Re: [Detnet] Regarding the model for Active OAM packet
Loa Andersson <loa@pi.nu> Thu, 20 September 2018 10:14 UTC
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To: Mach Chen <mach.chen@huawei.com>, Greg Mirsky <gregimirsky@gmail.com>
Cc: DetNet WG <detnet@ietf.org>, János Farkas <Janos.Farkas@ericsson.com>, "detnet-chairs@ietf.org" <detnet-chairs@ietf.org>, Stewart Bryant <stewart.bryant@gmail.com>, "matthew.bocci@alcatel-lucent.com" <matthew.bocci@alcatel-lucent.com>
References: <F73A3CB31E8BE34FA1BBE3C8F0CB2AE29267092D@dggeml530-mbs.china.huawei.com> <CA+RyBmX29+Q9y3dXM-PqYm-Nu8KtjYZDs6a-fh_rW5hacSpyRg@mail.gmail.com> <F73A3CB31E8BE34FA1BBE3C8F0CB2AE292672CBB@dggeml530-mbs.china.huawei.com> <d4e45e7d-1001-be64-9ff0-f9ea9a882b77@pi.nu> <F73A3CB31E8BE34FA1BBE3C8F0CB2AE292673B40@dggeml530-mbs.china.huawei.com>
From: Loa Andersson <loa@pi.nu>
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Date: Thu, 20 Sep 2018 18:14:06 +0800
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Subject: Re: [Detnet] Regarding the model for Active OAM packet
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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] On Behalf Of Loa Andersson >> Sent: Thursday, September 20, 2018 3:21 PM >> To: Mach Chen <mach.chen@huawei.com>; Greg Mirsky >> <gregimirsky@gmail.com> >> Cc: DetNet WG <detnet@ietf.org>; János Farkas >> <Janos.Farkas@ericsson.com>; 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] >>> *Sent:* Wednesday, September 19, 2018 11:29 AM >>> *To:* Mach Chen <mach.chen@huawei.com> >>> *Cc:* János Farkas <Janos.Farkas@ericsson.com>; DetNet WG >>> <detnet@ietf.org>; 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>> 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>] 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>> >>> > Cc: DetNet WG <detnet@ietf.org <mailto:detnet@ietf.org>>; 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>> >>> > 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> >>> > > https://www.ietf.org/mailman/listinfo/detnet >>> > >>> > _______________________________________________ >>> > detnet mailing list >>> > detnet@ietf.org <mailto:detnet@ietf.org> >>> > https://www.ietf.org/mailman/listinfo/detnet >>> >>> >>> >>> _______________________________________________ >>> detnet mailing list >>> detnet@ietf.org >>> https://www.ietf.org/mailman/listinfo/detnet >>> >> >> -- >> >> >> Loa Andersson email: loa@pi.nu >> Senior MPLS Expert >> Bronze Dragon Consulting phone: +46 739 81 21 64 >> >> _______________________________________________ >> detnet mailing list >> detnet@ietf.org >> https://www.ietf.org/mailman/listinfo/detnet > _______________________________________________ > detnet mailing list > detnet@ietf.org > https://www.ietf.org/mailman/listinfo/detnet > -- Loa Andersson email: loa@pi.nu Senior MPLS Expert Bronze Dragon Consulting phone: +46 739 81 21 64
- [Detnet] Regarding the model for Active OAM packet Mach Chen
- Re: [Detnet] Regarding the model for Active OAM p… Greg Mirsky
- Re: [Detnet] Regarding the model for Active OAM p… Mach Chen
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Mach Chen
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Greg Mirsky
- Re: [Detnet] Regarding the model for Active OAM p… Mach Chen
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Mach Chen
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Greg Mirsky
- Re: [Detnet] Regarding the model for Active OAM p… Greg Mirsky
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Greg Mirsky
- Re: [Detnet] Regarding the model for Active OAM p… Loa Andersson
- Re: [Detnet] Regarding the model for Active OAM p… Greg Mirsky
- Re: [Detnet] Regarding the model for Active OAM p… Mach Chen