[Lsr] Summary of WGLC discussion about draft-ietf-isis-te-app-06.txt and draft-ietf-ospf-te-link-attr-reuse-07.txt

[<[e-mail]>]

Dear all

As there is no more exchange about the two mentioned drafts since 3 weeks, I'll try to summarize the exchange and
the requested modifications.

The drafts proposed to extended IS-IS respectively OSPF to advertise new TE parameters to overcome 2 issues:
 1 - Topology incongruence between the IGP and TE
 2 - Provide different parameters per application

For the first point, topology incongruence is not due to the protocol itself but to the fact that an operator
may activate or not TE information on all links of its network. Indeed, RFC3630 and RFC5305 precise that TE
information are Optionals.

However, in both drafts, the term RECOMMENDED is used, which IMHO not solve the problem. An operator keeps the choice
to activate or not this new TE information leading again to an incongruence network topology. At least, wording
need to be change to MUST or MANDATORY. But, why not just change the wording of RFC3630 and RFC5305 ?

In addition, no operator express explicitly that their are concern by topology incongruence.

 => Introduction sections should be improved to better justify why we need to modify TE link advertisement
 => Wording must be revise to avoid incongruence topology

For the second point, TE information are related to a link not an application even if at the origin, RFC3630 and RFC5305
were design for RSVP-TE. It is not mention in the RFCs that they could not be applicable to other protocol / application.

If the idea, in liaison to first point, it to determine is an application / protocol is enable / disable on a given link,
even if their have been not selected, drafts draft-hegde-ospf-advertising-te-protocols-01.txt and
draft-hegde-isis-advertising-te-protocols-03.txt are largely sufficient as it is not necessary to duplicate link TE
information. In addition, Router Information already provides indication on the support of SR by this router (presence
of SRGB) where all IGP links are de-facto SR enable.

Then, GMPLS specific attributes are not taken into account in these drafts.

 => GMPLS must be considered as another application and specific GMPLS attribute must be part of the drafts
 => or standardised only SABML / UDABML flags without duplicating TE information

Network operational transition issues are poorly address in these drafts. Indeed, router upgrade
take time in large scale network (several weeks even several months) leading cohabitation of the 2 systems which
introduce a large degree of complexity for operators for network management.

 => Improve migration section to help operator during the transition phase

And finally, if we go a bit further, dealing with SDN, all these new TE information need to be learnt by and SDN
controller e.g. a PCE, which naturally conduct to use BGP-LS for this purpose. However, recent discussion in idr WG
mention that there is already too many attributes that have been standardised dealing with problem with the maximum
size of BGP message. These new TE information will also certainly appear as duplicate regarding RFC7752 and RFC8571.

So, I would ask authors of both drafts to know how they intend to manage this problem ?
For us, if these new TE information could not be learnt through BGP-LS, there is no interest to use them.

Regards

Olivier



  


_________________________________________________________________________________________________________________________

Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci.

This message and its attachments may contain confidential or privileged information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and delete this message and its attachments.
As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified.
Thank you.