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AntHocNet 2.0.0
Paper-faithful ant-colony ad hoc routing: the shared core and its adapters
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#include <anthocnet/core/config.h>
Public Attributes | |
| double | alpha = 0.7 |
| Pheromone reinforcement / evaporation weights. | |
| double | hopCountAlpha = 0.0 |
| The thesis's α — hop-count moving average, eq. | |
| double | gamma = 0.7 |
| GAMA: weight of the old value when reinforcing. | |
| double | betaAnts = 20.0 |
| Eq.1 exponents for the stochastic next-hop choice, from the primary source (#179): Ducatelle, Adaptive Routing in Ad Hoc Wireless Multi-hop Networks, PhD thesis, USI Lugano, 2007 — beta1 (reactive ants, eq 4.1) "we keep beta1 relatively high, on 20"; beta2 (proactive ants, eq 4.5) "normally kept on 20"; beta3 (data, eq 4.6) "we normally keep beta3
on 20". | |
| double | betaData = 20.0 |
| exponent for data next-hop choice (thesis beta3). | |
| double | hopTimeSec = 0.003 |
| Per-hop time estimate used by the back-ant pheromone formula (Eq.2): the time to take one hop in unloaded conditions. | |
| bool | enableMacMetric = false |
| Congestion-aware per-hop cost (item 10/A2, [1] §3.2): when on and an ILinkState is injected, a forward ant records each node's expected send time (Q_mac+1)*T̂_mac instead of its own wall-clock transit delta, so the path-time term T̂_d reflects sustained MAC load. | |
| double | minPheromone = 0.00001 |
| Links whose pheromone drops below this are pruned. | |
| bool | enableEvaporation = true |
| Time-proportional evaporation (ADR-0012): a secondary safety net, the only source of aging (reinforcement no longer ages competitors). | |
| double | evaporationInterval = 1.0 |
| reference interval (s) for the decay. | |
| double | reactiveRetryInterval = 1.0 |
| At most one reactive forward ant per destination per this window, so a stream of packets to an unreachable destination doesn't flood ants ([1] §4.2). | |
| bool | enableProactive = true |
| Proactive / diffusion subsystem (ADR-0007), config-gated so the benchmark ablation (item 08) can justify the shipped default. | |
| bool | enableDiffusion = true |
| hello pheromone adverts + virtual table. | |
| std::size_t | maxHelloAdverts = 10 |
| Diffusion advert cap k: at most this many destinations per hello ant (#186). | |
| bool | enableReactive = true |
Per-ant-type gates, completing the ablation surface the other enable* flags already provide. | |
| bool | enableRepair = true |
| local repair ants after a link break ([1] §3.5). | |
| bool | enableLinkFail = true |
| link-failure notifications ([1] §3.5). | |
| bool | enableDirectedReactive = false |
| Directed reactive discovery (default off — an explicit deviation from [1] §3.1, kept behind a gate until a benchmark justifies it). | |
| double | proactiveBroadcastProb = 0.1 |
| Per-hop probability that an in-transit proactive forward ant is broadcast to explore for new paths rather than unicast along pheromone ([1] §3.3). | |
| double | sessionTtl = 5.0 |
| A destination stays an "active session" (and is probed by proactive ants) for this many seconds after the last locally-originated data packet to it. | |
| double | proactiveVirtualMargin = 0.0 |
| Emission gate for proactive forward ants (issue #180). | |
| double | helloInterval = 1.0 |
| Timer intervals (seconds). | |
| double | proactiveInterval = 10.0 |
| Proactive forward-ant period per active session. | |
| double | lifeAnt = 2.0 |
| int | allowedHelloLoss = 2 |
| A neighbour is presumed gone after this many missed hellos (maxIdle = helloInterval * allowedHelloLoss), per [1] §3.5. | |
| int | repairMaxBroadcasts = 2 |
| Max times a repair / link-failure ant may be (re)broadcast before being dropped, so local repair and failure notifications can't storm ([1] §3.5). | |
| double | linkfailNotifyInterval = 5.0 |
| Minimum spacing (s) between LinkFail notifications this node originates about the same destination. | |
