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About the underlay/overlay taxonomy #20

Closed Deguello1 closed 10 months ago

Deguello1 commented 1 year ago

the "underlay infrastructure" indicates an IP/MPLS network that is not necessarily CATS-aware. The P-CS-computed CATS routes will be distributed among the overlay CATS-Routers, and will not affect the underlay nodes.

This reads like a pretty strong statement. It not only assumes that CATS routers are distinct from IP/MPLS routers of the underlay (which is highly debatable). It also asssumes that CATS routers will not affect (whatever that means) undermlay nodes: it seems to me that LIBs and FIBs maintaintes by PE routers (for example) may very well be populated by P-CS-computed routes (at least I fail to understand why not). So, I thiçnk this should deserve some elaboration. In addition, the IP/MPLSunderlay could contribute to the improvement of C-PS-computed routes (e.g., by means of Segment Routing). So, I don't think the underlay/overlay is that black and white.

dzpzp commented 1 year ago

IMO, the CATS routers can have the full ability of the IP/MPLS routers; meanwhile, the CATS routers support the additional ability about traffic steering defined in CATS. The current underlay technology can meet the forwarding requirement of the CATS traffic. Anyway, maybe some intent for example low-latency of the CATS traffic can be synchronized to the underlay.

VMatrix1900 commented 10 months ago

The underlay infracture is just a bunch of P nodes which are not supposed to be aware of CATS related metric.