Hi Tony,
On 19/11/2021 17:02, Tony Li wrote:
Hi Peter,
[WAJ] The problem is arose from the summary action of IGP, why let
other protocols solve it?
There is no ‘problem’ with the IGP. You seem to want liveness from
the IGP. That’s not a property that it was meant to provide.
today IGPs provide reachability for the host route of remote PEs. Both
up and down events are propagated everywhere. If such host route
becomes unreachable, it is being used by BGP PIC to trigger the reroute.
When summarization is in place, to help IGP to scale, the remote PEs'
reachability is announced in a form of a summary and host routes are
suppressed. Providing down notification for the host prefix covered by
the summary is similar in nature to what happens without the
summarization. And if that down notification can be done in smart way,
we are still better off compared to what we do today without a
summarization.
And if it was done in a smart way, you could do so without ANY impact to
scalability. I outlined the mechanism for you already.
You can call it liveness or something else, but IGPs are already doing
so without the summarization. Arguing that it's not a property that
IGPs were meant to provide is misleading.
This is incorrect. Liveness is a side-effect in a flat area. It is NOT
something that the routing layer provides. Consider the case of a host
that is not participating in the IGP. You have reachability information
for it and path computation, as the IGP is designed to provide, but you
do not have liveness.
yes, but it's not specific to flat areas. Even in multi-area deployments
the host routing is mandated by MPLS. In these multi-area deployments
the host routes are sent everywhere, updates are triggered regardless of
the failure type. IGPs are effectively providing liveness service
between PEs in any MPLS network.
If you are not willing to have an architectural discussion, then there’s
not much of a point in having a working group.
don't take me wrong, I'm not trying to avoid the architectural
discussion, quite the opposite.
If IGPs can provide full liveness service between PEs today, why doing
'optimized negative liveness service' would be architecturally wrong?
thanks,
Peter
If you’re going to call every argument misleading, there’s also not much
point in a working group. Les asked me for a clear explanation. I’ve
done my best to provide that and apparently, I haven’t earned enough
respect for it to be seriously considered. Ok, so be it. I was not
looking for the Argument Clinic
(https://www.dailymotion.com/video/x2hwqn9). Let’s agree to disagree.
Tony
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