The civic NOC must confirm a leaf installs multipath next hops toward all spines for its fabric prefixes. What monitoring check best verifies underlay ECMP?
Select an answer to reveal the explanation.
Short Explanation
ECMP is only real when the leaf’s map shows several equal-cost doors to the spines—not when you pinged one door and hoped. Look at the installed multipath next hops for those fabric prefixes.
Full Explanation
The civic NOC verifies underlay ECMP by inspecting forwarding and routing state to confirm multiple equal-cost next hops are installed toward the spines for the leaf’s fabric prefixes—commonly remote leaf loopbacks. Multipath is proven only when those next hops exist in the RIB/FIB; hopeful assumptions from a single successful probe do not establish that every spine is actually in the ECMP set for production forwarding.
Pinging only the first spine management address and assuming all other spines participate in ECMP does not verify multipath installation for fabric prefixes. Clearing the ARP cache on one access VLAN does not refresh underlay multipath entries and confuses access/overlay adjacency with leaf-spine ECMP. Comparing NTP stratum values across spines is unrelated to whether equal-cost fabric next hops are programmed.
Exam caveat: show installed multipath next hops; management-plane ping is not an underlay ECMP proof.
Operational check: on a representative leaf, display the route to a remote leaf loopback and confirm next hops list all intended spines; shut one fabric uplink in a maintenance window and verify traffic shifts cleanly without blackholing VTEP reachability.