Shipped half of the original design on purpose: generalizing BSD's alt:
same-TTL annotation across backends is impossible - mtr's JSON aggregates
cycles and discards per-cycle next-hop variance, icmp_win/icmplib send one
probe per TTL by construction, and the Linux system-traceroute parser
doesn't model multi-IP hops even though the text can contain them. A
finding that only ever fires on macOS/Linux-system-binary would be worse
than not having it.
New probes/ecmp.py::detect_ecmp() takes N independently-run TraceResults
for the same target and diffs which IP showed up at each TTL - pure and
backend-agnostic, since it never touches capability detection. Flags
path.ecmp (info, multiple next hops exist - normal on a load-balanced
network) and path.ecmp_asymmetric (warn, branches differ by >20ms - the
diagnostic case, since one degraded branch of a load-balanced pair causes
intermittent slowness a single traceroute would never catch).
--ecmp is opt-in and deliberately excluded from --full: it multiplies
traceroute traffic against the same targets by ecmp.runs (capped at 5)
across ecmp.max_targets (capped at 3), sequential and sharing one
semaphore, only after the main fan-out has finished.
Live-tested against 2 real targets x 3 runs each - ran cleanly, correctly
reported no divergence on this network.
Part of plans/zesty-zooming-wilkinson.md (gitignored).
