Re: [Detnet] Regarding the model for Active OAM packet

[Greg Mirsky <[e-mail]>]

 Hi Loa,
as I understand, for consistency of using GAL. PW ACH preceded GAL, which
primarily for LSP OAM.

Regards,
Greg

On Fri, Sep 21, 2018, 21:49 Loa Andersson <[e-mail]> wrote:

> Greg,
>
> If ACH is self-identifying, why do we ever need the GAL?
>
> /Loa
>
> On 2018-09-21 23:23, Greg Mirsky wrote:
> > Hi Loa,
> > you've asked how a node identifies that the payload is ACH, not CW. As I
> > understand RFC 4385, it is by the value of the first nibble that follows
> > BoS label. ACH assigned value 0b0001, PW CW - 0b0000. 0b0100 defines
> > IPv4, and 0b0110 - IPv6.
> >
> > Regards,
> > Greg
> >
> > On Fri, Sep 21, 2018 at 3:55 AM Loa Andersson <[e-mail]
> > <mailto:[e-mail]>> wrote:
> >
> >     Mach,
> >
> >     inline please
> >
> >     On 2018-09-21 18:31, Mach Chen wrote:
> >      > Hi Loa,
> >      >
> >      > New ACH type is fine, this is also needed for DetNet OAM, IMHO.
> >     The crucial here is how to "cheat" the replication/elimination nodes
> >     that an OAM packet is a "normal" DetNet packet, then they can
> >     replicate/eliminate the OAM packets as normal DetNet packets.
> >     Otherwise, it needs to introduce additional replication/elimination
> >     processing for the DetNet OAM packets.
> >      >
> >      > To support this, I suggest to use ACH without GAL (of cause, a
> >     new ACH-type) for DetNet OAM (as bellow) and the "reserved" field
> >     carries sequence number information, the "ACH" can be considered as
> >     the d-CW by the replication/elimination nodes.
> >      > +----------+
> >      > |S-Label  |
> >      > +----------+
> >      > |ACH        |
> >      > +----------+
> >      > | Payload|
> >      > +----------+
> >      >
> >     what info do a node use to understand that the ACH is an ACH??
> >
> >     /Loa
> >      > If GAL is used ( the stack as below), additional processing has
> >     to be introduced at the replication/elimination nodes, because they
> >     have to parse GAL+ACH to decide how to process. That means, the OAM
> >     packets will have different replication/elimination process from the
> >     normal DetNet packets.
> >      >
> >      > +----------+
> >      > |S-Label  |
> >      > +----------+
> >      > |GAL        |
> >      > +----------+
> >      > |ACH        |
> >      > +----------+
> >      > | Payload|
> >      > +----------+
> >      >
> >      > Best regards,
> >      > Mach
> >      >
> >      >> -----Original Message-----
> >      >> From: Loa Andersson [mailto:[e-mail] <mailto:[e-mail]>]
> >      >> Sent: Friday, September 21, 2018 4:49 PM
> >      >> To: Mach Chen <[e-mail]
> >     <mailto:[e-mail]>>; Greg Mirsky
> >      >> <[e-mail] <mailto:[e-mail]>>
> >      >> Cc: DetNet WG <[e-mail] <mailto:[e-mail]>>; János
> >     Farkas
> >      >> <[e-mail] <mailto:[e-mail]>>;
> >     [e-mail] <mailto:[e-mail]>
> >      >> Subject: Re: [Detnet] Regarding the model for Active OAM packet
> >      >>
> >      >> Mach,
> >      >>
> >      >> Admittedly I'm not up to speed on DetNet OAM, but .....
> >      >>
> >      >> The ACH is specified like this:
> >      >>
> >      >>       0                   1                   2
>  3
> >      >>       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8
> >     9 0 1
> >      >>
> >     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >      >>      |0 0 0 1|Version|   Reserved    |         Channel Type
> >          |
> >      >>
> >     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >      >>
> >      >> you can define 65k ACH-types, what stops you from defining a ACH
> >     channel
> >      >> type for DetNet OAM, then define that the structure of the
> >     following octets
> >      >> in a way that you see fit (like (yes I'm inventing as I type,
> >     more thoughts
> >      >> should go into to this):
> >      >>
> >      >>          0          1          2          3
> >      >>          0123 45678901 234567890123 45678901
> >      >>         +----+--------+------------+--------+
> >      >>         | R  |   LEN  |     relevant info   |
> >      >>         +----+--------+------------+--------+
> >      >>         |0000|             d-CW             |
> >      >>         +----+--------+------------+--------+
> >      >>         |        more relevant info         |
> >      >>         +----+--------+------------+--------+
> >      >>
> >      >>
> >      >> What is that I'm missing?
