Re: [Lsr] Working Group Last Call for draft-ietf-lsr-ip-flexalgo-04 - "IGP Flexible Algorithms (Flex-Algorithm) In IP Networks"

["Les Ginsberg (ginsberg)" <[e-mail]>]

Peter -



I am in agreement.



However, the IANA section of the draft is missing some necessary information.

The new top level TLVs in IS-IS - I am assuming you want these to share the sub-TLV space defined in https://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv-codepoints.xhtml#isis-tlv-codepoints-advertising-prefix-reachability

In which case you need to provide a list of the existing sub-TLVs and an indication (Y/N) as to whether they are allowed in the new TLVs.



Here is my initial take:



1    32-bit Administrative Tag Sub-TLV    Y

2    64-bit Administrative Tag Sub-TLV    y

3    Prefix Segment Identifier            n

4    Prefix Attribute Flags              y

5    SRv6 End SID                        n

6    Flex-Algorithm Prefix Metric        n

11   IPv4 Source Router ID               y

12   IPv6 Source Router ID               y

32   BIER Info                          n(??)



    Les



> -----Original Message-----

> From: Lsr <[e-mail]> On Behalf Of Peter Psenak

> Sent: Tuesday, May 3, 2022 7:14 AM

> To: Aijun Wang <[e-mail]>; Peter Psenak

> <ppsenak=[e-mail]>

> Cc: Acee Lindem (acee) <acee=[e-mail]>; [e-mail];

> [e-mail]

> Subject: Re: [Lsr] Working Group Last Call for draft-ietf-lsr-ip-flexalgo-04 -

> "IGP Flexible Algorithms (Flex-Algorithm) In IP Networks"

>

> Aijun,

>

> On 03/05/2022 15:52, Aijun Wang wrote:

> > Hi, Peter:

> > I think the logic is the following:

> > FAPM is the sub-TLV of TLV 135,235,236 and 237, then it extends these TLVs

> for advertising prefixes in algorithm 0 to other Flexible Algorithm.

> > Then I see no reason to define the new top-TLV to encoding the similar

> information.

>

> FAPM is used in SR-MPLS case where algo 0 prefix has multiple flex-algo

> SIDs. So the algo 0 reachability is always advertised in legacy TLV and

> FAPM is used to advertise additional flex-algo metric for inter-area or

> external prefixes.

>

> We can not use it for IP flex-algo.

>

> thanks,

> Peter

>

> >

> > Aijun Wang

> > China Telecom

> >

> >> On May 3, 2022, at 19:16, Peter Psenak

> <ppsenak=[e-mail]<mailto:ppsenak=[e-mail]>> wrote:

> >>

> >> Hi Aijun,

> >>

> >>> On 03/05/2022 11:57, Aijun Wang wrote:

> >>> Hi, Peter：

> >>> Different data planes use different Flex-Algorithm and associated

> metric, they can’t be mixed.

> >>> Or, would you like to point out why the following scenarios can’t be

> achieved via the FAPM?

> >>> 1) The PE router has three loopback addresses(Lo1-Lo3), each associated

> with different Flex-ALgorithhms, and also different metrics. They are

> advertised via the FAPM, no MPLS SIDs are associated with these loopack

> prefixes advertisements.

> >>> 2) The PE router has also another inter-area/inter-domain

> prefixes(IPextra), with the FAPM and MPLS SID advertised via the prefixes

> advertisements.

> >>> When the PE in other ends want to send the traffic to theses addresses:

> >>> 1)  To the formers three destinations(Lo1-Lo3), the FIB that are formed

> by the associated FAPM will be used, that is, the IP-based forwarding will be

> selected.

> >>> 2) To the Inter-area/inter-domain prefixes the FIB that are formed via

> the FAPM and the associated SID, the MPLS-based forwarding will be

> selected.

> >>> Why can’t they coexist?

> >>

> >> FAPM Sub-TLV is a sub-TLV of TLVs 135, 235, 236, and 237. These TLVs

> advertise the reachability of the prefix in algorithm 0.

> >>

> >> For an IP algo prefix, which is associated with the flex-algorithm, the

> reachability in algorithm 0 must not be advertised. So we have to use a

> different top level TLV.

> >>

> >>

> >> thanks,

> >> Peter

> >>

> >>

> >>

> >>> Aijun Wang

> >>> China Telecom

> >>>>> On May 3, 2022, at 16:05, Peter Psenak

> <ppsenak=[e-mail]<mailto:ppsenak=[e-mail]>> wrote:

> >>>>

> >>>> Aijun,

> >>>>

> >>>>> On 03/05/2022 09:59, Aijun Wang wrote:

> >>>>> Hi, Peter:

> >>>>> The definition of FAPM for IS-IS and OSPF doesn’t prevent from it is

> used for the intra-area prefixes.

