Robert,
On 22/11/2021 15:26, Robert Raszuk wrote:
Peter - the spec does not present full story. Hardly no RFC
presents full A--Z on how to run a network or even a given feature. It
provides mechanism which can still permit for building LDP LSPs
without host routes.
So anyone claiming it is impossible by architecture of MPLS is simply
incorrect.
As example - some vendors support ordered LDP mode some do not. Some
support BGP recursion some do not. And the story goes on.
But I am not sure what point are you insisting on arguing ... If it is
ok to run host routes across areas we have no problem to start with so
why to propose anything new there.
all I'm trying to say is that IGPs do advertise host routes across areas
today. Yes, it is sub-optimal, but hardly architecturally incorrect
IMHO. We want to improve and allow effective use of aggregation, while
keeping the fast notification about egress PE reachability loss in place
to help overlay protocols converge fast. The situation would be much
improved compared to what we have today.
thanks,
Peter
Moreover as you very well know tons of opaque stuff is attached today to
leaked host routes and this curve is going up. So when you summarise you
stop propagating all of this. Is this really ok ?
Do not get me wrong I love summarization but it seems as discussed off
line - we would be much better to leak host routes with opaque stuff
when needed rather then then leak blindly everything everywhere.
Cheers,
R.
On Mon, Nov 22, 2021 at 3:12 PM Peter Psenak <[email protected]
<mailto:[email protected]>> wrote:
On 22/11/2021 15:00, Robert Raszuk wrote:
>
> it's not a choice, that is an MPLS architectural requirement
and it
> happens in every single SP network that offers services on
top of MPLS.
> If that is considered architecturally incorrect, then the
whole MPLS
> would be. But regardless of that, it has been used very
successfully
> for
> last 30 years.
>
>
> No. Please read RFC5283.
and how many SPs have deployed it?
Hardly any, and maybe because of what is described in section-7.2
"For LER failure, given that the IGP
aggregates IP routes on ABRs and no longer advertises specific
prefixes, the control plane and more specifically the routing
convergence behavior of protocols (e.g., [MP-BGP]) or applications
(e.g., [L3-VPN]) may be changed in case of failure of the egress LER
node."
And what RFC5283 suggests in the same section is:
"Advertise LER reachability in the IGP for the purpose of the
control plane in a way that does not create IP FIB entries in the
forwarding plane."
Above defeats the prefix aggregation.
Peter
>
> Thx,
> R.
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