Stall case: server response exceeds the 3600-byte budget
Server
Client
ClientHello
1200 bytes (padded)
ServerHello + part of Cert
ServerHello + Cert exceeds 3600 bytes — budget exhausted
server
stalled
⏸
+1 RTT
wasted
Handshake-protected packet
client has handshake keys after ServerHello
address validated
3x cap lifted
rest of Cert, CertVerify, Finished
free to send, no cap
client Finished + 1-RTT request
handshake complete
1-RTT response (application data)
client finally has the data