Re: [Lsr] A new version of I-D, draft-liu-lsr-isis-ifit-node-capability-02

Hi Joel,

> Robert, you seem to be asking that we pass full information about the
> dynamic network state to all routers

No not at all.

Only TE headends need this information.

To restate ... I am not asking to have a synchronized input to all routes
in the domain such that their computation would be consistent.

I am only asking for TE headends to be able to select end to end paths
based on the end to end inband telemetry data. I find this a useful
requirement missing from any of today's operational deployments.

Many thx,
R.

On Fri, Apr 3, 2020 at 12:59 AM Joel M. Halpern <jmh@joelhalpern.com> wrote:

> Robert, you seem to be asking that we pass full information about the
> dynamic network state to all routers so that they can, if needed, serve
> as fully intelligent path computation engines.  If you want to do that,
> you will need more than just the telemetry.  You will need the demands
> that are coming in to all of those routers, so that you can make global
> decisions sensibly.
> Which is why we use quasi-centralized path computation engines.
>
> Yours,
> Joel
>
> On 4/2/2020 6:16 PM, Robert Raszuk wrote:
> >
> >      > If you consider such constrains to provide reachability for
> >     applications you will likely see value that in-situ telemetry is
> >     your friend here. Really best friend as without him you can not do
> >     the proper end to end path exclusion for SPT computations..
> >
> >     [as wg member] Are you thinking that shifting traffic to a router is
> >     not going to affect it's jitter/drop rate?
> >
> >
> > Well this is actually the other way around.
> >
> > First you have your default topology. They you are asked to
> > construct new one based on applied constrains.
> >
> > So you create complete TE coverage and start running end to end data
> > plane probing over all TE paths (say SR-TE for specific example). Once
> > you start collecting the probe results you can start excluding paths
> > which do not meet your applied constraints. And that process continues.
> >
> > To your specific question - It is not that unusual where routers degrade
> > their performance with time and in many cases the traffic is not the
> > cause for it but internal bugs and malfunctions.
> >
> > Best,
> > R.
> >
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>