| int | txFailureThreshold = 3 |
| Consecutive MAC transmit-failures to the same next hop (with no reception from it in between) before the adapter's fast-path detector (ADR-0008 detector D) treats the link as broken. | |
| int | reactiveMaxBroadcasts = -1 |
Max times one node may broadcast one reactive generation (src, seqNum). | |
| bool | enableMultipath = true |
| Multipath reactive setup ([1] §3.1, issue #96): when on, a later reactive forward ant of an already-seen generation is forwarded if it passes the antAcceptanceFactor band below, laying down multiple good paths — and losing a best hop that leaves a usable alternate is absorbed instead of flooding a LinkFail (the churn bound; without it multipath regressed PDR on the ns-3 disk-model harness, #96 round 1). | |
| double | antAcceptanceFactor = 0.9 |
| Multipath acceptance factor ([1] §3.1, "empirically set to 1.5"), used only when enableMultipath is on: a later same-generation reactive forward ant is forwarded only if both its hop count and its travel time are within this factor of the best ant of that generation seen so far. | |
| double | antAcceptanceFactorNewHop = 2.0 |
Disjoint-path acceptance factor a2 — the less restrictive factor applied when a reactive forward ant's first hop (the node it travelled to immediately after the source) has not been seen among the ants this node already accepted for that (src, seqNum) generation: | |
| int | proactiveMaxBroadcasts = 2 |
| Max times a proactive forward ant may be (re)broadcast — covering both the per-hop exploratory broadcast ([1] §3.3) and a route gap en route. | |
| double | repairWaitFactor = 5.0 |
| Local repair wait ([1] §3.5): after launching a repair ant, wait repairWaitFactor × the estimated end-to-end delay of the lost path for a backward repair ant; if none arrives, discard the buffered packets for that destination and send a link-failure notification (spec D6). | |
| double | repairTimeout = 1.0 |
| Flat repair wait (seconds) used when the lost path has no usable delay estimate (e.g. | |
| int | networkDiameter = 30 |
| Conservative upper bound on path length for the expanding-ring search. | |
| std::size_t | maxPathLength = 100 |
| Bound the visited-node stack carried in a packet, and the (src,seq) dedup history, so a long-running simulation cannot grow them without limit (a latent issue in the original fixed-size malloc arrays). | |
| std::size_t | maxHistory = 4096 |
| double anthocnet::core::Config::alpha = 0.7 |
Pheromone reinforcement / evaporation weights.
ALFA: evaporation retains alpha of the value per evaporationInterval (ADR-0012, a repo extension). This is NOT the thesis's α. The 2007 thesis has three distinct 0.7s: γ (pheromone running average → gamma), η (MAC send-time average → ns-3 MacServiceAlpha) and α (the hop-count moving average, eq. 4.2 → hopCountAlpha below). This field is none of them — the thesis has no evaporation term at all (#182, #185).
| double anthocnet::core::Config::hopCountAlpha = 0.0 |
The thesis's α — hop-count moving average, eq.
4.2: h ← α·h + (1−α)·h_ant, per (destination, next hop), applied before the hop count enters the pheromone metric (#185). 2007 thesis: "α is a parameter regulating how quickly the formula adapts to new information. In our experiments, α is always kept on 0.7." Defaults to 0.0, which makes h equal the ant's own hop count — exactly the pre-#185 behaviour — so enabling the thesis value (0.7) is an A/B decision, not a silent change. Must be in [0, 1).
| double anthocnet::core::Config::gamma = 0.7 |
| double anthocnet::core::Config::betaAnts = 20.0 |
Eq.1 exponents for the stochastic next-hop choice, from the primary source (#179): Ducatelle, Adaptive Routing in Ad Hoc Wireless Multi-hop Networks, PhD thesis, USI Lugano, 2007 — beta1 (reactive ants, eq 4.1) "we keep beta1 relatively high, on 20"; beta2 (proactive ants, eq 4.5) "normally kept on 20"; beta3 (data, eq 4.6) "we normally keep beta3 on 20".
