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c343ce0b8f
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.
75 lines
2.3 KiB
Python
75 lines
2.3 KiB
Python
#
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# Copyright (C) 2026 GNS3 Technologies Inc.
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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"""
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Interface for kernel-datapath bridge NIOs.
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A NIO of this type instructs the node to enslave its adapter's veth host end
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into the named Linux kernel bridge instead of wiring a uBridge UDP relay.
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Frames then flow entirely in the kernel (veth -> bridge -> veth). Impairment
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filters ride the NIO and run as one tc netem qdisc per veth host end (the
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types without a netem equivalent — frequency_drop, bpf — stay relay-only);
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markers and packet capture are served by uBridge's AF_PACKET modules on the
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veth host end (marker add_kernel / capture start_kernel).
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``bridge`` may be ``None``: the anchor is then bridged elsewhere — an
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Ethernet switch absorbed it into the switch's own kernel bridge — and this
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node applies only the link state the anchor carries (carrier, markers,
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impairments), never bridge membership.
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"""
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from .nio import NIO
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class NIOBridge(NIO):
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"""
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Kernel-bridge NIO.
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:param bridge: name of the per-link Linux kernel bridge, or None when
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the anchor is bridged by an Ethernet switch (see module docstring)
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"""
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def __init__(self, bridge):
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super().__init__()
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self._bridge = bridge
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@property
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def bridge(self):
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"""
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Returns the kernel bridge name, or None for an externally bridged
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anchor.
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:returns: bridge name
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"""
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return self._bridge
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def __str__(self):
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return "NIO bridge"
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def asdict(self):
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return {
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"type": "nio_bridge",
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"bridge": self._bridge,
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"suspend": self._suspended,
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"filters": self._filters,
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"markers": self._markers,
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}
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