Re: [spring] [OPSAWG] [Lsr] draft-tgraf-ipfix-mpls-sr-label-type

[Gyan Mishra <[e-mail]>]

Hi Thomas

Just a thought to build on what Tianran mentioned.

It almost seems as if IPFIX taking on the role of BGP-LU / PCE  centralized
controller function to to create a SR graph of the topology.  We already
have all the SR topology data in the PCE for path instantiation and
steering.

Do we also really need the data replicated into IPFIX.

The PCE may also be able to do fault isolation and troubleshooting as it
has the topology of the entire SR domain.

Something to consider.  Also gathering flat bits and pieces of information
is  not the same as what is being fed by BGP-LS into the PCE.  So am
wondering what value this will provide with the flat construction of the
network graph.

Gyan

On Sun, Aug 16, 2020 at 11:05 PM Tianran Zhou <[e-mail]>
wrote:

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> Hi Thomas,
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> I think questions from both Ketan and Gyan on the IE usage are very
> important. The value should be described clearly in the draft. So that
> people now how to implement and use them.
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>
> Here your replay to Ketan on the mplsTopLabelType is clear to me. You want
> to account the traffic with different IGP distribution, to see if your
> network runs correct.
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> The SrSidType seems more complex.
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> “Since it describes that a particular adjacency is chosen to forward the
> packet instead of a prefix. If IE 89, ForwardingStatus is drop, we
> understand that result of that decision lead to the drop and this enables
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> to narrow down forwarding issues in segment routing networks more
> efficiently and quickly.”
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> Could you please make this use case more clear joint with IE89?
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> And this case want to justify the value of Adjacency SID. Is there any
> other use cases for accounting other sid types?
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> Thanks,
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> Tianran
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> *From:* OPSAWG [mailto:[e-mail]]
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> *On Behalf Of*[e-mail]
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> *Sent:* Saturday, August 15, 2020 2:01 PM
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> *To:* [e-mail]; [e-mail]
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> *Cc:* [e-mail]; [e-mail]; [e-mail]
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> *Subject:* Re: [OPSAWG] [Lsr] draft-tgraf-ipfix-mpls-sr-label-type
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> Hi Ketan,
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> Ø
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> This helps identification of specific SR-MPLS segment types as well as
> differentiating them from LDP, RSVP-TE, etc.
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> To be precise, the existing MPLS Label Type identifier differentiates from
> LDP, RSVP-TE. Not the new SrSidType IPFIX IE being proposed.
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> Ø
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> What value is provided for IPFIX analysis if the SR Prefix SID was being
> signalled via OSPF or ISIS?
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> It is important to distinguish between intend and result.
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> If you migrate from one label distribution protocol to another, a network
> operator want's to understand if the data plane is still forwarding packets
> with
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> the label distribution protocol which needs to be removed or not. IE46
> enables that by looking at the result of the forwarded traffic and not at
> the intend. RFC 8661 section 3,
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> https://tools.ietf.org/html/rfc8661#section-3,
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> describes the context.
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> Ø
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> What value is provided for IPFIX analysis if it was a Adjacency SID or a
> LAN Adjacency SID?
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> Quote from RFC8402. "Segment Routing (SR) leverages the source routing
> paradigm". Means that not the routing protocol does all the forwarding
> decisions,
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> the node can change the forwarding by pushing additional labels.. With
> IPFIX SrSidType we are able to cover this dimension in IPFIX. Enabling to
> analyze the result of this decision. The example with " Adjacency SID or a
> LAN Adjacency SID" is not very useful
>
> because the difference of the two is the topology among the adjacency. If
> you compare " Adjacency SID with Prefix SID", that makes much more sense.
> Since it describes that a particular adjacency is chosen to forward the
> packet instead of a prefix. If IE 89,
>
> ForwardingStatus is drop, we understand that result of that decision lead
> to the drop and this enables to narrow down forwarding issues in segment
> routing networks more efficiently and quickly.
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> Ø
