Hi, Aditya: Aijun Wang China Telecom
> On Nov 21, 2021, at 12:56, Aditya Kaul <[email protected]> wrote: > > > IMHO BGP(overlay service) should ideally be responsible for dishing out your > cuisine at the particular restaurant, so if your dish isn’t available you > shouldn’t head there in the first place. [WAJ] The IGP just to assure the road to the node or the node itself is available. If these are not available, even the BGP can dish out the cuisine, it is not available to the driver. > > Meanwhile, if you have the ABR as the inline RR changing the BGP NH to itself > and hiding the egress PE, even in that case ingress PE doesn’t need to worry > about the egress PE as long as BGP service route is available with ABR as NH > and let ABR figure out the available egress PE. [WAJ] Normally, the RR does not sit inline the forwarding path among PEs, but ABR does. If the PEs span multiple areas, your design requires several pairs of RR, but indeed we need only one pair of them to accomplish the BGP sessions across different areas. > I guess your other assumption might relate to BGP service convergence being > slower than the IGP but then that's a different discussion. > > Hopefully I am not misconstruing the thread's intent. > > Regards, > Aditya >> On Nov 21, 2021, at 11:30 AM, Aijun Wang <[email protected]> wrote: >> >> Hi, Robert: >> If the ABR know the restaurant are closing now, it can certainly let the >> driver change to the backup restaurant immediately and avoid the driver >> waste the miles. Wouldn’t this mechanism give the driver better experiences? >> >> Anyway, the unreachable information is rare, controllable. The >> implementation/operator can open it only to the loop back address of the PE >> or Tunnel Ends. >> >> Aijun Wang >> China Telecom >> >>> On Nov 21, 2021, at 09:03, Robert Raszuk <[email protected]> wrote: >>> >>> >>> >>>> The ABR should do the summary work based on the liveness, right? >>> >>> Really ??? >>> >>> It seems we are as the WG in a form of a disconnect on that one .. rather >>> fundamental to what IGPs are or are supposed to be. >>> >>> One way to look at them is an analogy to road signs which first tell you >>> the direction to state/country, then city, then district/province, then >>> street. They do not blast you with pulses or stars that there is no one at >>> home or that restaurant is closed. >>> >>> On the other hand some folks here state that while road signs are great >>> (summary analogy) we do need to know by road signs if the restaurant is >>> open before we head there. Hmm just imagine how would that work in >>> practice. Just imagine blasting this all over US when no one except few >>> folks is even interested in this information. Leave alone that their >>> infrastructure just is not designed to keep up with it. >>> >>> Removing summary just because x % of restaurants are closed would be like >>> putting duct tape on traffic signs. Yes with the e-signs it is technically >>> possible but is this the right thing to do ? >>> >>> If the restaurant is open you either use google service overlay (think BGP) >>> to tell you that with some amount of probability or you call them directly >>> and check before you jump into the car to drive (think directed in data >>> plane probe). >>> >>> Last even if the restaurant is open there is no assurance they will take >>> your order when you arrive as they may experience power outage or run out >>> of rice for your favourite meal. So liveness of the PE does not really mean >>> that your service will be delivered. >>> >>> Kind regards, >>> R. >>> >> >> _______________________________________________ >> Lsr mailing list >> [email protected] >> https://www.ietf.org/mailman/listinfo/lsr > > _______________________________________________ > Lsr mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/lsr
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