice Brissette

            On 2017-02-21, 2:18 PM, "BESS on behalf of Sami Boutros" <bess-bounces@ietf.org on behalf of sboutros@vmware.com> wrote:

                Hi John,

                I can add that the value is from 0 to 0x00ffffff, will that work?

                Thanks,

                Sami
                On 2/21/17, 10:56 AM, "John E Drake" <jdrake@juniper.net> wrote:

                >Sami,
                >
                >Snipped, comment inline
                >
                >Yours Irrespectively,
                >
                >John
                >
                >> >
                >> >> Ethernet Tag ID 32-bit field MUST be set to the 24-bit VPWS service instance
                >> identifier value."
                >> >
                >> >
                >> >
                >> >Ok, but you still didn’t mention how the 24-bit value is to be aligned in the 32-
                >> bit field.  I’m guessing there will be some 0-padding, but will that the at the
                >> beginning or the end?
                >> >
                >> 
                >> I made the VPWS service instance identifier a 32-bit value in the new draft.
                >> 
                >
                >[JD]   I don't think you can do this as there are multiple implementations that use 24 bits  
                >
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