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.
Replace psutil.net_if_addrs() scan with a deterministic name derived from
the switch's node UUID: gns3 + first 6 hex chars (10 chars, fits kernel
IFNAMSIZ limit of 15). Taps: <bridge>-<port> (12-13 chars).
Crash recovery: brctl delete the bridge first (best-effort), then create
fresh. Stale bridges from abnormal gns3server shutdown are automatically
reclaimed on the next start — no EEXIST or leaked interfaces.
Remove _free_iface helper and psutil import (no longer needed).
brctl create leaves the bridge administratively DOWN. Add link set up
so the bridge actually forwards frames between enslaved ports.
Also record Docker iptables FORWARD DROP pitfall in project memory.
Replace the builtin EthernetSwitch stub with a Linux kernel bridge backed
by uBridge's brctl module. Each switch node creates one kernel bridge
(gns3br{N}) with VLAN filtering; each port is a persistent TAP enslaved to
the bridge, relayed by a per-port uBridge bridge (nio_tap <-> nio_udp).
- Access/dot1q/qinq port modes translated to brctl vlan primitives
- Compute router repointed from Dynamips to Builtin manager
- Tests updated: 21 router-level tests + 215 surrounding tests pass
- Real-kernel e2e verified: access 100 PVID untagged, dot1q trunk
VIDs 1-4094 + native 1, qinq 802.1ad proto + 200 PVID
Ethertype 0x9100/0x9200 handling and port-count guard relaxation are
deferred pending resolution.
