ouroboros/src/ipcpd/unicast/ca/nop.h, branch 0.24.0Ouroboros main repositoryhttps://ouroboros.rocks/cgit/ouroboros/atom?h=0.24.02026-07-19T09:44:36+00:00ipcpd: Rework congestion avoidance2026-07-19T09:44:36+00:00Dimitri Staessensdimitri@ouroboros.rocks2026-07-05T16:58:37+00:00urn:sha1:d050aea4cd892d71ed7fc78b6c6149a7231db5fc
Congestion avoidance is a property of the layer, orthogonal to ARQ
and to flow control: FRCP retransmits and lets the peer pace the
sender, per flow, end-to-end; the IPCP paces path aggregates. Each
signal means one thing: a loss triggers a retransmission, a mark
means congestion, the peer window means a slow receiver. Every flow
is paced by the same rate law whatever its QoS, so a greedy raw
sender shares a bottleneck fairly with a reliable stream.
The unit of control is the (destination address, QoS cube)
aggregate: all flows toward that destination share one controller
and one rate; a start-time fair-queuing pacer divides the rate
across them by deadline instead of blocking the send path, and a
new flow rides the aggregate's estimates at its current rate, with
no probing of its own. Slow start runs once per aggregate.
The congestion signal is a multi-bit magnitude: forwarders mark
packets with their standing queue depth, MAX-combined across hops,
so a packet carries the deepest queue on its path. The receiver
feeds back a time-integral mean over a window that adapts to the
flow's byte rate, measuring a slow flow with the same fidelity as a
fast one. The sender runs AIMD scaled by elapsed wall-clock time,
which makes the steady-state allocation RTT-independent.
The PCI gains one byte: the path capacity as a quarter-log2 code.
Forwarders estimate their egress rate from busy-period drain and
MIN-stamp the byte, the receiver returns the window minimum with
its feedback, and the sender scales its rate floor and additive
slope to the bottleneck (C / 32). A deep cut implies a backlogged
bottleneck and a backlogged bottleneck advertises its capacity, so
the scaled floor is live exactly when recovery needs it: the probe
heals a halving in seconds at any link rate, and the floor bounds
the deepest hole to a factor 32 below the bottleneck.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
build: Update copyright to 20262026-02-18T06:54:56+00:00Dimitri Staessensdimitri@ouroboros.rocks2026-02-15T09:21:02+00:00urn:sha1:0d72b59c2964208ea34ce2322978344d7ff1a223
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
build: Update licenses to 20242024-01-13T09:20:14+00:00Dimitri Staessensdimitri@ouroboros.rocks2024-01-05T08:07:30+00:00urn:sha1:8742a31bf672c5bc087601ec39ab1feb206d2446
Slow but steady.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
build: Update copyright to 20232023-02-13T20:10:10+00:00Dimitri Staessensdimitri@ouroboros.rocks2023-02-09T16:38:30+00:00urn:sha1:c3814fa77eb7afbe6e798ded0fdff2df74ad8642
2022 was a rather slow year...
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
build: Update copyright to 20222022-04-03T16:01:02+00:00Dimitri Staessensdimitri@ouroboros.rocks2022-04-02T08:44:18+00:00urn:sha1:9639e28fd2dfdb4c2c1fb544b07f2ab6a0395934
Growing pains.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
ipcpd: Restructure policy code2021-12-06T16:52:08+00:00Dimitri Staessensdimitri@ouroboros.rocks2021-12-04T14:35:36+00:00urn:sha1:11d2ecc140486949c8d81e984137263ca48d5799
The policies were all in a single folder pol/, and have been moved to
a folder per component/mechanism to keep things a bit more orderly.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>