Initial public release — aci-sim v0.16.0

aci-sim is a stateful REST simulator of a 2-site Cisco ACI fabric
(per-site APIC + ND/NDO management planes) — for testing ACI automation
(Ansible cisco.aci / cisco.mso, aci-py, custom REST clients) and CI gates
without real hardware.

Highlights: APIC + NDO REST surface served from one in-memory MIT built
from a declarative topology.yaml; port mode + sandbox (real per-device IPs
on :443) run modes; LLDP/CDP neighbor visibility; NDO->APIC deploy mirror
(multi-site templates materialize onto the target sites' APIC stores);
real-APIC fvBD default attributes; file-backed state save/restore; an
`aci-sim` CLI (validate/show/graph/run/new/init/lldp); and an 888-test suite.

History squashed for the public release.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

aci_sim/build/underlay.py

@@ -0,0 +1,106 @@
+"""build/underlay.py — bgpInst (local ASN), isisAdjEp + ospfAdjEp.
+
+Intra-fabric underlay IGP is IS-IS: isisAdjEp is emitted between every directly
+cabled spine↔leaf pair. OSPF is used ONLY by spines toward the inter-site network
+(IPN/ISN) and ONLY in a multi-site fabric — leaves never peer OSPF with the ISN.
+bgpInst carries the site ASN and anchors all BGP peers (overlay.py adds children).
+
+Tier-3 (PR-20): ospfIf also carries `helloIntvl`/`deadIntvl`, fed by
+`isn.ospf_hello`/`isn.ospf_dead` (real ACI defaults 10/40) — previously not
+carried on this MO at all.
+"""
+from __future__ import annotations
+
+from aci_sim.mit.mo import MO
+from aci_sim.mit.store import MITStore
+from aci_sim.topology.schema import Site, Topology
+from aci_sim.build.fabric import loopback_ip
+from aci_sim.build.cabling import cabling_links
+
+
+def build(topo: Topology, site: Site, store: MITStore) -> None:
+    """Emit bgpInst per node + OSPF/IS-IS adjacencies along fabric links."""
+    pod = site.pod
+    spine_ids = {n.id for n in site.spine_nodes()}
+
+    # bgpInst per node — carries the site ASN; overlay.py adds bgpPeer children
+    for node in site.all_nodes():
+        store.add(MO(
+            "bgpInst",
+            dn=f"topology/pod-{pod}/node-{node.id}/sys/bgp/inst",
+            asn=str(site.asn),
+        ))
+
+    # isisDom per node (IS-IS is the ACI underlay IGP)
+    for node in site.all_nodes():
+        store.add(MO(
+            "isisDom",
+            dn=f"topology/pod-{pod}/node-{node.id}/sys/isis/inst-default/dom-overlay-1",
+            name="overlay-1",
+            operSt="up",
+        ))
+
+    # IS-IS adjacencies — the intra-fabric underlay, between directly-cabled
+    # spine↔leaf pairs only. Convention: n1=spine, n2=leaf (same as cabling.py).
+    for n1, s1, p1, n2, s2, p2 in cabling_links(site):
+        spine_id, leaf_id = (n1, n2) if n1 in spine_ids else (n2, n1)
+        spine_port = f"eth{s1}/{p1}" if n1 in spine_ids else f"eth{s2}/{p2}"
+        leaf_port  = f"eth{s2}/{p2}" if n1 in spine_ids else f"eth{s1}/{p1}"
+        spine_lb = loopback_ip(pod, spine_id)
+        leaf_lb  = loopback_ip(pod, leaf_id)
+
+        spine_isis_base = f"topology/pod-{pod}/node-{spine_id}/sys/isis/inst-default/dom-overlay-1"
+        store.add(MO(
+            "isisAdjEp",
+            dn=f"{spine_isis_base}/if-[{spine_port}]/adj-[{leaf_lb}]",
+            operSt="up", sysId=leaf_lb, lastTrans="00:00:00", numAdjTrans="1",
+        ))
+        leaf_isis_base = f"topology/pod-{pod}/node-{leaf_id}/sys/isis/inst-default/dom-overlay-1"
+        store.add(MO(
+            "isisAdjEp",
+            dn=f"{leaf_isis_base}/if-[{leaf_port}]/adj-[{spine_lb}]",
+            operSt="up", sysId=spine_lb, lastTrans="00:00:00", numAdjTrans="1",
+        ))
+
+    # OSPF adjacencies — ONLY spine↔IPN/ISN, and ONLY in a multi-site fabric.
+    # Leaves never run OSPF to the ISN. One adjacency per spine toward the IPN,
+    # on eth1/{49+si} — interfaces.py builds a matching dedicated ISN uplink
+    # l1PhysIf on each spine (multi-site only) at that exact port, so this
+    # ospfAdjEp interface always resolves against a real port inventory entry.
+    # autoACI reads: iface = dn.split("/if-[")[1]; neighbor = peerIp or nbrId.
+    if len(topo.sites) > 1:
+        ipn_ip = f"172.16.{site.id}.254"  # the IPN/ISN router this site's spines peer with
+        # Tier-2 (PR-19): isn.ospf_area feeds ospfIf.area/ospfAdjEp.area — was
+        # a hardcoded "0.0.0.0" literal; a topology author overriding
+        # isn.ospf_area now sees it reflected in the actual OSPF object
+        # instead of a value the schema stored but no builder honored.
+        ospf_area = topo.isn.ospf_area
+        # Tier-3 (PR-20): isn.ospf_hello/ospf_dead (real ACI defaults 10/40)
+        # feed ospfIf.helloIntvl/deadIntvl — previously not carried on this
+        # MO at all.
+        ospf_hello = str(topo.isn.ospf_hello)
+        ospf_dead = str(topo.isn.ospf_dead)
+        for si, spine in enumerate(site.spine_nodes()):
+            ospf_base = f"topology/pod-{pod}/node-{spine.id}/sys/ospf/inst-default/dom-overlay-1"
+            store.add(MO("ospfDom", dn=ospf_base, name="overlay-1", operSt="up"))
+            # Batch-1: ospfIf nested between ospfDom and ospfAdjEp — same
+            # eth1/{49+si} ISN uplink port interfaces.py already builds a
+            # dedicated l1PhysIf for, so the existing ospfAdjEp below sits on
+            # a real, matching ospfIf (consumer: autoACI's fabric_ospf.py,
+            # which reads ospfIf.id (falling back to ifId) + area + operSt).
+            if_port = f"eth1/{49 + si}"
+            if_dn = f"{ospf_base}/if-[{if_port}]"
+            store.add(MO(
+                "ospfIf",
+                dn=if_dn,
+                id=if_port,
+                area=ospf_area,
+                operSt="up",
+                helloIntvl=ospf_hello,
+                deadIntvl=ospf_dead,
+            ))
+            store.add(MO(
+                "ospfAdjEp",
+                dn=f"{if_dn}/adj-[{ipn_ip}]",
+                operSt="full", peerIp=ipn_ip, nbrId=ipn_ip, area=ospf_area,
+            ))