All three are 20, so ants and data share one value here.
This is a deliberate departure from [1] (PPSN 2004), which gives no absolute values but does state a ratio: data uses pheromone squared (§3.2 "the square ... to be more greedy") while ants use it unsquared (§3.3 "not squared, so that they sample the paths more evenly"). At the thesis values that asymmetry disappears. The thesis reaches exploration by other means — proactive ants route on max(regular, virtual) pheromone and carry a per-node broadcast probability — rather than by a lower exponent. Same precedent as hopTimeSec (#88): the thesis supplies numbers the paper omits, and its numbers win where the two disagree.
Measured, not merely sourced (#179): a 20-seed x 900 s A/B over the six discrete scenarios, paired per seed, moved 5 of 6 to PAIRED-IMPROVED with no scenario regressing — PDR +0.50..+3.23 pp and routing load -9.7..-16.7% where significant. Only dense-small is neutral. The full table, the controls and the one adverse signal are on #179.
betaAnts conflates the thesis's beta1 (reactive) and beta2 (proactive), which the thesis parameterises separately. They coincide at 20, so the conflation is harmless here; it stops being harmless if we ever want a value the thesis does not have — the thesis itself sweeps beta2 alone in chapter 5. Split the field before deviating per ant type, not after. exponent for ant next-hop choice (thesis beta1/beta2).
| double anthocnet::core::Config::betaData = 20.0 |
| double anthocnet::core::Config::hopTimeSec = 0.003 |
Per-hop time estimate used by the back-ant pheromone formula (Eq.2): the time to take one hop in unloaded conditions.
In seconds, matching IClock, so it is comparable in magnitude to the measured path time. Value from the primary source (#88): Ducatelle, Adaptive Routing in Ad Hoc Wireless Multi-hop Networks, PhD thesis, USI Lugano, 2007 — "we kept thop on 0.003 sec". [1] (PPSN 2004) defines the constant but gives no number, which is why this was a provisional 50 ms until 2026-07-25. T_hop = 3 ms (2007 thesis)
| bool anthocnet::core::Config::enableMacMetric = false |
Congestion-aware per-hop cost (item 10/A2, [1] §3.2): when on and an ILinkState is injected, a forward ant records each node's expected send time (Q_mac+1)*T̂_mac instead of its own wall-clock transit delta, so the path-time term T̂_d reflects sustained MAC load.
Gated + default off so the simpler item-02 metric stays the shipped default until a benchmark justifies the switch.
| double anthocnet::core::Config::minPheromone = 0.00001 |
| bool anthocnet::core::Config::enableEvaporation = true |
Time-proportional evaporation (ADR-0012): a secondary safety net, the only source of aging (reinforcement no longer ages competitors).
Each tick ages every regular link by alpha^(dt/evaporationInterval). Gated so item 08 can run the paper-faithful "running-average only" ablation.
| double anthocnet::core::Config::evaporationInterval = 1.0 |
| double anthocnet::core::Config::reactiveRetryInterval = 1.0 |
| bool anthocnet::core::Config::enableProactive = true |
| bool anthocnet::core::Config::enableDiffusion = true |
| std::size_t anthocnet::core::Config::maxHelloAdverts = 10 |
Diffusion advert cap k: at most this many destinations per hello ant (#186).
2007 thesis: "picks a maximum number k of destinations it has routing information for. k is normally kept on 10" — and its §5.3.4 sweeps k = 0/2/5/10/20, reporting performance improving monotonically with k. Clamped to the wire bound kMaxHelloOnWire (64) so a large value can never produce a hello the codec would reject. Which k destinations fill the slots is a separate, documented deviation: active sessions first, then best pheromone (#26 item 6.5), where the thesis picks k at random — see docs/fidelity.md.
| bool anthocnet::core::Config::enableReactive = true |
Per-ant-type gates, completing the ablation surface the other enable* flags already provide.
