Robert,
On 03/01/2022 18:04, Robert Raszuk wrote:
Peter,
> We want network to be summarized all times
Please - can you answer my question which was already stated at least
twice ?
How can you summarize PE addresses if outside of reachability they
advertise and leak across areas lots of other important information in
an opaque to the IGP meaning ?
like what?
thanks,
Peter
What other transport those opaque gen-art /gen-app information will
take once you summarize the reachability and stop inter-area leaking ?
Many thx,
R.
On Mon, Jan 3, 2022 at 5:56 PM Peter Psenak <[email protected]
<mailto:[email protected]>> wrote:
Chris,
On 03/01/2022 17:18, Christian Hopps wrote:
>
> Peter Psenak <[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]>> 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]>
>>> https://www.ietf.org/mailman/listinfo/lsr
<https://www.ietf.org/mailman/listinfo/lsr>
>>>
>
>
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