Re: [OSPF] OSPFv2 SR draft

[Acee Lindem <[e-mail]>]

Aren’t the text changes restricted to draft-ietf-spring-segment-routing? 

Acee 
> On Sep 29, 2016, at 12:00 PM, Chris Bowers <[e-mail]> wrote:
> 
> I would like to see actual textual updates in the form of new revisions for the clarifications that have been proposed for both draft-ietf-ospf-segment-routing-extensions and draft-ietf-spring-segment-routing so that we know exactly what text we are agreeing on.
> 
> Chris
> 
> 
> -----Original Message-----
> From: Acee Lindem (acee) [mailto:[e-mail]] 
> Sent: Thursday, September 29, 2016 10:50 AM
> To: Chris Bowers <[e-mail]>; Les Ginsberg (ginsberg) <[e-mail]>; Peter Psenak (ppsenak) <[e-mail]>; OSPF List <[e-mail]>
> Subject: Re: [OSPF] OSPFv2 SR draft
> 
> Speaking as WG Co-Chair:
> 
> Hi Chris, Les, Peter,
> 
> So, is there anything preventing us from requesting publication of the
> OSPFv2 Segment Routing draft?
> 
> Thanks,
> Acee
> 
> 
> On 8/25/16, 11:00 AM, "OSPF on behalf of Chris Bowers"
> <[e-mail] on behalf of [e-mail]> wrote:
> 
>> Les and Peter,
>> 
>> I have also been pursuing the approach you suggest.
>> 
>> The following request to clarify draft-ietf-spring-segment-routing-09 
>> on this topic was sent on  Aug. 3rd.
>> 
>> https://www.ietf.org/mail-archive/web/spring/current/msg02273.html
>> 
>> Hopefully, we can get closure on these clarifications soon.
>> 
>> Thanks,
>> Chris
>> 
>> 
>> -----Original Message-----
>> From: Les Ginsberg (ginsberg) [mailto:[e-mail]]
>> Sent: Thursday, August 25, 2016 9:32 AM
>> To: Peter Psenak (ppsenak) <[e-mail]>; Chris Bowers 
>> <[e-mail]>; OSPF List <[e-mail]>
>> Subject: RE: [OSPF] OSPFv2 SR draft
>> 
>> Chris/Peter -
>> 
>>> -----Original Message-----
>>> From: OSPF [mailto:[e-mail]] On Behalf Of Peter Psenak
>>> (ppsenak)
>>> Sent: Thursday, August 25, 2016 1:45 AM
>>> To: Chris Bowers; OSPF List
>>> Subject: Re: [OSPF] OSPFv2 SR draft
>>> 
>>> Hi Chris,
>>> 
>>> On 24/08/16 20:31 , Chris Bowers wrote:
>>>> Peter,
>>>> 
>>>> The text that you propose corresponds to part of the text that I 
>>>> proposed,
>>> and it seems good to me.
>>>> 
>>>> However, the last sentence of the text that I proposed in not
>>> addressed.
>>>> ------
>>>> If router B does not advertise the
>>>> SR-Algorithm TLV for algorithm X, then other routers should not 
>>>> forward traffic destined for a prefix-SID for algorithm X 
>>>> advertised by some router D using a path that would require router 
>>>> B to forward traffic using algorithm X.
>>>> ------
>>>> Is this an oversight?
>>> 
>>> not that I disagree with the statement that you want to add.
>>> 
>>> The question is whether that belongs to the IGP SR draft, or whether 
>>> that should be specified in a different draft.
>>> 
>>> There is already some text regarding the forwarding for a SR 
>>> algorithm in draft-ietf-spring-segment-routing section 3.2.1., which 
>>> may not be aligned with what you have in mind:
>>> 
>>>   "The ingress node of an SR domain validates that the path to a 
>>> prefix,
>>>    advertised with a given algorithm, includes nodes all supporting the
>>>    advertised algorithm.  In other words, when computing paths for a
>>>    given algorithm, the transit nodes MUST compute the algorithm X on
>>>    the IGP topology, regardless of the support of the algorithm X by 
>>> the
>>>    nodes in that topology.  As a consequence, if a node on the path 
>>> does
>>>    not support algorithm X, the IGP-Prefix segment will be interrupted
>>>    and will drop packet on that node.  It's the responsibility of the
>>>    ingress node using a segment to check that all downstream nodes
>>>    support the algorithm of the segment."
