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

[Robert Raszuk <[e-mail]>]

Hi Greg,

That is 100% correct. That in fact goes well against the main principle of
end to end path based measurements in the data plane.

Collecting information by all nodes would inherently not include their own
forwarding characteristics so in my books is of very marginal use.

Thx,
R.


On Fri, Apr 3, 2020 at 1:08 AM Greg Mirsky <[e-mail]> wrote:

> Hi Robert,
> I think that there's no apparent requirement to collect performance
> information form each node in the network in order to select a path with
> bounded delay and packet loss. Would you agree?
>
> Regards,
> Greg
>
> On Thu, Apr 2, 2020 at 4:03 PM Robert Raszuk <[e-mail]> wrote:
>
>> 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 <[e-mail]>
>> 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.
>>> >
>>> > _______________________________________________
>>> > Lsr mailing list
>>> > [e-mail]
>>> > https://www.ietf.org/mailman/listinfo/lsr
>>> >
>>>
>> _______________________________________________
>> Lsr mailing list
>> [e-mail]
>> https://www.ietf.org/mailman/listinfo/lsr
>>
>