xquic — Path MTU black hole above a threshold

Pass

Recovered: the path swallowed 374 datagram(s) and the transfer completed without the detector naming a black hole; MTU settled at 1200, 0 probe(s) lost.

The client did what the clause requires.

What was measured

Client

xquic — Alibaba xquic + BoringSSL, 2060a44

Test

Path MTU black hole above a threshold — q-pmtu-blackhole

Clause

RFC 9000 §14, RFC 8899 (SHOULD)

Class

resilience — Recovered rather than giving up.

Required behaviour

Detect the black hole, probe down to a working size, and keep the connection. Path-MTU discovery is driven past the limit on this port, so it engages on every connection.

Measured

2026-09-18

Reproduce it

The suite is the judge, so the reproduction is to point the same client at the same test and let the server report what it saw.

SESSION=$(curl -sX POST https://conformance.pqcrypta.com/session | jq -r .id)
# then drive xquic at the test URL and read the verdict:
curl -s https://conformance.pqcrypta.com/report/$SESSION.json | jq '.results["q-pmtu-blackhole"]'