All default true: turning none of them off reproduces current behaviour exactly. They exist so the question "which ant types earn their keep in regime X?" is a measurement rather than an argument — the same discipline that chose the multipath and A2 defaults.
There is deliberately no hello gate: ADR-0008 makes the hello-timeout detector the one mandatory liveness path, and hello also carries the diffusion adverts (enableDiffusion) and, on multi-interface adapters, the canonical→link-local peer mapping. Use helloInterval to make it cheaper; do not remove it.
Note enableReactive = false removes the only source of regular pheromone in the default configuration, so routes never form unless something else installs them — which is exactly the interaction enableDirectedReactive + enableDiffusion is there to test. reactive forward ants (route discovery).
| bool anthocnet::core::Config::enableRepair = true |
| bool anthocnet::core::Config::enableLinkFail = true |
| bool anthocnet::core::Config::enableDirectedReactive = false |
Directed reactive discovery (default off — an explicit deviation from [1] §3.1, kept behind a gate until a benchmark justifies it).
[1] broadcasts a reactive forward ant wherever the current node has no pheromone for the destination. That is the right move when nothing is known — but it ignores information the protocol has already collected: the virtual pheromone table, built from hello diffusion adverts (ADR-0007), frequently holds a usable gradient toward a destination for which no regular pheromone exists yet. selectNextHop only blends the virtual table in for proactive ants, so a reactive ant floods past it.
With this on, a reactive forward ant consults the virtual table before falling back to broadcast, and unicasts along it when it finds one. The flood becomes a directed walk wherever diffusion has reached, and stays a flood everywhere else.
Deliberately not position- or topology-specific: the gradient is the protocol's own, so this behaves identically on a MANET and on a satellite ISL mesh, and needs neither GPS (cf. LAR/GPSR) nor an orbital model. Nothing new travels on the wire — the virtual table is local state — so this costs no kWireVersion bump.
Risk to measure, not assume: a stale or wrong gradient sends the ant down a dead end where a flood would have found a path, trading overhead for discovery latency and possibly for delivery.
| double anthocnet::core::Config::proactiveBroadcastProb = 0.1 |
| double anthocnet::core::Config::sessionTtl = 5.0 |
| double anthocnet::core::Config::proactiveVirtualMargin = 0.0 |
Emission gate for proactive forward ants (issue #180).
The proactive timer considers one ant per active session; this is the fraction by which the best virtual pheromone for that destination must exceed the best regular pheromone before the ant is actually sent.
Ducatelle 2007 thesis (lines 4084-4088): *"In order to improve efficiency, the actual sending of a proactive forward ant is conditional to the availability of good new virtual pheromone: only if the best virtual pheromone is significantly better (in our experiments: at least 10% better) than the best regular pheromone, a proactive forward ant is sent out."*
Expressed as a margin (0.10 = "at least 10% better"), not as a 1.10 ratio, so that 0 reads unambiguously as "no margin required" — i.e. the gate is off and every considered ant is sent, reproducing pre-#180 behaviour for the ablation. See shouldSendProactive() for the boundary cases (no virtual pheromone; no regular route at all).
The comparison is per-link, not the thesis's literal best-vs-best (ADR-0018, the #180 re-derivation): pass iff some neighbour's virtual pheromone beats the regular pheromone on that SAME link by the margin, with a hint on an unsampled link passing trivially. The scalar best-vs-best form compares estimators of different paths; its ratio has a structural ceiling tau(h-1)/tau(h) ~ h/(h-1) (measured byte-exact by exp_uniformity_probe), so any fixed margin m silently disables the gate for destinations farther than 1 + 1/m hops — on the old, corrupted clocks this was measured as pass rates of 0-3.8 % and, when forced on, +36-68 % NRL / -5 to -6.4 pp PDR (PR #188). The per-link ratio is degree- and hop-independent (probe: centred 0.97-1.06).
