Hello!
Thanks for an excellent lesson.
I have a doubt: on the lesson, Rene configures maximum-paths on the underlay BGP to be able to “ECMP” traffic… From my understanding, and please correct me if wrong, is possible to ECMP multicast traffic (ARP Requests flooded, …) thanks to be able to reach the Anycast address of the RP via all SPINE switches, so that different LEAF switches send their PIM Joins to different SPINE switches. Is this correct?
However, from a single VNI perspective, how is VXLAN encapsulated traffic going to be ECMPd? The source and destination IP are always the same (VXLAN tunnel source and destination). So is ECMP considered among traffic from multiple VNIs then? (different VXLAN IP destinations).
What about fragmentation? I have talked to a lot of network engineers that are afraid and negative about ECMP because they say that, if fragmentation happens, things can go bad with the packet reordering… is that why Rene recommends to increase the MTU in one of its lessons?
Thanks,
Jose