> >      >>
> >      >> /Loa
> >      >>
> >      >> On 2018-09-21 14:22, Mach Chen wrote:
> >      >>> Hi Loa,
> >      >>>
> >      >>> Can you clarify how a new ACH-type can address the problem?
> >      >>>
> >      >>> Best regards,
> >      >>> Mach
> >      >>>
> >      >>>> -----Original Message-----
> >      >>>> From: Loa Andersson [mailto:[e-mail] <mailto:[e-mail]>]
> >      >>>> Sent: Thursday, September 20, 2018 6:14 PM
> >      >>>> To: Mach Chen <[e-mail]
> >     <mailto:[e-mail]>>; Greg Mirsky
> >      >>>> <[e-mail] <mailto:[e-mail]>>
> >      >>>> Cc: DetNet WG <[e-mail] <mailto:[e-mail]>>;
> >     János Farkas
> >      >>>> <[e-mail]
> >     <mailto:[e-mail]>>; [e-mail]
> >     <mailto:[e-mail]>
> >      >>>> Subject: Re: [Detnet] Regarding the model for Active OAM packet
> >      >>>>
> >      >>>> Mach,
> >      >>>>
> >      >>>> I'd like Stewart or Matthew to look at this, but as I
> >     understand it
> >      >>>> it is possible to define a new ACH-type that can do exactly
> >     what you want.
> >      >>>>
> >      >>>> /Loa
> >      >>>>
> >      >>>> On 2018-09-20 17:58, Mach Chen wrote:
> >      >>>>> Loa,
> >      >>>>>
> >      >>>>> GAL is just an OAM indicator, the problem here is that when do
> >      >>>>> DetNet
> >      >>>> OAM, the d-CW will replaced by ACH or by GAL+ACH. No matter
> which
> >      >> way
> >      >>>> is used, to support the replication or elimination, there has
> >     to be a
> >      >>>> sequence number filed. But ACH (as its current defined) does
> >     not have
> >      >> such a field.
> >      >>>>>
> >      >>>>> My suggestion is to use the reserved field of ACH to carry
> >     sequence
> >      >>>> number of OAM packet,  and for those replication or elimination
> >      >>>> nodes, they do not have to differentiate whether a packet is
> OAM
> >      >>>> packet or a normal packet, they could just treat the right 28
> >     bits of
> >      >>>> the ACH as the sequence number ( or treat the ACH as the
> >     d-CW), then
> >      >>>> both OAM and replication/elimination can be supported.
> >      >>>>>
> >      >>>>> Best regards,
> >      >>>>> Mach
> >      >>>>>
> >      >>>>>> -----Original Message-----
> >      >>>>>> From: detnet [mailto:[e-mail]
> >     <mailto:[e-mail]>] On Behalf Of Loa
> >      >>>>>> Andersson
> >      >>>>>> Sent: Thursday, September 20, 2018 3:21 PM
> >      >>>>>> To: Mach Chen <[e-mail]
> >     <mailto:[e-mail]>>; Greg Mirsky
> >      >>>>>> <[e-mail] <mailto:[e-mail]>>
> >      >>>>>> Cc: DetNet WG <[e-mail] <mailto:[e-mail]>>;
> >     János Farkas
> >      >>>>>> <[e-mail]
> >     <mailto:[e-mail]>>; [e-mail]
> >     <mailto:[e-mail]>
> >      >>>>>> Subject: Re: [Detnet] Regarding the model for Active OAM
> packet
> >      >>>>>>
> >      >>>>>> Mach,
> >      >>>>>>
> >      >>>>>> If I understand you correctly this is for an LSP in an MPLS
> >      >>>>>> network, can you help me understand why GAL does not enough.
> >      >> Given
> >      >>>>>> that there might be some minor extensions to GAL because of
> >      >>>>>> replication and
> >      >>>> elimination.
> >      >>>>>>
> >      >>>>>> /Loa
> >      >>>>>>
> >      >>>>>> On 2018-09-19 14:31, Mach Chen wrote:
> >      >>>>>>> Hi Greg,
> >      >>>>>>>
> >      >>>>>>> Indeed, there is no DetNet Associated Channel defined in
> >      >>>>>>> draft-ietf-detnet-dp-sol-mpls for now, I think there should
> >     be.  I
> >      >>>>>>> also assume that PW ACH will be used for DetNet OAM.
