fix(shelly-manager): disable TCP black-hole detection in the pod netns #1550

Merged

k.renner merged 1 commits from shelly-manager-no-mtu-probing into main

2026-11-02 09:37:09 +00:00

Author	SHA1	Message	Date
claude-botandClaude Opus 5.5	c68b9ad7c2	fix(shelly-manager): disable TCP black-hole detection in the pod netns ci/woodpecker/pr/ci-manifests-test Pipeline was successful Details ci/woodpecker/pr/ci-scripts-test Pipeline was successful Details Cilium sets net.ipv4.tcp_mtu_probing=1 in every pod netns (packetization-layer-pmtud-mode: blackhole). Shelly devices stop ACKing for seconds while they write flash during an OTA; after tcp_retries1 timeouts the kernel treats that as a PMTU black hole and halves the MSS on every stall, from 1440 down to the 48-byte floor. Upward probes need an open congestion state with cwnd >= 11, which the stalling device never allows, so the download stays at 48-byte segments and fills the device's receive buffer. The tuning plugin of the IoT attachment sets the sysctl to 0 for the pod netns; the annotation bump rolls the pod so the attachment is re-run. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_0185Qb5YG28FfnVi1ujMEV5C	2026-11-02 10:36:01 +01:00

Author

SHA1

Message

Date

claude-botandClaude Opus 5.5

c68b9ad7c2

fix(shelly-manager): disable TCP black-hole detection in the pod netns

ci/woodpecker/pr/ci-manifests-test Pipeline was successful

Details

ci/woodpecker/pr/ci-scripts-test Pipeline was successful

Details

Cilium sets net.ipv4.tcp_mtu_probing=1 in every pod netns
(packetization-layer-pmtud-mode: blackhole). Shelly devices stop ACKing
for seconds while they write flash during an OTA; after tcp_retries1
timeouts the kernel treats that as a PMTU black hole and halves the MSS
on every stall, from 1440 down to the 48-byte floor. Upward probes need
an open congestion state with cwnd >= 11, which the stalling device
never allows, so the download stays at 48-byte segments and fills the
device's receive buffer.

The tuning plugin of the IoT attachment sets the sysctl to 0 for the pod
netns; the annotation bump rolls the pod so the attachment is re-run.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0185Qb5YG28FfnVi1ujMEV5C

2026-11-02 10:36:01 +01:00