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

Greg Mirsky <gregimirsky@gmail.com> Fri, 21 September 2018 15:30 UTC

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From: Greg Mirsky <gregimirsky@gmail.com>
Date: Fri, 21 Sep 2018 08:30:14 -0700
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To: Loa Andersson <loa@pi.nu>
Cc: Mach Chen <mach.chen@huawei.com>, DetNet WG <detnet@ietf.org>, János Farkas <Janos.Farkas@ericsson.com>, detnet-chairs@ietf.org, Stewart Bryant <stewart.bryant@gmail.com>, "Bocci, Matthew (Nokia - GB)" <matthew.bocci@nokia.com>
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Subject: Re: [Detnet] Regarding the model for Active OAM packet
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Hi Loa,
DetNet OAM, in my view, is not another OAM function but includes FM and PM
OAM functions we have in any networking layer, e.g., IP or MPLS. I believe
we must have on-demand and proactive Fault Management OAM, as well as
Performance Monitoring OAM tool(s). Also, because of PREF, on-demand OAM
must be extended. Hence, my thought that BFD, RFC 6374, etc. ACH types may
be re-used on DetNet layer.

Regards,
Greg

On Fri, Sep 21, 2018 at 3:44 AM Loa Andersson <loa@pi.nu> wrote:

> Greg,
>
> On 2018-09-20 20:55, Greg Mirsky wrote:
> > Hi Loa,
> > I agree that we can define new ACH Type that will have Sequence Number
> > immediately following the ACH.
>
> OK!
>
>     > But then we'll need to re-define number
> > of Types, e.g., BFD, RFC 6374, etc. Or I misunderstood
> your suggestion.this probably
> >
> This probably the key, why do you need to redefine?
>
> /Loa
> > Regards,
> > Greg
> >
> > On Thu, Sep 20, 2018 at 3:13 AM Loa Andersson <loa@pi.nu
> > <mailto:loa@pi.nu>> wrote:
> >
> >     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:detnet-bounces@ietf.org
> >     <mailto:detnet-bounces@ietf.org>] On Behalf Of Loa Andersson
> >      >> Sent: Thursday, September 20, 2018 3:21 PM
> >      >> To: Mach Chen <mach.chen@huawei.com
> >     <mailto:mach.chen@huawei.com>>; Greg Mirsky
> >      >> <gregimirsky@gmail.com <mailto:gregimirsky@gmail.com>>
> >      >> Cc: DetNet WG <detnet@ietf.org <mailto:detnet@ietf.org>>; János
> >     Farkas
> >      >> <Janos.Farkas@ericsson.com <mailto:Janos.Farkas@ericsson.com>>;
> >     detnet-chairs@ietf.org <mailto:detnet-chairs@ietf.org>
> >      >> 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:gregimirsky@gmail.com
> >     <mailto:gregimirsky@gmail.com>]
> >      >>> *Sent:* Wednesday, September 19, 2018 11:29 AM
> >      >>> *To:* Mach Chen <mach.chen@huawei.com
> >     <mailto:mach.chen@huawei.com>>
> >      >>> *Cc:* János Farkas <Janos.Farkas@ericsson.com
> >     <mailto:Janos.Farkas@ericsson.com>>; DetNet WG
> >      >>> <detnet@ietf.org <mailto:detnet@ietf.org>>;
> >     detnet-chairs@ietf.org <mailto:detnet-chairs@ietf.org>
> >      >>> *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 <mach.chen@huawei.com
> >     <mailto:mach.chen@huawei.com>
> >      >>> <mailto:mach.chen@huawei.com <mailto:mach.chen@huawei.com>>>
> 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:detnet-bounces@ietf.org
> >     <mailto:detnet-bounces@ietf.org> <mailto:detnet- <mailto:detnet->
> >      >> bounces@ietf.org <mailto:bounces@ietf.org>>] On Behalf
> >      >>>      Of Greg Mirsky
> >      >>>      > Sent: Wednesday, September 19, 2018 3:17 AM
> >      >>>      > To: János Farkas <Janos.Farkas@ericsson.com
> >     <mailto:Janos.Farkas@ericsson.com>
> >      >> <mailto:Janos.Farkas@ericsson.com
> >     <mailto:Janos.Farkas@ericsson.com>>>
> >      >>>      > Cc: DetNet WG <detnet@ietf.org <mailto:detnet@ietf.org>
> >     <mailto:detnet@ietf.org <mailto:detnet@ietf.org>>>; detnet-
> >      >> chairs@ietf.org <mailto:chairs@ietf.org>
> >      >>>      <mailto:detnet-chairs@ietf.org
> >     <mailto:detnet-chairs@ietf.org>>
> >      >>>      > 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
> >      >> <Janos.Farkas@ericsson.com <mailto:Janos.Farkas@ericsson.com>
> >     <mailto:Janos.Farkas@ericsson.com <mailto:Janos.Farkas@ericsson.com
> >>>
> >      >>>      > 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
> >      >>>      > > detnet@ietf.org <mailto:detnet@ietf.org>
> >     <mailto:detnet@ietf.org <mailto:detnet@ietf.org>>
> >      >>>      > > https://www.ietf.org/mailman/listinfo/detnet
> >      >>>      >
> >      >>>      > _______________________________________________
> >      >>>      > detnet mailing list
> >      >>>      > detnet@ietf.org <mailto:detnet@ietf.org>
> >     <mailto:detnet@ietf.org <mailto:detnet@ietf.org>>
> >      >>>      > https://www.ietf.org/mailman/listinfo/detnet
> >      >>>
> >      >>>
> >      >>>
> >      >>> _______________________________________________
> >      >>> detnet mailing list
> >      >>> detnet@ietf.org <mailto:detnet@ietf.org>
> >      >>> https://www.ietf.org/mailman/listinfo/detnet
> >      >>>
> >      >>
> >      >> --
> >      >>
> >      >>
> >      >> Loa Andersson                        email: loa@pi.nu
> >     <mailto:loa@pi.nu>
> >      >> Senior MPLS Expert
> >      >> Bronze Dragon Consulting             phone: +46 739 81 21 64
> >      >>
> >      >> _______________________________________________
> >      >> detnet mailing list
> >      >> detnet@ietf.org <mailto:detnet@ietf.org>
> >      >> https://www.ietf.org/mailman/listinfo/detnet
> >      > _______________________________________________
> >      > detnet mailing list
> >      > detnet@ietf.org <mailto:detnet@ietf.org>
> >      > https://www.ietf.org/mailman/listinfo/detnet
> >      >
> >
> >     --
> >
> >
> >     Loa Andersson                        email: loa@pi.nu <mailto:
> loa@pi.nu>
> >     Senior MPLS Expert
> >     Bronze Dragon Consulting             phone: +46 739 81 21 64
> >
>
> --
>
>
> Loa Andersson                        email: loa@pi.nu
> Senior MPLS Expert
> Bronze Dragon Consulting             phone: +46 739 81 21 64
>