*>>> What if North/Central/South links are designed to protect each other under a single failure scenario ? And while perhaps saving some money by shutting Central and South, are we not making our SLAs thin when it comes to potential failure of North when C/S are off and there is no other protection path available (especially quite topology dependent in MPLS-TE networks) ? *
Sufficient guardrails are in place to ensure no compromise in resiliency. The expectation is that the intelligence that determines whether a TE link needs to be put to sleep is aware of any backup paths (in-use or not) that traverse this link and makes an informed decision based on that. If RSVP-TE is in use, there is sufficient state on the node itself to make an informed decision. Regards, -Pavan On Fri, May 22, 2026 at 2:42 AM Robert Raszuk <[email protected]> wrote: > Hi Tony, > > Ok so *all* headends need to be smart and apply rule of traffic > aggregation (180 degrees to one of traditional uses of TE which is traffic > spreading over available topology). Then again *all* headends need to be > super smart to say Oh those 100 headends from opposite side is aggregating > traffic over North ... I will try to do the same. To me the > correlation between traffic removed from South and Central to take North > link from A to B is missing such that B to A knows that increase of > reservations on North actually were caused by traffic shift from > South/Central. > > Yes this is mapping traffic to LSPs which to the best of my recollection > we do not flood. > > Of course as we all agree that all works with 100% RSVP-TE forwarding in > the network. > > > But let's put that aside for a moment - I have a different question which > popped up yesterday. > > All wise operators today build networks and use various FRR techniques to > minimize packet loss upon link or node failure. Waiting for any protocol > convergence IMHO is a thing of the past when it comes to connectivity > restoration time. > > I am not seeing where in this entire story we are taking this aspect into > consideration. What if North/Central/South links are designed to protect > each other under a single failure scenario ? And while perhaps saving some > money by shutting Central and South, are we not making our SLAs thin when > it comes to potential failure of North when C/S are off and there is no > other protection path available (especially quite topology dependent in > MPLS-TE networks) ? > > And while in theory headends do have all information to possibly make > what-if analysis for any network failure I strongly doubt that they will be > able to predict FRR options on possible potential shutdown of surrounding > links in the topology when making the traffic aggregation decisions. > > Regards, > Robert > > > > On Thu, May 21, 2026 at 12:06 PM Tony Li <[email protected]> wrote: > >> >> Hi Robert, >> >> > But I see no connection nor hint for also consolidating traffic from B >> to A to the North path. Traffic B to A may have completely different >> characteristics then traffic from A to B. And unless we are talking UDLR >> freeing links must be done bidirectionally - wouldn't you agree ? >> >> >> RFC 5305 tells us the unreserved bandwidth on the link. If you look at >> both ends of the link, you get both directions. That’s the hint. >> >> Tony >> >> _______________________________________________ > Lsr mailing list -- [email protected] > To unsubscribe send an email to [email protected] >
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