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> am asking for WG to weigh the implementation complexities
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> For the WG and me, I would be important if you can describe more detailed
> what you mean with
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> implementation complexities. I would like to have a better understanding
> where your fear is coming from. I would appreciate if you could
> differentiate between
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> MPLS Label Type identifier, IE46, from which label protocol the label was
> coming from and SrSidType which SID type was used..
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> Best wishes
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> Thomas
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> *From:* Ketan Talaulikar (ketant) <[e-mail]>
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> *Sent:* Saturday, August 15, 2020 7:09 AM
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> *To:* Graf Thomas, INI-NET-DCF <[e-mail]>;
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> [e-mail]
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> *Cc:* [e-mail];
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> [e-mail]; [e-mail]
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> *Subject:* RE: [Lsr] draft-tgraf-ipfix-mpls-sr-label-type
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> Hi Thomas,
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> I should have been more clear in my email.
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> The proposal/suggestion is to add the following to the IPFIX MPLS Label
> type identifier registry:
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> -
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> SR Prefix SID
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> -
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> SR Adjacency SID
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> -
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> SR Binding SID
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> -
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> SR BGP Peering SID
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> -
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> … and so on
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> This helps identification of specific SR-MPLS segment types as well as
> differentiating them from LDP, RSVP-TE, etc.
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> And my questions were:
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> 1)
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> What value is provided for IPFIX analysis if the SR Prefix SID was being
> signalled via OSPF or ISIS?
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> 2)
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> What value is provided for IPFIX analysis if it was a Adjacency SID or a
> LAN Adjacency SID?
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> I am asking for WG to weigh the implementation complexities and overheads
> with the proposed details of SR-MPLS segments in IPFIX against the benefit
> (if any) that they provide for the
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> flow analysis and monitoring.
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> Thanks,
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> Ketan
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> *From:* [e-mail] <[e-mail]>
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> *Sent:* 15 August 2020 09:40
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> *To:* Ketan Talaulikar (ketant) <[e-mail]>;
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> [e-mail]
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> *Cc:* [e-mail];
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> [e-mail]; [e-mail]
>
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> *Subject:* RE: [Lsr] draft-tgraf-ipfix-mpls-sr-label-type
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> Hi Ketan,
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> Thank you very much for the review and feedback.
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> Ø
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> What or how much value be there on determining whether a SR Prefix SID was
> signalled/programmed on a node via OSPFv2/OSPFv3/ISIS – what matters and is
> more important is that
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> it is a Prefix SID. Hardly any deployments would be running multiple
> protocols and learning the same prefix from different IGPs.
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> As Jeff already pointed out. Multiple IGP labelling protocols are used  in
> networks when migrations are ongoing. Usually in a life cycle. Migrating
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> from LDP to OSPFv2/OSPFv3/ISIS SR TLV. This is/was also the case at
> Swisscom when we first discovered this shortcoming in vendor
> implementations. The key point here, with these additional IPFIX MPLS Label
> Type identifiers we enable the possibility to verify
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> the label protocol migration without taking the label value into the
> consideration.
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> Ø
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> IPFIX may be picking this information from a FIB in some implementation
> where the protocol does not matter and this information is not available
> therein.