Defaults to 0 (gate OFF). The re-derived shape makes a non-zero margin meaningful (probe-measured: m in 0.2-0.5 selects the genuine anomaly tail rather than a phase/hop artefact); adopting one as default is a benchmark decision on the regime that keeps proactive on (#248: satellite), owned by #180's A/B record. core/tests/exp_gate_cascade.cpp reproduces the historical failure.
| double anthocnet::core::Config::helloInterval = 1.0 |
| double anthocnet::core::Config::proactiveInterval = 10.0 |
Proactive forward-ant period per active session.
10.0 is the long-standing repo value with no recorded source (#182); the thesis's §5.3.3 measured optimum is 2 s, but adopting it is #248's sweep to decide — PR #252 accidentally shipped 2.0 here while claiming not to, which the per-merge refresh measured as NRL ×4.7 / PDR −12 pp at paper-base (#254). Do not change this default without that A/B.
| int anthocnet::core::Config::allowedHelloLoss = 2 |
| int anthocnet::core::Config::repairMaxBroadcasts = 2 |
| double anthocnet::core::Config::linkfailNotifyInterval = 5.0 |
Minimum spacing (s) between LinkFail notifications this node originates about the same destination.
Under link flapping (evict -> hello re-learn -> evict) every cycle re-broadcast a fresh note about the same destinations, making origins ~98% of linkfail volume (issue #20). The #20 sweep picked 5.0: 1 s misses the ~3+ s flap cycle (no effect), 10 s starts costing PDR/delay. 0 disables the cooldown (the original spec has no rate limit).
| int anthocnet::core::Config::txFailureThreshold = 3 |
Consecutive MAC transmit-failures to the same next hop (with no reception from it in between) before the adapter's fast-path detector (ADR-0008 detector D) treats the link as broken.
Debounces transient congestion drops: a single retry-limit drop in a dense/contended network is usually a collision, not a topology change, and evicting the neighbour on it destroys valid routes and triggers rediscovery floods (issue #19).
| int anthocnet::core::Config::reactiveMaxBroadcasts = -1 |
Max times one node may broadcast one reactive generation (src, seqNum).
-1 = unbounded. Default 2.
The unit of this field changed in #173 — read this before comparing it to an older run or an older sweep. It used to be a budget carried on the ant and decremented at every hop, i.e. per ant path; it is now a counter held at each node per generation. Same name, same default, different meaning — the alpha/ADR-0012 trap, so it is spelled out here (see docs/configuration.md).
Why per node. A reactive forward ant broadcasts wherever there is no pheromone for the destination, so a per-path budget is a hop limit on discovery: at 2, destinations more than ~5 hops away were permanently undiscoverable (#169), which is what made sparse/static fields look like an AntHocNet weakness. A per-node count does not limit reach at all — the ant may still travel arbitrarily far, each node along the way simply does not re-broadcast the same generation indefinitely.
Why a bound is needed at all, given the sources describe none. The 2007 thesis bounds proliferation by duplicate suppression ("subsequent copies
are destroyed"), maxPathLength and the antAcceptanceFactor band. But with enableMultipath on (the default) a reactive forward ant is admitted by the acceptance band instead of (src,seq) duplicate suppression, and the band admits rather than suppresses. Removing the per-path budget in #169 therefore left no bound: one discovery on a 7x7 grid cost 30,090 ants, and ns-3 large-scale fell to 21.7% PDR at NRL 3071 (#173). This restores duplicate suppression's intent for the one ant type that bypasses it.
Default is now -1 (unbounded), as of #177. The two-factor band below (a1=0.9 / a2=2.0) bounds the flood on its own — one discovery on a 7x7 grid costs 154 ants with no count in force, ~3.1n and flat in n — so the per-node counter is no longer load-bearing, and leaving it on cost delivery in dense graphs (heavy-load +1.8 pp, large-scale +4.7 pp at 11.6%/25.6% less overhead once removed). Kept configurable for sensitivity experiments; any finite value still bounds re-broadcasts per (node, generation).
| bool anthocnet::core::Config::enableMultipath = true |
Multipath reactive setup ([1] §3.1, issue #96): when on, a later reactive forward ant of an already-seen generation is forwarded if it passes the antAcceptanceFactor band below, laying down multiple good paths — and losing a best hop that leaves a usable alternate is absorbed instead of flooding a LinkFail (the churn bound; without it multipath regressed PDR on the ns-3 disk-model harness, #96 round 1).