> >      >>>>>>>
> >      >>>>>>> Assume that PW ACH will be used for DetNet OAM and the
> reserved
> >      >>>>>>> filed of the PW ACH will be used to carry sequence number
> >     for OAM
> >      >>>> packet.
> >      >>>>>>> But
> >      >>>>>>>      for PREF, a tricky way is to treat the “Version”+
> >     “Reserved” +
> >      >>>>>>> ”Channel type” as the Sequence number, the replication or
> >      >>>>>>> elimination nodes do not need to differentiate whether it
> is a
> >      >>>>>>> d-CW or  a
> >      >>>> PW ACH .
> >      >>>>>>> This way, OAM can be supported without additional
> >     processing and
> >      >>>> states.
> >      >>>>>>>
> >      >>>>>>>            0                   1                   2
> >      >>>>>>> 3
> >      >>>>>>>
> >      >>>>>>>            0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
> >     4 5 6 7
> >      >>>>>>> 8 9
> >      >>>>>>> 0
> >      >>>>>>> 1
> >      >>>>>>>
> >      >>>>>>>
> >      >>>>>>>
> >     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >      >>>>>>>
> >      >>>>>>>           |0 0 0 1|Verion |    Reserved   |         Channel
> >     Type
> >      >>>>>>> |
> >      >>>>>>>
> >      >>>>>>>
> >      >>>>>>>
> >     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >      >>>>>>>
> >      >>>>>>> Regarding sequence number, there are two ways to generate
> the
> >      >>>>>> sequence
> >      >>>>>>> number IMHO:  1) generated by the edge node, but it may
> need to
> >      >>>>>>> configure the start number, or 2) copied from the
> >     application-flow
> >      >>>>>>> (if there is). If the WG agree with this, the model can be
> >     updated
> >      >>>>>>> reflect this.
> >      >>>>>>>
> >      >>>>>>> Best regards,
> >      >>>>>>>
> >      >>>>>>> Mach
> >      >>>>>>>
> >      >>>>>>> *From:*Greg Mirsky [mailto:[e-mail]
> >     <mailto:[e-mail]>]
> >      >>>>>>> *Sent:* Wednesday, September 19, 2018 11:29 AM
> >      >>>>>>> *To:* Mach Chen <[e-mail]
> >     <mailto:[e-mail]>>
> >      >>>>>>> *Cc:* János Farkas <[e-mail]
> >     <mailto:[e-mail]>>; DetNet WG
> >      >>>>>>> <[e-mail] <mailto:[e-mail]>>;
> >     [e-mail] <mailto:[e-mail]>
> >      >>>>>>> *Subject:* Re: Regarding the model for Active OAM packet
> >      >>>>>>>
> >      >>>>>>> Hi Mach,
> >      >>>>>>>
> >      >>>>>>> thank you for your attention to my comment and the most
> >     expedient
> >      >>>>>> response.
> >      >>>>>>>
> >      >>>>>>> I don't find the DetNet Associated Channel defined in
> >      >>>>>>> draft-ietf-detnet-dp-sol-mpls and thus I assumed that OAM
> >     packets
> >      >>>>>>> that follow the data packet encapsulation defined in that
> draft
> >      >>>>>>> use PW ACH as defined in section 5 RFC 4385: True, it
> >     includes 8
> >      >>>>>>> bits-long Reserved field that may be defined as OAM Sequence
> >      >>>>>>> Number but that
> >      >>>>>> had
> >      >>>>>>> not been discussed. One is certain, existing nodes do not
> check
> >      >>>>>>> the Reserved field. And without a field to hold the sequence
> >      >>>>>>> number, PREF will not handle the OAM packets. Another
> question,
> >      >>>>>>> additional processing and amount of state introduced in the
> >     fast
> >      >>>>>>> path by the fact that OAM's Sequence Number will have
> different
> >      >>>>>>> length and location in d-CW (differentiating cases by the
> >     first nibble).
> >      >>>>>>>
> >      >>>>>>> Now, if we step back from DetnNet in MPLS data plane
> >      >>>>>>> encapsulation, why the control-word, as I understand, is
> >      >>>>>>> configurable? I think that the Sequence Number is not
> >      >>>>>>> configurable, nor the first nibble. What do you think?
