Re: [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]>]

Hi Acee,

Thanks to take into account my objections to the shepherds report.

For the pointer to the code, please make now reference to Free Range Routing and not Quagga.

The link is: https://github.com/FRRouting/frr and more specifically:
 - https://github.com/FRRouting/frr/lib/if.c for the link parameters implementation per interface
 - https://github.com/FRRouting/frr/ospfd/ospf_te.c for the advertisement of link parameters in OSPF
 - https://github.com/FRRouting/frr/isisd/isis_te.c for the advertisement of link parameters in ISISRegardsOlivier

Le 24/05/2019 à 13:12, Acee Lindem (acee) a écrit :
> Hi Olivier, 
> I think the WG's energy has been completely focused on the dynamic flooding and these WG last calls didn't get the deserved attention. 
>
> As for as your comments, the first two were discussed for over a year and half. There were other advantages as well. For example, the link attribute encoding reduced (OSPFv2) or eliminated (OSPFv3) the need to correlate LSA attributes for a single link. We will note your objection in the shepherds report on the documents. We could even include a pointer to your quagga code that took a different approach if you wish to provide one. 
>
> With respect to your comments on BGP-LS, this is out of scope for LSR. While I haven't seen NLRI that hits the limit, I'm confident that the IDR WG will come up with a solution. 
>
> Thanks,
> Acee
>
> On 5/23/19, 5:57 AM, "Lsr on behalf of [e-mail]" <[e-mail] on behalf of [e-mail]> wrote:
>
>     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
>     
>     
>     
>       
>     
>     
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