When off, every ant type uses strict (src,seq) dedup — only the first-arriving copy propagates (single-path setup). Default on: with the churn bound, multipath beat single-path on every headline metric in the paper regime (PDR 92.3 vs 89.4, delay/jitter/NRL all no worse; #96 round 2).
| double anthocnet::core::Config::antAcceptanceFactor = 0.9 |
Multipath acceptance factor ([1] §3.1, "empirically set to 1.5"), used only when enableMultipath is on: a later same-generation reactive forward ant is forwarded only if both its hop count and its travel time are within this factor of the best ant of that generation seen so far.
Higher admits more copies (more multipath, up to a flood); 1.0 still admits equal-metric copies, so no factor value reproduces strict single-path dedup — that is what enableMultipath=false is for.
Default is 0.9, not the 1.5 of [1] §3.1, as of #177. The 2007 Ducatelle thesis describes the same mechanism but states the value its authors actually ran, and it is below 1.0:
"If the number of hops and travel time of a newly received ant are both within an acceptance factor a1 of those of the best previously received ant of the same route setup, the new ant is accepted and forwarded; otherwise, it is discarded. a1 is set quite low (to 0.9), in order to only allow the best ants through and avoid too much proliferation of forward ants in the network." – 2007 thesis, lines 4655-4659
So a1 < 1 is deliberate: a later ant must be strictly better than the generation's best by ~10% on both metrics to be forwarded, which is what makes the band a suppressor rather than an admitter. This is the same field and the same meaning as on main — only the default moves — so it is not the #173 "unit changed under the name" trap.
| double anthocnet::core::Config::antAcceptanceFactorNewHop = 2.0 |
Disjoint-path acceptance factor a2 — the less restrictive factor applied when a reactive forward ant's first hop (the node it travelled to immediately after the source) has not been seen among the ants this node already accepted for that (src, seqNum) generation:
"To boost the creation of disjoint paths, a different mechanism is applied, which takes into account the first hop taken by each ant. If this first hop is different from those taken by previously accepted ants, we apply a higher (less restrictive) acceptance factor a2 than in the case the first hop was already seen before (a2 was set to 2)." – 2007 thesis, lines 4667-4671
A new first hop is evidence that the ant arrived over a genuinely disjoint branch of the network, which is worth a path even when its metrics are worse than the incumbent's; a repeat first hop is a likely near-copy of a path already laid, so it must clear antAcceptanceFactor (a1). Used only when enableMultipath is on. Set below a1 and this mechanism inverts — it would penalise disjointness — so keep a2 >= a1.
New field, deliberately not folded into antAcceptanceFactor: silently redefining an existing field's meaning is the #173 defect this repo has already paid for once (see docs/configuration.md §2).
| int anthocnet::core::Config::proactiveMaxBroadcasts = 2 |
Max times a proactive forward ant may be (re)broadcast — covering both the per-hop exploratory broadcast ([1] §3.3) and a route gap en route.
Proactive ants monitor known paths; an unbounded budget let them flood any region of missing routes, amplifying route churn into control storms (issue #45).
| double anthocnet::core::Config::repairWaitFactor = 5.0 |
Local repair wait ([1] §3.5): after launching a repair ant, wait repairWaitFactor × the estimated end-to-end delay of the lost path for a backward repair ant; if none arrives, discard the buffered packets for that destination and send a link-failure notification (spec D6).
The paper sets the factor empirically to 5.
| double anthocnet::core::Config::repairTimeout = 1.0 |
| int anthocnet::core::Config::networkDiameter = 30 |
| std::size_t anthocnet::core::Config::maxPathLength = 100 |
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