> >>>>> If we advertise the different loopback addresses via the FAPM,

> associate them to different Flex-Algo and related metrics, and does not

> allocate the MPLS SID, we can achieve the IP-Flex effect then.

> >>>>

> >>>> as I said, we can not mix metrics for different data-planes.

> >>>>

> >>>>> So, what’s the additional value of the IP-Flexalgo draft then?

> >>>>

> >>>> please read the draft. It defines the flex-algo for IP data plane.

> >>>>

> >>>> thanks,

> >>>> Peter

> >>>>

> >>>>

> >>>>

> >>>>> Aijun Wang

> >>>>> China Telecom

> >>>>>>> On May 3, 2022, at 14:46, Peter Psenak

> <ppsenak=[e-mail]<mailto:ppsenak=[e-mail]>> wrote:

> >>>>>>

> >>>>>> Aijun,

> >>>>>>

> >>>>>>> On 03/05/2022 00:47, Aijun Wang wrote:

> >>>>>>> Hi, Acee:

> >>>>>>> The questions raised at

> https://mailarchive.ietf.org/arch/msg/lsr/RlHphXCwxMbgGvcBV_m24xiDzS0<https://mailarchive.ietf.org/arch/msg/lsr/RlHphXCwxMbgGvcBV_m24xiDzS0/>

> /<https://mailarchive.ietf.org/arch/msg/lsr/RlHphXCwxMbgGvcBV_m24xiDzS0/>

> <https://mailarchive.ietf.org/arch/msg/lsr/RlHphXCwxMbgGvcBV_m24xiDzS<https://mailarchive.ietf.org/arch/msg/lsr/RlHphXCwxMbgGvcBV_m24xiDzS0/>

> 0/<https://mailarchive.ietf.org/arch/msg/lsr/RlHphXCwxMbgGvcBV_m24xiDzS0/>> has not been answered.

> >>>>>>

> >>>>>> IS-IS Flexible Algorithm Prefix Metric Sub-TLV” and “OSPF Flexible

> Algorithm Prefix Metric Sub-TLV” are defined for advertisement of algorithm

> specific metric for inter-area inter-AS prefixes for SR-MPLS data-plane.

> >>>>>>

> >>>>>> SR MPLS and IP are independent data-planes used for flex-algo. We

> can not mix their metric.

> >>>>>>

> >>>>>> thanks,

> >>>>>> Peter

> >>>>>>

> >>>>>>> Aijun Wang

> >>>>>>> China Telecom

> >>>>>>>>> On May 2, 2022, at 23:00, Acee Lindem (acee)

> <acee=[e-mail]<mailto:acee=[e-mail]>> wrote:

> >>>>>>>>

> >>>>>>>> The WG last call has completed. We will submit an updated

> version of the document for publication with the terminology changes based

> on the discussion amongst the authors, Ketan, Robert, Gyan, and others.

> >>>>>>>>

> >>>>>>>> Thanks,

> >>>>>>>> Acee

> >>>>>>>>

> >>>>>>>> *From: *Lsr <[e-mail]<mailto:[e-mail]>> on behalf of "Acee Lindem

> (acee)" <acee=[e-mail]<mailto:acee=[e-mail]>>

> >>>>>>>> *Date: *Thursday, April 7, 2022 at 3:07 PM

> >>>>>>>> *To: *"[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>

> >>>>>>>> *Cc: *"[e-mail]<mailto:[e-mail]>" <draft-ietf-lsr-ip-<mailto:[e-mail]>

> [e-mail]<mailto:[e-mail]>>

> >>>>>>>> *Subject: *[Lsr] Working Group Last Call for draft-ietf-lsr-ip-

> flexalgo-04 - "IGP Flexible Algorithms (Flex-Algorithm) In IP Networks"

> >>>>>>>>

> >>>>>>>> This begins a WG last call for draft-ietf-lsr-ip-flexalgo-04.  The draft

> had a lot of support and discussion initially and has been stable for some

> time. Please review and send your comments, support, or objection to this

> list before 12 AM UTC on April 22^nd , 2022.

> >>>>>>>>

> >>>>>>>> Thanks,

> >>>>>>>> Acee

> >>>>>>>>

> >>>>>>>> _______________________________________________

> >>>>>>>> Lsr mailing list

> >>>>>>>> [e-mail]<mailto:[e-mail]>

> >>>>>>>> https://www.ietf.org/mailman/listinfo/lsr

> >>>>>>

> >>>>

> >>> _______________________________________________

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> >>

> >

> >

>

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