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> I am not sure if you have seen the presentation in IETF 108 at OPSAWG and
> SPRING.
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> https://www.ietf.org/proceedings/108/slides/slides-108-opsawg-export-of-mpls-sr-label-type-information-in-ipfix-00.pdf
> <https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ietf.org%2Fproceedings%2F108%2Fslides%2Fslides-108-opsawg-export-of-mpls-sr-label-type-information-in-ipfix-00.pdf&data=02%7C01%7CThomas.Graf%40swisscom.com%7Cdef70609f2d843c24ad908d840d954dc%7C364e5b87c1c7420d9beec35d19b557a1%7C1%7C0%7C637330649465806010&sdata=rYZxsfoyTc2ZAqbqf2DLfiBhiRQyNcfGS8tvzeTGda0%3D&reserved=0>
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> Slide 2 shows Cisco as example vendor which implemented IE 46, MPLS Label
> Type identifier. There is an open ddts where vendor feasibility has
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> been clarified. Ping me off the list when you like to have more details.
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> I do understand your point that not all the vendors are capable to
> implement IE 46. But that’s not the point about the IPFIX IE registry.
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> The IE registry enables that an IPFIX implementation can refer to the
> right code point. With RFC 5102 the decision has been made that MPLS Label
> Type identifier
>
> make sense and can be implemented. draft-tgraf-ipfix-mpls-sr-label-type
> just extends the IE 46 registry with the Segment Routing label protocol
> code points so when OSPFv2/OSPFv3/ISIS SR TLV is used, and IE 46 is
> supported, the IPFIX implementation can point
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> to the right code point.
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> Ø
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> On some nodes, the same Prefix SID may be learnt via both BGP and IGP –
> what would we use/show?
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> In this case the IE 46 shows the label protocol which was used to program
> the FIB.
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> Ø
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> For that table proposal, it is very difficult and in some cases not
> possible to different between Prefix and Node and Anycast SID. Many of
> these types are control plane elements
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> and we can be sure more get added.
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> I fully agree. As a network operator its still hard to understand the
> architecture and constraints within a router. When monitoring capabilities
> are discussed
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> at IETF, this is the usual topic. What is possible, what make sense. By
> purpose, all available SID types are listed in the draft. This with the aim
> to start the discussion in the working groups what is possible what makes
> sense. I would be interested to get
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> your and also Jeff's feedback.
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> In above mentioned slides I described how TI-LFA application would benefit
> of visibility in the FIB by showing where Adj-SID was used. This should be
> a simple
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> example why it make sense not only to look at which label protocol was
> used to forward a particular packet, but also which SID type to further
> understand the intend why this label is being pushed.
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> I hope this makes all sense. Looking forward for reply.
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> Best wishes
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> Thomas
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> *From:* Ketan Talaulikar (ketant) <[e-mail]>
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> *Sent:* Friday, August 14, 2020 7:35 PM
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> *To:* Graf Thomas, INI-NET-DCF <[e-mail]>;
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> [e-mail]
>
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> *Cc:* [e-mail]; SPRING WG <[e-mail]>
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> *Subject:* RE: [Lsr] draft-tgraf-ipfix-mpls-sr-label-type
>
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> < also copying Spring WG for their review/inputs >
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> Hi Thomas/All,
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> I have reviewed the draft and would like to share a different perspective.
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> What or how much value be there on determining whether a SR Prefix SID was
> signalled/programmed on a node via OSPFv2/OSPFv3/ISIS – what matters and is
> more important is that it is a
>
> Prefix SID. Hardly any deployments would be running multiple protocols and
> learning the same prefix from different IGPs. IPFIX may be picking this
> information from a FIB in some implementation where the protocol does not
> matter and this information is not
>
> available therein.
>
>
>
>
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> On some nodes, the same Prefix SID may be learnt via both BGP and IGP –
> what would we use/show?
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> I would recommend using SR Prefix SID, SR Adjacency SID, SR Binding SID,
> SR BGP Peering SID and so on … for the MPLS Label Type.
>
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>