> >      >>>>>>>
> >      >>>>>>> Regards,
> >      >>>>>>>
> >      >>>>>>> Greg
> >      >>>>>>>
> >      >>>>>>> On Tue, Sep 18, 2018 at 7:48 PM Mach Chen
> >      >> <[e-mail] <mailto:[e-mail]>
> >      >>>>>>> <mailto:[e-mail]
> >     <mailto:[e-mail]>>> wrote:
> >      >>>>>>>
> >      >>>>>>>        Hi Greg,
> >      >>>>>>>
> >      >>>>>>>        The MPLS DetNet header is defined as below:
> >      >>>>>>>
> >      >>>>>>>        grouping mpls-detnet-header {
> >      >>>>>>>             description
> >      >>>>>>>                 "The MPLS DetNet encapsulation header
> >     information.";
> >      >>>>>>>             leaf service-label {
> >      >>>>>>>               type uint32;
> >      >>>>>>>               mandatory true;
> >      >>>>>>>               description
> >      >>>>>>>                 "The service label of the DetNet header.";
> >      >>>>>>>             }
> >      >>>>>>>             leaf control-word {
> >      >>>>>>>               type uint32;
> >      >>>>>>>               mandatory true;
> >      >>>>>>>               description
> >      >>>>>>>                 "The control word of the DetNet header.";
> >      >>>>>>>             }
> >      >>>>>>>           }
> >      >>>>>>>
> >      >>>>>>>        Although do not consider Active OAM when design the
> >     above
> >      >>>>>>>        mpls-denet-header,  seems that it can cover Active
> >     OAM case as
> >      >> well.
> >      >>>>>>>        No matter a normal DetNet packet or an Active OAM
> >     packet, there
> >      >>>>>>>        should be a CW field, just as defined above.
> >      >>>>>>>
> >      >>>>>>>        For normal DetNet packets, the CW is the d-CW as
> >     defined in the
> >      >>>>>>>        draft-ietf-detnet-dp-sol-mpls.
> >      >>>>>>>
> >      >>>>>>>        For OAM packets, the CW is the "DetNet Associated
> >     Channel".
> >      >>>>>>>
> >      >>>>>>>        Best regards,
> >      >>>>>>>        Mach
> >      >>>>>>>
> >      >>>>>>>
> >      >>>>>>>        > -----Original Message-----
> >      >>>>>>>        > From: detnet [mailto:[e-mail]
> >     <mailto:[e-mail]>
> >      >>>>>>> <mailto:detnet- <mailto:detnet->
> >      >>>>>> [e-mail] <mailto:[e-mail]>>] On Behalf
> >      >>>>>>>        Of Greg Mirsky
> >      >>>>>>>        > Sent: Wednesday, September 19, 2018 3:17 AM
> >      >>>>>>>        > To: János Farkas <[e-mail]
> >     <mailto:[e-mail]>
> >      >>>>>> <mailto:[e-mail]
> >     <mailto:Janos.Farkas@ericsson..com>>>
> >      >>>>>>>        > Cc: DetNet WG <[e-mail]
> >     <mailto:[e-mail]> <mailto:[e-mail]
> >     <mailto:[e-mail]>>>;
> >      >>>>>>> detnet-
> >      >>>>>> [e-mail] <mailto:[e-mail]>
> >      >>>>>>>        <mailto:[e-mail]
> >     <mailto:[e-mail]>>
> >      >>>>>>>        > Subject: Re: [Detnet] WG adoption poll
> >      >>>>>>> draft-geng-detnet-conf-
> >      >>>> yang
> >      >>>>>>>        >
> >      >>>>>>>        > Hi Janos, et. al,
> >      >>>>>>>        > the mpls-detnet-header container is based on the
> >     solution
> >      >>>> described in
> >      >>>>>>>        > draft-ietf-detnet-dp-sol-mpls. Analysis of active
> >     SFC OAM
> >      >>>>>>> in the
> >      >>>>>> proposed
> >      >>>>>>>        > MPLS data plane solution in
> >     draft-mirsky-detnet-oam points
> >      >>>>>>> to the
> >      >>>>>> potential
> >      >>>>>>>        > problem as result the fact that OAM packet doesn't
> >     include
> >      >>>>>>> d-CW. I
> >      >>>>>> believe
> >      >>>>>>>        > that this question should be discussed and, if we
> >     agree on
> >      >>>>>>> the
> >      >>>> problem
> >      >>>>>>>        > statement, properly resolved. Until then, I do not
> >     support
> >      >>>>>>> the adoption
> >      >>>>>> of
> >      >>>>>>>        > the model that may not be capable to support
> >     active OAM.
