Dear Olivier, all Please see inline
El 22/09/2011 18:22, Olivier Dugeon escribió:
IMHO, I think that it is missing something in the different proposal to compute inter-domain tunnel. This is related to the TED. Indeed, there is no proposal to collect suitable information that could help the PCE (in BRPC or in H-PCE) to select (compute) the AS path, and so select the better (regarding the request) peer PCE. Such information, like TE of the peering point between two ASs, are mandatory if we want to select alternate AS path than the one announced by BGP. If such mandatory information are out of scope of PCE WG, I'm afraid that, for me, their is no difference between the BRPC and H-PCE, instead on how PCE are cooperate. The result will be the same in term of path computation.
As you may know, the issue of TED management and, in particular, TED management in the context of multi-domain path computation is raised regularly (including myself!) and no consensus seems to be reached.
To some extent, I understand the (architectural and functional) idea of keeping TED management somehow decoupled from the actual path computation function, as it is done in the context of single domain path computation, where the way the PCE obtains the TED is out of the scope (and in some sense, orthogonal).
However, I believe that in some cases both functions (path computation and TED management) are slightly coupled (border node identification, endpoint localization and topology aggregation for domain sequence selection, to name a few in which an IGP-based TED may not be sufficient). For what is worth, an approach that we proposed in the past (as well as other implementers) has been to use PCNtf with embedded OSPF-TE LSUs / LSAs (or XML files or any other encoding) TED "slices".
This approach -- completely non-standard -- can be used for both wrapping and forwarding InterAS links [RFC5392] -- which, I agree with you, seems relevant for a more efficient selection of the AS path and would seem to address your requirement. This is briefly mentioned in Fatai's and Dan's draft-zhang-pcep-hpce -- the same approach can be used to wrap any other topological information. We did in a research project, including "virtual links or nodes" for topology aggregation (i.e. full-mesh) in H-PCE. In private communications I got the feeling that this is somehow "frowned upon" ;) and that AS peering and connectivity is managed at another (i.e. managed) level.
Is this make sense for the PCE WG and if yes, do you think it is suitable to propose a draft for that purpose (we have some ideas for that here) ?
I am not against such a proposal, since it is easier and simpler to "stick to a common way of doing things", although it is difficult to decide and I would understand the WG position against it, if it was the case. Nonetheless I, for one, would be interested in hearing your ideas :)
Thanks Ramon -- Ramon Casellas, Ph.D. Research Associate - Optical Networking Area -- http://wikiona.cttc.es CTTC - Centre Tecnològic de Telecomunicacions de Catalunya, PMT Ed B4 Av. Carl Friedrich Gauss, 7 - 08860 Castelldefels (Barcelona) - Spain Tel.: +34 93 645 29 00 -- Fax. +34 93 645 29 01 _______________________________________________ Pce mailing list Pce@ietf.org https://www.ietf.org/mailman/listinfo/pce
