Hi Robert,
On 27/03/2023 10:05, Robert Raszuk wrote:
Hi,
I would like to get more clarification in respect to extending External
LSAs for UPA. Area summary use case is pretty clear - but in case of
redistribution (typical src of external LSAs) IMO we are going way too
far with this. Let's all keep in mind that this is a pulse designed to
trigger upper protocol switchover.
Needless to say that would work only via one hop by design as
redistribution happens via RIB and by definition of UPA unreachable
routes are not being installed in RIB in the first place.
there are two cases we need to distinguish:
1. ASBR is redistributing routes and creating a summary out of that. In
such case the ASBR may create the UPA for a summarized prefix for which
it lost reachability in the source domain.
2. UPA as such is crossing multiple domains with redistribution.
The fact that UPA is not installed in forwarding does not mean it can
not be redistributed. How that is done is an implementation detail. The
whole redistribution is implementation specific.
I let others co-authors to respond to the below, as I'm not entirely
convinced we need the UP-flag.
thanks,
Peter
On the apparently relative terms I do not see a need for the UP Flag.
First planned maintenance should be solved by BGP protocol and there are
already a number of tools in BGP allowing one to do it.
Second, if you say this is needed for BGP free deployments then I
question the merit on the basis that UPA is ephemeral and expires say in
120 sec which will not be enough for most planned maintenance work. So
if someone insists to add UP Flag it should be not just a bit but also a
time or time delta from set UTC where it is expected that provided
prefix will be down,
Kind regards,
R.
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