>>> 
>>> Maybe we should add/modify the text in  
>>> draft-ietf-spring-segment-routing section 3.2.1, rather then adding 
>>> anything to the OSPF/ISIS SR drafts.
>>> 
>> [Les:] I strongly agree with this approach. If one wants to understand 
>> how the MPLS dataplane works with SR then the following documents are
>> relevant:
>> 
>> https://www.ietf.org/id/draft-ietf-spring-segment-routing-09.txt
>> https://www.ietf.org/id/draft-ietf-spring-segment-routing-mpls-05.txt
>> https://www.ietf.org/id/draft-ietf-spring-segment-routing-ldp-interop-0
>> 4.t
>> xt
>> 
>> References to these documents can be included in the IGP drafts - but 
>> we should not try to repurpose the IGP drafts to cover material which 
>> is covered far more completely in the above drafts.
>> 
>> If you feel there is something which needs to be added/revised to any 
>> of the above drafts to more accurately explain algorithm specific 
>> forwarding please make the comment in the context of one of those drafts.
>> 
>>  Les
>> 
>>> thanks,
>>> Peter
>>> 
>>>> 
>>>> Thanks,
>>>> Chris
>>>> 
>>>> 
>>>> -----Original Message-----
>>>> From: Peter Psenak [mailto:[e-mail]]
>>>> Sent: Monday, August 22, 2016 2:32 AM
>>>> To: Chris Bowers <[e-mail]>; OSPF List <[e-mail]>
>>>> Subject: Re: [OSPF] OSPFv2 SR draft
>>>> 
>>>> Chris,
>>>> 
>>>> what about this to be added in the Section 3.1:
>>>> 
>>>> 
>>>> "A router receiving a Prefix-SID (defined in section 5) from a 
>>>> remote node
>>> and with an SR algorithm value that such remote node has not  
>>> advertised in the SR-Algorithm sub-TLV MUST ignore the Prefix-SID 
>>> sub-TLV."
>>>> 
>>>> thanks,
>>>> Peter
>>>> 
>>>> 
>>>> On 19/08/16 23:33 , Chris Bowers wrote:
>>>>> Peter,
>>>>> 
>>>>> Please share the updated text that you plan to use with the WG, 
>>>>> since this
>>> is a reasonably significant clarification.
>>>>> 
>>>>> Thanks,
>>>>> Chris
>>>>> 
>>>>> -----Original Message-----
>>>>> From: Peter Psenak [mailto:[e-mail]]
>>>>> Sent: Tuesday, August 16, 2016 10:02 AM
>>>>> To: Chris Bowers <[e-mail]>; OSPF List <[e-mail]>
>>>>> Subject: Re: [OSPF] OSPFv2 SR draft
>>>>> 
>>>>> Hi Chris,
>>>>> 
>>>>> I'll update the draft along those lines.
>>>>> 
>>>>> thanks,
>>>>> Peter
>>>>> 
>>>>> 
>>>>> On 16/08/16 16:02 , Chris Bowers wrote:
>>>>>> Peter,
>>>>>> 
>>>>>> I suggest changing the paragraph to read as below to make this
>>> clearer.
>>>>>> 
>>>>>> =====
>>>>>>      The SR-Algorithm Sub-TLV is optional.  It MAY only be
>>> advertised once
>>>>>>      in the Router Information Opaque LSA.  If the SID/Label 
>>>>>> Range
>>> TLV, as
>>>>>>      defined in Section 3.2, is advertised, then the 
>>>>>> SR-Algorithm
>>> TLV MUST
>>>>>>      also be advertised.  If a router C advertises a Prefix-SID 
>>>>>> sub-TLV for
>>> algorithm X
>>>>>>      but does not advertise the SR-Algorithm Sub-TLV with 
>>>>>> algorithm X,
>>> then
>>>>>>      a router receiving that advertisement MUST ignore the
>>> Prefix-SID
>>>>>>      advertisement from router C.  If router B does not 
>>>>>> advertise
>>> the
>>>>>>      SR-Algorithm TLV for algorithm X, then other routers should
>>> not
>>>>>>      forward traffic destined for a prefix-SID for algorithm X
>>> advertised by
>>>>>>      some router D using a path that would require router B to 
>>>>>> forward
>>> traffic using
>>>>>>      algorithm X.
