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) <[email protected]>
*Sent:* Thursday, July 29, 2021 2:00 AM
*To:* Tony Li <[email protected]>
*Cc:* [email protected]; Shraddha Hegde <[email protected]>
*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 <[email protected] <mailto:[email protected]>> *On
Behalf Of *Tony Li
*Sent:* Wednesday, July 28, 2021 1:06 PM
*To:* Les Ginsberg (ginsberg) <[email protected]
<mailto:[email protected]>>
*Cc:* [email protected] <mailto:[email protected]>; Shraddha Hegde
<[email protected]
<mailto:[email protected]>>
*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
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