Currently, QUIC is only marked as broken when the QUIC handshake fails. However, this does not catch situations where the connection becomes a blackhole after the handshake. We have seen this behavior in the wild several times.
To handle this, we should also mark QUIC as broken if a connection times out with open streams or if it suffers too many RTOs.
Comment 1 by bugdroid1@chromium.org
, Apr 13 2017