>>>>>> =====
>>>>>> 
>>>>>> Thanks,
>>>>>> Chris
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> -----Original Message-----
>>>>>> From: Peter Psenak [mailto:[e-mail]]
>>>>>> Sent: Monday, August 15, 2016 6:40 AM
>>>>>> To: Chris Bowers <[e-mail]>; OSPF List <[e-mail]>
>>>>>> Subject: Re: [OSPF] OSPFv2 SR draft
>>>>>> 
>>>>>> Hi Chris,
>>>>>> 
>>>>>> sorry for the delay, I was on PTO during last two weeks.
>>>>>> Please see inline:
>>>>>> 
>>>>>> On 03/08/16 16:45 , Chris Bowers wrote:
>>>>>>> Peter,
>>>>>>> 
>>>>>>> Taking a looking at the whole paragraph into this sentence was 
>>>>>>> added, I am not sure how to interpret it.
>>>>>>> 
>>>>>>>       The SR-Algorithm Sub-TLV is optional.  It MAY only be 
>>>>>>> advertised
>>> once
>>>>>>>       in the Router Information Opaque LSA.  If the SID/Label 
>>>>>>> Range TLV,
>>> as
>>>>>>>       defined in Section 3.2, is advertised, then the 
>>>>>>> SR-Algorithm TLV
>>> MUST
>>>>>>>       also be advertised.  If the SR-Algorithm TLV is not
>>> advertised by the
>>>>>>>       node, such node is considered as not being segment 
>>>>>>> routing
>>> capable.
>>>>>>> 
>>>>>>> Is this sentence intended to imply that if a router does not 
>>>>>>> advertise the SR-Algorithm TLV including algorithm X, then any 
>>>>>>> prefix-SIDs for algorithm X advertised by that router will be 
>>>>>>> ignored by
>>> other routers?
>>>>>> 
>>>>>> in OSPF we do not have the SR capability TLV. We use SR-Algorithm 
>>>>>> TLV for that purpose. So if a router does not advertise the 
>>>>>> SR-Algorithm TLV for algorithm X, other routers should not send 
>>>>>> any SR traffic using SIDs that were advertised for algorithm X.
>>>>>> 
>>>>>> If the router does not advertise any SR Algorithm TLV, then the 
>>>>>> node is not SR capable and no SR traffic should be forwarded to
>>> such a node.
>>>>>> 
>>>>>> thanks,
>>>>>> Peter
>>>>>> 
>>>>>> 
>>>>>>> 
>>>>>>> If this is the intention, then it would be better to state is 
>>>>>>> more
>>> explicitly.
>>>>>>> 
>>>>>>> If not, then the intended meaning should be clarified.
>>>>>>> 
>>>>>>> Thanks,
>>>>>>> Chris
>>>>>>> 
>>>>>>> 
>>>>>>> -----Original Message-----
>>>>>>> From: OSPF [mailto:[e-mail]] On Behalf Of Peter 
>>>>>>> Psenak
>>>>>>> Sent: Friday, July 22, 2016 3:30 AM
>>>>>>> To: OSPF List <[e-mail]>
>>>>>>> Subject: [OSPF] OSPFv2 SR draft
>>>>>>> 
>>>>>>> Hi All,
>>>>>>> 
>>>>>>> following text has been added in the latest revision of the
>>>>>>> OSPFv2 SR draft, section 3.1.
>>>>>>> 
>>>>>>> "If the SR-Algorithm TLV is not advertised by node, such node is 
>>>>>>> considered as not being segment routing capable."
>>>>>>> 
>>>>>>> Please let us know if there are any concerns regarding this
>>> addition.
>>>>>>> 
>>>>>>> thanks,
>>>>>>> Peter
>>>>>>> 
>>>>>>> _______________________________________________
>>>>>>> OSPF mailing list
>>>>>>> [e-mail]
>>>>>>> https://www.ietf.org/mailman/listinfo/ospf
>>>>>>> .
>>>>>>> 
>>>>>> 
>>>>>> .
>>>>>> 
>>>>> 
>>>>> .
>>>>> 
>>>> 
>>>> .
>>>> 
>>> 
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>> 
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