Hi Greg,
On 04/01/2022 18:13, Greg Mirsky wrote:
Hi Peter,
I'm probably missing something in the current PULSE but I cannot find
the mechanism that limits the number of the pulses. Do you envision that
being like a throttling mechanism? But delaying the propagation of
notification for some events might cause more instability in a network.
no. It's a limit not a delay. If too many edge nodes loose connectivity
to the ABR in its area, it's a result of the severe event like area
partition or loss of area connectivity from ABR. These are not types of
events that we are trying to address with pulses.
The limit is not described in the published version of the draft.
We are working on the updated version that will include the description
of it.
thanks,
Peter
Regards,
Greg
On Tue, Jan 4, 2022 at 1:52 AM Peter Psenak <[email protected]
<mailto:[email protected]>> wrote:
Hi Greg,
On 03/01/2022 23:17, Greg Mirsky wrote:
> Happy New Year to All!
>
> Hi Peter,
> Top-pasting:
> In 99,99% of cases there will be only single pulse generated when
one PE
> goes down. That itself is a very rare event itself.
>
> We can easily limit the number of pulses generated on ABR to a single
> digit number to cover the unlikely case of many PEs in area becoming
> unreachable at the same time.
>
> I think that it is possible for the summarizing ABR to get
disconnected
> from the IGP area in such a way that the summarization is still
valid.
> If such a case is valid, would the ABR generate PULSE for each
> disconnected PE?
obviously not. That's why I mentioned the number of pulses will be
limited on every ABR.
thanks,
Peter
>
> Regards,
> Greg
>
> On Mon, Jan 3, 2022 at 8:56 AM Peter Psenak
> <[email protected]
<mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>>>
> wrote:
>
> Chris,
>
> On 03/01/2022 17:18, Christian Hopps wrote:
> >
> > Peter Psenak <[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>> writes:
> >
> >> On 03/01/2022 16:21, Christian Hopps wrote:
> >>>
> >>>> On Nov 29, 2021, at 7:39 PM, Les Ginsberg (ginsberg)
> <[email protected]
<mailto:[email protected]>
> <mailto:[email protected]
<mailto:[email protected]>>> wrote:
> >>>>
> >>>> Tony –
> >>>> Let me try one example – see if it helps.
> >>>> Summarization is used in the network.
> >>>> But customer identifies a modest number of key nodes
where it
> wants to detect loss of reachability ASAP. Unfortunately,
customer
> is unable to assign addresses which are outside of the summary to
> these nodes.
> >>>
> >>> I think this does in fact capture the problem trying to be
> solved here, nicely.
> >>
> >> not really.
> >> In fact assigning addresses to the nodes in a way that
they are
> part of the
> >> summary is the right thing to do.
> >
> > No, not if you want more detailed information about specific
> reachability it's not. And ....
>
>
> typically you want to summarize all prefixes inside the area when
> advertising outside the area. And you want to know about some
of these
> prefixes when they are lost to help convergence.
>
>
> >
> >> The problem we are trying to solve is to use the
summarization
> but without the
> >> loss of the fast notification of the node down event.
> >
> > You want more specific information about reachability, but you
> just want to do it when the network is stressed and
undergoing change.
> >
> > So the "works now" way of not summarizing these important
> prefixes has the state in the network when it's working, so
you know
> adding and removing it is something the network is already
capable
> of handling.
> >
> > New signaling that *only* is created when things start
failing,
> tests the infrastructure at exactly the wrong time.
>
> In 99,99% of cases there will be only single pulse generated when
> one PE
> goes down. That itself is a very rare event itself.
>
> We can easily limit the number of pulses generated on ABR to
a single
> digit number to cover the unlikely case of many PEs in area
becoming
> unreachable at the same time.
>
>
> >
> > If a failing network can handle the extra state, then a
> functioning stable network of course can too.
>
> no, that's not what we claim. We want network to be
summarized all
> times
> and generate limited number of pulses at any given time to
help the
> network converge fast in case where single (or very few) PEs
in an area
> go down.
>
> thanks,
> Peter
>
>
>
> >
> > Thanks,
> > Chris.
> >
> >>
> >> thanks,
> >> Peter
> >>
> >>
> >>> One solution very simple solution that works today is:
> >>> - Tell the customer they can't do this, but they *can*
modify
> their addressing
> >>> (this is literally what they do for a living) so that they
> don't have this
> >>> problem.
> >>> Do we *really* want modify our IGPs (a BIG ask) with some
> pretty questionable
> >>> changes, just to save the operators the trouble of doing
their
> job correctly?
> >>> Maybe the answer here is this isn't a good idea, and we
should
> move on...
> >>> Thanks,
> >>> Chris.
> >>> [as wg member]
> >>> _______________________________________________
> >>> Lsr mailing list
> >>> [email protected] <mailto:[email protected]> <mailto:[email protected]
<mailto:[email protected]>>
> >>> https://www.ietf.org/mailman/listinfo/lsr
<https://www.ietf.org/mailman/listinfo/lsr>
> <https://www.ietf.org/mailman/listinfo/lsr
<https://www.ietf.org/mailman/listinfo/lsr>>
> >>>
> >
> >
>
> _______________________________________________
> Lsr mailing list
> [email protected] <mailto:[email protected]> <mailto:[email protected]
<mailto:[email protected]>>
> https://www.ietf.org/mailman/listinfo/lsr
<https://www.ietf.org/mailman/listinfo/lsr>
> <https://www.ietf.org/mailman/listinfo/lsr
<https://www.ietf.org/mailman/listinfo/lsr>>
>
_______________________________________________
Lsr mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/lsr
