Hi, I share similar opinion with Gunter.
ASLA provides the flexibility to define the set of applications which can use a specific type of link attribute, it also allows to customize the attribute value for each application. As the generic metric mechanism will be used to define different types of new metrics, some of which may need the flexibility of indicating the set of applications it is used for, and may also need to generate application-specific metric values. In that case, it seems ASLA is the suitable approach for such metric advertisement. Best regards, Jie > -----Original Message----- > From: Lsr [mailto:lsr-boun...@ietf.org] On Behalf Of Van De Velde, Gunter > (Nokia - BE/Antwerp) > Sent: Friday, July 30, 2021 5:06 PM > To: Peter Psenak <ppsenak=40cisco....@dmarc.ietf.org>; Shraddha Hegde > <shraddha=40juniper....@dmarc.ietf.org>; Les Ginsberg (ginsberg) > <ginsberg=40cisco....@dmarc.ietf.org>; Tony Li <tony...@tony.li> > Cc: lsr@ietf.org > Subject: Re: [Lsr] Generic metric: application-specific vs > application-independent > > A little late in the discussion... (PTO events do happen) > > a quick opinion on the below discussion on whether Generic metric sub-tlv > should be encoded on a ASLA or not. > For me, it depends on how the metric for the corresponding metric-type is > obtained and if it can be configured (static). > It doesn’t make sense to have Application specific values if a particular > metric > is obtained only dynamically, for eg, dynamically measured delay is going to > be same for all applications. > On the contrary, te-metric can be configured, and we can in principle > configure > different values for different applications. > > My opinion is that if any of the metric-types in the Generic metric sub-tlv > can > be configured, it should be inside the ASLA. > > G/ > > -----Original Message----- > From: Lsr <lsr-boun...@ietf.org> On Behalf Of Peter Psenak > Sent: Friday, July 30, 2021 9:42 AM > To: Shraddha Hegde <shraddha=40juniper....@dmarc.ietf.org>; Les Ginsberg > (ginsberg) <ginsberg=40cisco....@dmarc.ietf.org>; Tony Li <tony...@tony.li> > Cc: lsr@ietf.org > Subject: Re: [Lsr] Generic metric: application-specific vs > application-independent > > Shraddha, > > On 30/07/2021 06:53, Shraddha Hegde wrote: > > Operators have built their networks with link attributes > > > > being configured and used by any application. For example > > > > igp-metric is used by ISIS, then came LDP that used same igp-metric, > > > > RSVP could also use igp-metric. Then came ISIS-SR and SR-TE > > > > and even flex-algo. All these applications could use the same igp-metric. > > > > The networks have evolved like this for 20-30 years. > > > > If an operator wants to design his network for this kind of > > > > network evolution with generic metric going forward, ASLA does not > > > > currently provide an effective solution. > > please be more specific as to what exactly "ASLA does not currently provide an > effective solution" for. > > > ASLA currently has limitations > > > > that make it more complex than necessary for operators who want to > > > > evolve their networks this way. > > above seems more like your opinion than the fact. I have not seen any > evidence that would prove the above statement. > > > > > > I am working on a draft to propose improvements to ASLA to > > > > make this kind of evolution less complex. I'll post a draft > > > > soon that will describe limitations of ASLA in its current form > > > > along with proposed improvements. > > > hard to comment on something that does not exist. > > > > > > I would still like to hear about use cases that require > > > > generic metric to be applications-specific and cannot be solved with > > > > application-independent generic metric. > > it has been explained on the list multiple times. > > > thanks, > Peter > > > > > > Rgds > > > > Shraddha > > > > Juniper Business Use Only > > > > *From:* Les Ginsberg (ginsberg) <ginsberg=40cisco....@dmarc.ietf.org> > > *Sent:* Thursday, July 29, 2021 2:00 AM > > *To:* Tony Li <tony...@tony.li> > > *Cc:* lsr@ietf.org; Shraddha Hegde <shrad...@juniper.net> > > *Subject:* RE: [Lsr] Generic metric: application-specific vs > > application-independent > > > > *[External Email. Be cautious of content]* > > > > Tony – > > > > You ask very important questions – but – as Acee has answered in a > > subsequent email – all of these questions were openly debated in the > > WG during the work on what became RFC8919/8920. This debate was > > contentious, took years, and the WG eventually reached consensus on > > what became the two RFCs. > > > > If every time a new attribute is defined we reopen the original > > debate, then we will never move forward and we will have great > > difficulty in deploying interoperable implementations. > > > > I can respect that you might have preferred a different conclusion on > > the part of the WG – but I hope you will also acknowledge that this is > > now a resolved issue and we need to move forward following the > > existing RFCs. > > > > Parenthetically, I do believe that answers to your questions can be > > found in the RFCs. The answers may not satisfy you – but we did > > attempt to include the context which drove the ASLA solution. > > > > Thanx. > > > > Les > > > > *From:* Lsr <lsr-boun...@ietf.org <mailto:lsr-boun...@ietf.org>> *On > > Behalf Of *Tony Li > > *Sent:* Wednesday, July 28, 2021 1:06 PM > > *To:* Les Ginsberg (ginsberg) <ginsb...@cisco.com > > <mailto:ginsb...@cisco.com>> > > *Cc:* lsr@ietf.org <mailto:lsr@ietf.org>; Shraddha Hegde > > <shraddha=40juniper....@dmarc.ietf.org > > <mailto:shraddha=40juniper....@dmarc.ietf.org>> > > *Subject:* Re: [Lsr] Generic metric: application-specific vs > > application-independent > > > > Les, > > > > ASLA exists to support the advertisement of attributes which can be > > used in application specific ways. > > > > Why do we need separate and different copies of attributes for > > different applications? > > > > The SRLG tries to capture the risk relationships between multiple links. > > Those relationships don’t change depending on the application. > > > > Link attributes don’t require the variability that ASLA provides, and > > the overhead is high. How does this cost/benefit ratio make sense? > > > > In any particular deployment case, a given attribute advertisement > > might be used by one app, multiple apps, or all apps. > > > > ASLA allows to unambiguously support all of these cases with a > > single advertisement encoding format. > > > > The correct question to be resolving here is indeed the question > > which has been discussed in an earlier thread: Is Generic Metric a > > link attribute which can have application specific use cases? I > > think the question to that is unquestionably “yes”. > > > > That should be enough (IMO of course) to close the discussion. > > > > Well, one nice thing is that there is an entire space of metrics > > available. If application A wants to use metric 16 and application B > > wants to use metric 122, that’s already doable. > > > > Why do we need a separate space per application???? > > > > Tony > > > > _______________________________________________ > Lsr mailing list > Lsr@ietf.org > https://www.ietf.org/mailman/listinfo/lsr > _______________________________________________ > Lsr mailing list > Lsr@ietf.org > https://www.ietf.org/mailman/listinfo/lsr _______________________________________________ Lsr mailing list Lsr@ietf.org https://www.ietf.org/mailman/listinfo/lsr
