feat(esw): wire peer anchors straight into the switch bridge

The Ethernet switch's kernel fast path: instead of a link crossing the
switch's per-port uBridge relay, the switch absorbs the peer's anchor into
its own kernel bridge. The peer's interface (Docker veth host end, QEMU
TAP, IOU port TAP, Dynamips port TAP) becomes the switch port, and frames
cross anchor -> switch bridge -> switch ports entirely in the kernel.

Wire format: the switch end receives nio_anchor ('join this interface to
my own bridge' — the mirror of nio_bridge), the peer end nio_bridge with a
null bridge ('your anchor is bridged elsewhere': carrier, markers and
impairments only — never bridge membership, and never a bridge delete, on
an interface this node does not own). Anchor names come from the shared
naming contract (utils.kernel_anchor), a pure function of node type, id,
adapter and port — the controller computes the peer's anchor while the
node may be stopped, which is what makes links to stopped nodes wireable.

Stopped peers defer the join; after any node of a link starts
(UDPLink.node_started) the controller re-pushes the switch NIO, and the
switch completes — or repairs, when a peer restart replaced its interface
under the same name — the join against the kernel's actual membership
instead of assuming it.

VLAN changes now edit membership in place: only the ports whose mode/VLAN
actually changed are touched, each losing exactly the previous mode's
entries the new mode does not want (the dot1q admits-all entry is one
range operation in both directions), and no port ever leaves the bridge to
change its VLANs. This replaces the old 'reset by re-enslaving' shortcut
(delif+addif on every wired port, added when the ports were the switch's
own TAPs): on absorbed anchors, re-enslaving an interface owned by another
node is where live testing watched links die — anchors occasionally lost
their bridge membership right after a ports_mapping update (later updates
then failed with delif EINVAL), reproducibly with qemu, IOU and Dynamips
peers and never with Docker's veths.

Eligibility: the switch side needs no capability of its own (its bridge
exists by construction); the peer must be able to anchor. Switch-to-switch
cascades stay on the relay — a kernel interface belongs to one bridge, and
joining two bridges needs a veth pair, deferred.

Verified live on a real server: qemu peers through four VLAN cycles with
both anchors enslaved throughout; a mixed switch (2 IOU + 2 Dynamips, four
kernel ports); Docker peers with real ICMP isolating and recovering (with
both anchors still enslaved); VPCS relay ports likewise in place.

gns3server/api/routes/compute/ethernet_switch_nodes.py

@@ -23,7 +23,7 @@ through uBridge's ``brctl`` module (see
 """
 
 import os
-from typing import Any
+from typing import Any, Union
 from uuid import UUID
 
 from fastapi import APIRouter, Body, Depends, HTTPException, Path, status
@@ -103,16 +103,20 @@ async def update_ethernet_switch(
     Update an Ethernet switch.
     """
 
-    data = jsonable_encoder(node_data, exclude_unset=True)
-    if "name" in data and node.name != data["name"]:
-        node.name = data["name"]
-    if "usage" in data:
-        node.usage = data["usage"]
-    if "ports_mapping" in data:
-        node.ports_mapping = data["ports_mapping"]
-        await node.update_port_settings()
-    if "console_type" in data:
-        node.console_type = data["console_type"]
+    node_data = jsonable_encoder(node_data, exclude_unset=True)
+    if "name" in node_data and node.name != node_data["name"]:
+        node.name = node_data["name"]
+    if "usage" in node_data:
+        node.usage = node_data["usage"]
+    if "ports_mapping" in node_data:
+        # capture the mapping before the setter replaces it: the VLAN
+        # reconcile diffs old against new to touch only what changed, in
+        # place (the setter itself keeps the port-count guard)
+        previous_mapping = [dict(port) for port in node.ports_mapping]
+        node.ports_mapping = node_data["ports_mapping"]
+        await node.update_port_settings(previous_mapping)
+    if "console_type" in node_data:
+        node.console_type = node_data["console_type"]
     node.updated()
     return node.asdict()
 
@@ -174,15 +178,20 @@ def reload_ethernet_switch(node: EthernetSwitch = Depends(dep_node)) -> None:
 @router.post(
     "/{node_id}/adapters/{adapter_number}/ports/{port_number}/nio",
     status_code=status.HTTP_201_CREATED,
-    response_model=schemas.UDPNIO,
+    response_model=Union[schemas.UDPNIO, schemas.AnchorNIO],
 )
 async def create_ethernet_switch_nio(
     *,
     adapter_number: int = Path(..., ge=0, le=0),
     port_number: int,
-    nio_data: schemas.UDPNIO,
+    nio_data: Union[schemas.UDPNIO, schemas.AnchorNIO],
     node: EthernetSwitch = Depends(dep_node),
-) -> schemas.UDPNIO:
+) -> Union[schemas.UDPNIO, schemas.AnchorNIO]:
+    """
+    Add a NIO (Network Input/Output) to the node: a UDP NIO wires the relay
+    datapath, an anchor NIO absorbs the peer's kernel anchor into this
+    switch's kernel bridge. The adapter number on the switch is always 0.
+    """
 
     nio = Builtin.instance().create_nio(jsonable_encoder(nio_data, exclude_unset=True))
     await node.add_nio(nio, port_number)
@@ -192,19 +201,21 @@ async def create_ethernet_switch_nio(
 @router.put(
     "/{node_id}/adapters/{adapter_number}/ports/{port_number}/nio",
     status_code=status.HTTP_201_CREATED,
-    response_model=schemas.UDPNIO,
+    response_model=Union[schemas.UDPNIO, schemas.AnchorNIO],
 )
 async def update_ethernet_switch_nio(
     *,
     adapter_number: int = Path(..., ge=0, le=0),
     port_number: int,
-    nio_data: schemas.UDPNIO,
+    nio_data: Union[schemas.UDPNIO, schemas.AnchorNIO],
     node: EthernetSwitch = Depends(dep_node),
-) -> schemas.UDPNIO:
+) -> Union[schemas.UDPNIO, schemas.AnchorNIO]:
     """
     Update a NIO (Network Input/Output) on the node: re-apply the packet
-    filters and traffic-insight markers carried by the NIO onto the port's
-    uBridge relay. The adapter number on the switch is always 0.
+    filters, traffic-insight markers and suspend state carried by the NIO —
+    on the port's uBridge relay for a relay port, on the absorbed anchor
+    (tc + kernel markers + carrier) for a kernel port. The adapter number
+    on the switch is always 0.
     """
 
     nio = node.get_nio(port_number)
@@ -212,6 +223,10 @@ async def update_ethernet_switch_nio(
     if nio_data.filters:
         nio.filters = nio_data.filters
     nio.markers = nio_data.markers or {}
+    # Suspend is what the compute turns into an admin-down anchor on a
+    # kernel link (native carrier), so it must reach the NIO like it does
+    # on the other node routes.
+    nio.suspend = getattr(nio_data, "suspend", None) or False
     await node.update_nio(port_number, nio)
     return nio.asdict()