Re: [CCAMP] [OSPF] draft-giacalone-ospf-te-express-path-01

[Acee Lindem <[e-mail]>]

Hi Alia,
I guess I agree with Lou - heretofore, we've done TE requirements in the MPLS/CCAMP WGs and the TE encodings in the IGP WGs. I think we should give the decision explicit consideration before we branch off and do TE for application X independently. Additionally, if we do decide to split this off independently, an E-mail to the list saying there is no overlap is not sufficient to move forward. At a minimum, I believe we need to:

   1. Explicitly document this alternate applicability and relationship to existing TE in the draft.
   2. Determine whether any sub-TLVs can be shared (my opinion was consistent with yours that there are not due to differences in requirements and measurement). 
   3. Assure the sub-TLVs are appropriately named to avoid confusion between the latency applications. 
  
Thanks,
Acee 
On Jun 21, 2011, at 2:08 PM, Alia Atlas wrote:

> Hi Acee,
> 
> John Drake and I did take a look at the draft mentioned in CCAMP.  It
> had a large number of requirements and extensions to
> a number of different protocols.  There is one sub-TLV (latency) that
> appears the same - but the expectations
> as to averaging vs. instantaneous were different.
> 
> The OSPF TE Express Path work is fairly self-contained and doesn't
> specify in exact detail how the information
> for the sub-TLVs is measured or obtained.  I think it could be used
> for multiple purposes.
> 
> Alia
> 
> On Tue, Jun 21, 2011 at 12:49 PM, Acee Lindem <[e-mail]> wrote:
>> Hi Spencer (CCAMP copied as well),
>> 
>> Here is a link for everyone's convenience:
>> 
>> http://www.ietf.org/id/draft-giacalone-ospf-te-express-path-01.txt
>> 
>> At IETF 80, there were questions about overlap with other CCAMP drafts containing interface delay metrics and proposals for new TE sub-TLVs. Have you or your co-authors, done looked at how your draft is positioned versus these other drafts? While these applications have differing goals, the CCAMP/OSPF chairs requested that this analysis be done.
>> 
>> http://www.ietf.org/id/draft-wang-ccamp-latency-te-metric-03.txt
>> 
>> We would like to avoid having exactly the same information advertised in two different link Sub-TLVs. I'd hope we could agree on common units.
>> 
>> Thanks,
>> Acee
>> 
>> On Jun 20, 2011, at 4:30 PM, Spencer Giacalone wrote:
>> 
>>> Hello everyone,
>>> 
>>> As you may have noticed, another version of the OSPF TE Express Path
>>> draft has been posted. We made a number of changes based on feedback
>>> from IETF 80. We invite your comments and suggestions. The main
>>> changes include:
>>> 
>>> -We have consolidated some sub-TLVs for efficiency. There are no
>>> longer nominal and anomalous sub-TLVs for delay and loss. The
>>> functionality for signaling steady state verses abnormal performance
>>> for these parameters have been moved into two sub-TLVs (where we used
>>> to have four).
>>> 
>>> -In order to advertise both normal and abnormal network performance
>>> state in consolidated sub-TLVs, a bit, called the anomalous (A) but
>>> has been added to certain sub-TLVs. The A bit is set when the measured
>>> value of a parameter exceeds a configured maximum threshold. The A bit
>>> is cleared when the measured value falls below its configured reuse
>>> threshold. If the A bit is clear, the sub-TLV represents steady state
>>> link performance.
>>> 
>>> -We changed the encodings of certain variables from floating point to
>>> fixed point. This change permits the addition of the A bit (when
>>> necessary), it allows bit-space reservations to be made, and it
>>> permits a common TLV format across the bulk of the TLVs in the draft.
>>> In addition, the new encodings address concerns about granularity and
>>> interoperability.
>>> 
>>> -We added sub-TLVs for Residual Bandwidth and Available Bandwidth.
>>> Residual bandwidth is defined as the Maximum Bandwidth [RFC3630] minus
>>> the bandwidth currently allocated to RSVP-TE LSPs. Available bandwidth
>>> is defined to be residual bandwidth minus the measured bandwidth used
>>> for the actual forwarding of non-RSVP-TE LSP packets.
>>> 
>>> -Various other modifications were made across the draft. These
>>> include, but are not limited to, the abstract, the introduction, the
>>> thresholding specifications, and a number of field descriptions.
>>> 
>>> -Last, but certainly not least, Stefano Providi has joined the draft
>>> 
>>> We look forward to hearing your comments and concerns.
>>> 
>>> Thanks,
>>> 
>>> Spencer, Alia, Dave, John, Stefano
>>> _______________________________________________
>>> OSPF mailing list
>>> [e-mail]
>>> https://www.ietf.org/mailman/listinfo/ospf
>> 
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