> >      >>>>>>>        >
> >      >>>>>>>        > Regards,
> >      >>>>>>>        > Greg
> >      >>>>>>>        > On Tue, Sep 18, 2018 at 12:03 PM Janos Farkas
> >      >>>>>> <[e-mail]
> >     <mailto:[e-mail]> <mailto:[e-mail]
> >     <mailto:[e-mail]>>>
> >      >>>>>>>        > wrote:
> >      >>>>>>>        > >
> >      >>>>>>>        > > Dear all,
> >      >>>>>>>        > >
> >      >>>>>>>        > > This is start of a two week poll on making
> >      >>>>>>>        > > draft-geng-detnet-conf-yang-04 a working group
> >     document.
> >      >>>>>>> Please
> >      >>>>>> send
> >      >>>>>>>        > > email to the list indicating "yes/support" or
> >     "no/do not
> >      >>>> support".  If
> >      >>>>>>>        > > indicating no, please state your reservations
> >     with the
> >      >>>> document.  If
> >      >>>>>>>        > > yes, please also feel free to provide comments
> >     you'd like to see
> >      >>>>>>>        > > addressed once the document is a WG document.
> >      >>>>>>>        > >
> >      >>>>>>>        > > The poll ends Oct 3.
> >      >>>>>>>        > >
> >      >>>>>>>        > > Thanks,
> >      >>>>>>>        > > János and Lou
> >      >>>>>>>        > >
> >      >>>>>>>        > > _______________________________________________
> >      >>>>>>>        > > detnet mailing list
> >      >>>>>>>        > > [e-mail] <mailto:[e-mail]>
> >     <mailto:[e-mail] <mailto:[e-mail]>>
> >      >>>>>>>        > > https://www.ietf.org/mailman/listinfo/detnet
> >      >>>>>>>        >
> >      >>>>>>>        > _______________________________________________
> >      >>>>>>>        > detnet mailing list
> >      >>>>>>>        > [e-mail] <mailto:[e-mail]>
> >     <mailto:[e-mail] <mailto:[e-mail]>>
> >      >>>>>>>        > https://www.ietf.org/mailman/listinfo/detnet
> >      >>>>>>>
> >      >>>>>>>
> >      >>>>>>>
> >      >>>>>>> _______________________________________________
> >      >>>>>>> detnet mailing list
> >      >>>>>>> [e-mail] <mailto:[e-mail]>
> >      >>>>>>> https://www.ietf.org/mailman/listinfo/detnet
> >      >>>>>>>
> >      >>>>>>
> >      >>>>>> --
> >      >>>>>>
> >      >>>>>>
> >      >>>>>> Loa Andersson                        email: [e-mail]
> >     <mailto:[e-mail]>
> >      >>>>>> Senior MPLS Expert
> >      >>>>>> Bronze Dragon Consulting             phone: [phone]
> >      >>>>>>
> >      >>>>>> _______________________________________________
> >      >>>>>> detnet mailing list
> >      >>>>>> [e-mail] <mailto:[e-mail]>
> >      >>>>>> https://www.ietf.org/mailman/listinfo/detnet
> >      >>>>> _______________________________________________
> >      >>>>> detnet mailing list
> >      >>>>> [e-mail] <mailto:[e-mail]>
> >      >>>>> https://www.ietf.org/mailman/listinfo/detnet
> >      >>>>>
> >      >>>>
> >      >>>> --
> >      >>>>
> >      >>>>
> >      >>>> Loa Andersson                        email: [e-mail]
> >     <mailto:[e-mail]>
> >      >>>> Senior MPLS Expert
> >      >>>> Bronze Dragon Consulting             phone: [phone]
> >      >>
> >      >> --
> >      >>
> >      >>
> >      >> Loa Andersson                        email: [e-mail]
> >     <mailto:[e-mail]>
> >      >> Senior MPLS Expert
> >      >> Bronze Dragon Consulting             phone: [phone]
> >      > _______________________________________________
> >      > detnet mailing list
> >      > [e-mail] <mailto:[e-mail]>
> >      > https://www.ietf.org/mailman/listinfo/detnet
> >      >
> >
> >     --
> >
> >
> >     Loa Andersson                        email: [e-mail] <mailto:
> [e-mail]>
> >     Senior MPLS Expert
> >     Bronze Dragon Consulting             phone: [phone]
> >
> >
> >
> > _______________________________________________
> > detnet mailing list
> > [e-mail]
> > https://www.ietf.org/mailman/listinfo/detnet
> >
>
> --
>
>
> Loa Andersson                        email: [e-mail]
> Senior MPLS Expert
> Bronze Dragon Consulting             phone: [phone]
>