>
>
> This also takes away the need for the second table that is being proposed
> to a large extent. For that table proposal, it is very difficult and in
> some cases not possible to different
>
> between Prefix and Node and Anycast SID. Many of these types are control
> plane elements and we can be sure more get added. Is there really much
> value in differentiation between say an Adjacency SID and LAN Adjacency SID?
>
>
>
>
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> Could we evaluate the implementation overhead and complexity of this level
> of categorization/information in IPFIX against their value in flow analysis
> to perhaps consider a middle ground?
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> Thanks,
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> Ketan
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> *From:* Lsr <[e-mail]>
>
> *On Behalf Of *[e-mail]
>
>
> *Sent:* 31 July 2020 20:52
>
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> *To:* [e-mail]
>
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> *Cc:* [e-mail]
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> *Subject:* Re: [Lsr] draft-tgraf-ipfix-mpls-sr-label-type
>
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> Hi Hannes,
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> Thanks a lot for the feedback. Yes, makes completely sense. Will take it
> for the next update...
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> Best Wishes
>
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> Thomas
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> *From:* Hannes Gredler <[e-mail]>
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> *Sent:* Wednesday, July 29, 2020 9:31 AM
>
>
> *To:* Graf Thomas, INI-NET-DCF <[e-mail]>
>
>
> *Cc:* [e-mail]
>
>
> *Subject:* Re: [Lsr] draft-tgraf-ipfix-mpls-sr-label-type
>
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> Thomas,
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> I have one comment/suggestion to Paragraph 4 (IANA Considerations).
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> Please add also a code point for BGP Prefix-SID - it’s quite popular in DC
> deployments.
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> https://tools..ietf.org/html/rfc8669
> <https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf.org%2Fhtml%2Frfc8669&data=02%7C01%7CThomas.Graf%40swisscom.com%7Cdef70609f2d843c24ad908d840d954dc%7C364e5b87c1c7420d9beec35d19b557a1%7C1%7C0%7C637330649465806010&sdata=WiW65MqkVXM5BOqJ7VxFPj14s9RynoBTjgzU%2Fhu%2FKOk%3D&reserved=0>
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> thanks,
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> /hannes
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> On 28.07.2020, at 10:11,
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> [e-mail] wrote:
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> Dear lsr,
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> I presented the following draft
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> Export of MPLS Segment Routing Label Type Information in IP Flow
> Information Export (IPFIX)
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> https://tools.ietf.org/html/draft-tgraf-ipfix-mpls-sr-label-type-04
> <https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf.org%2Fhtml%2Fdraft-tgraf-ipfix-mpls-sr-label-type-04&data=02%7C01%7CThomas.Graf%40swisscom.com%7Cdef70609f2d843c24ad908d840d954dc%7C364e5b87c1c7420d9beec35d19b557a1%7C1%7C0%7C637330649465815966&sdata=1DIvkRCu5tKMVSooUnsF%2B5R1h12rVOkbYyYzqvKSgV4%3D&reserved=0>
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> at the spring working group at IETF 108 yesterday
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> https://www.ietf.org/proceedings/108/slides/slides-108-spring-ip-flow-information-export-ipfix-00.pdf
> <https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ietf.org%2Fproceedings%2F108%2Fslides%2Fslides-108-spring-ip-flow-information-export-ipfix-00.pdf&data=02%7C01%7CThomas.Graf%40swisscom.com%7Cdef70609f2d843c24ad908d840d954dc%7C364e5b87c1c7420d9beec35d19b557a1%7C1%7C0%7C637330649465815966&sdata=OM8BhFC%2FQJL3h%2FjqQPULt1c5SBTaz6yp%2Bj6i0QOjJJQ%3D&reserved=0>
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> and today at OPSAWG where I call for adoption.
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> This draft adds additional segment routing code points for in the IANA
> IPFIX registry for IS-IS, OPSFv2 and OPSF v3 and segment routing SID types
> to gain further insights
>
> into the MPLS-SR forwarding-plane.
>
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> I have been asked to not only gather feedback from spring and opsawg but
> also from lsr and mpls working groups since these code points are related
> to link state routing
>
> protocols and mpls data plane.
>
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> I am looking forward to your feedback and input.
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> Best Wishes
>
>
>
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>
>
> Thomas Graf
>
>
>
>
> _______________________________________________
>
>
> Lsr mailing list
>
>
> [e-mail]
>
>
> https://www.ietf.org/mailman/listinfo/lsr
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> _______________________________________________
>
> OPSAWG mailing list
>
> [e-mail]
>
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>
> --

<http://www.verizon.com/>

*Gyan Mishra*

*Network Solutions A**rchitect *



*M 301 502-134713101 Columbia Pike *Silver Spring, MD