From 3388bd9e9b82df6d7fe79fa4eee7c22a3277624e Mon Sep 17 00:00:00 2001 From: Dimitri Staessens Date: Tue, 21 Jul 2026 06:54:55 +0200 Subject: ipcpd: Add flow overshoot protection to mb-ecn The ECN marks were the only source of congestion information, and going into congestion collapse (dropping a lot of ECN packets and causing loss of signal) was unrecoverable. The sender's slow-start ramp clock now tracks a measured RTT to avoid overshooting into congestion collapse on the previously fixed (14ms) doubling on long-delay (e.g. 100ms) links. The flow allocator now carries a periodic heartbeat/ack to keep RTT estimates up-to-date. The heartbeat also serves as a congestion collapse detector: consecutive heartbeat losses will go into loss recovery, halving the window and pausing Additive Increase until the path is clear. The DT component now has a max_rtt config parameter that serves as a hint for the layer RTT to optimize slow-start for low-latency networks. These two mechanisms follow TCP, however only during slow start up to the first ECN signal and to recover from a total collapse until the ECN signal returns. MB-ECN is still fully RTT-independent in the AI/PD region. A shorter RTT path will just reach its equal fair share faster than a longer RTT path. Signed-off-by: Dimitri Staessens Signed-off-by: Sander Vrijders --- irmd.conf.in | 1 + 1 file changed, 1 insertion(+) (limited to 'irmd.conf.in') diff --git a/irmd.conf.in b/irmd.conf.in index b9b79782..02cb1da3 100644 --- a/irmd.conf.in +++ b/irmd.conf.in @@ -113,6 +113,7 @@ autobind=true # Defaults to false. # addr_size=4 # Defaults to 4 (32-bit addresses). # eid_size=8 # Defaults to 8 (64-bit endpoint IDs, only accepted option). # max_ttl=60 # Defaults to 60 (max 255). +# max_rtt=200 # Defaults to 200 (max 65535). # addr-auth="flat" # Defaults to flat (currently only option). # routing="lfa" # Defaults to link-state (options: link-state, lfa, ecmp). # ls_t_recalc=4 # Forwarding Function update interval (s) (Default 4). -- cgit v1.2.3