Re: [Lsr] Working Group Last Call for "OSPF Link Traffic Engineering (TE) Attribute Reuse" - draft-ietf-ospf-te-link-attr-reuse-07.txt

Hi Olivier,

On 12/04/2019 16:26 , olivier.dugeon@orange.com wrote:
> Hello Peter,
>
>
> Le 12/04/2019 à 15:27, Peter Psenak a écrit :
>> Hi Oliver,
>>
>> There are two major purposes served by the drafts:
>>
>> 1)Support of incongruent topologies for different applications
> Don't understand. What do you mean ?

RFC3630 allows the traffic engineering topology to be incongruent with 
the regular routing topology. This means that the RSVP TE topology can 
only be a subset of the regular routing topology. If there is a need to 
advertise some link attribute for the purpose of the other application, 
the link would become part of the RSVP TE topology, something that may 
not be desired.

>>
>> 2)Advertisement of application specific values even on links that are in
>> use by multiple applications
> Hum. Do you think it makes sense to announce different TE metric for the
> same link for different applications ? e.g. 10 ms delay for RSVP-TE, 20
> ms for SR, 15 ms for LFA and 5 ms for Flex -Algo ? The link has a fix
> delay propagation whatever the application.
>
> If the goal is to dedicated link per application, Resource Class/Color
> attribute could be used. If you would advertised different metric per
> CoS, then you need to dedicated metric per CoS like the unreserved
> bandwidth.

The goal is the allow the link to be used by multiple applications, but 
be advertised with application specific attributes.

>>
>> These issues are clearly articulated in the Introductions of both
>> drafts. LSR WG acknowledged them a while back and decided to address
>> them.
>>
>> Issue #1 has already had a significant impact on early deployments of
>> SRTE in networks where there is partial deployment of SR in the presence
>> of RSVP-TE.
> Can you point me a concrete and detail example of the problem ? With a
> PCE, there is no problem to manage both RSVP-TE and SR-TE in the same
> network. And again, as already mention, if the problem come from
> bandwidth reservation, the draft will not solve the issue.

there is no way to advertise the link for the purpose of the SR-TE, 
without it becoming the part of the RSVP-TE using existing 
advertisements. Similarly applicable in the context of any other 
application.

>>
>> Issue #2 will be seen in deployments where Flex-Algo and SRTE (or
>> RSVP-TE) are also present. Early implementers of Flex-Algo can attest to
>> this.
> Again, I don't see the problem. Can you explain in detail ? I already
> implement SR in OSPF, starting playing with TE, and there is no problem
> to get TE information from OSPF to tune some Segment Path. If it is an
> implementation issue, it is not a new RFC that will solve the problem.

we are not trying to solve the implementation issue. We are solving the 
protocol issue. Both protocols have defined many link attributes for the 
purpose of the RSVP-TE. Some of these are usable outside of the RSVP TE 
and we are extending the protocols to support that.

Please read the discussion on the mailing list that happened prior to 
the WG adoption of these drafts.

>>
>> It is simply not possible to address these issues with the existing
>> single set of application independent advertisements.
> Why ? Again, explain in detail. I don't see a real use case that could
> not be address with standard TE attributes.

please see above.

thanks,
Peter

>>
>> The solutions we provide in both drafts allow to share the link
>> attributes between application as well as keep them separate if that is
>> what is required.
>>
>> thanks,
>> Peter
>
> Regards
>
> Olivier
>
>>
>> On 11/04/2019 19:43 , olivier.dugeon@orange.com wrote:
>>> Hi,
>>>
>>> I'm not in favour of this draft.
>>>
>>> As already mention, I don't see the interest to duplicate TE attributes
>>> in new Extended Link Opaque LSA. For me, it is only a matter of
>>> implementation to look at various place in the OSPF TE Database to take
>>> Traffic Engineering information.
>>>
>>> From an operator perspective, it is already hard to manage TE attribute
>>> and I'm pretty sure that we could not ask network management team to
>>> maintain 2 systems for certainly a long period of time as many TE
>>> attributes remains in the standard Opaque LSA Traffic Engineering.
>>>
>>> Regards
>>>
>>> Olivier
>>>
>>>
>>> Le 11/04/2019 à 18:11, Acee Lindem (acee) a écrit :
>>>>
>>>>  LSR Working Group,
>>>>
>>>>
>>>>
>>>> This begins a two week  WG last call for the subject document. Please
>>>> enter your support or objection to the document before 12:00 AM (EDT)
>>>> on Friday, April 27^th , 2019.
>>>>
>>>>
>>>>
>>>> Thanks,
>>>> Acee
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
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>>>> Lsr@ietf.org
>>>> https://www.ietf.org/mailman/listinfo/lsr
>>>
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>
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>
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