Merge pull request #2327 from quicwg/ianswett-ignore-loss

Ignore packet loss when the keys are not available

draft-ietf-quic-recovery.md

@@ -44,6 +44,23 @@ normative:
         org: Mozilla
         role: editor
 
+  QUIC-TLS:
+    title: "Using TLS to Secure QUIC"
+    date: {DATE}
+    seriesinfo:
+      Internet-Draft: draft-ietf-quic-tls-latest
+    author:
+      -
+        ins: M. Thomson
+        name: Martin Thomson
+        org: Mozilla
+        role: editor
+      -
+        ins: S. Turner
+        name: Sean Turner
+        org: sn3rd
+        role: editor
+
 informative:
 
   FACK:
@@ -434,14 +451,30 @@ packet is received.  The client MAY use this value to seed the RTT estimator for
 a subsequent connection attempt to the server.
 
 
-#### Discarding Initial State {#discard-initial}
+#### Discarding Keys and Packet State {#discarding-packets}
+
+When packet protection keys are discarded (see Section 4.9 of {{QUIC-TLS}}), all
+packets that were sent with those keys can no longer be acknowledged because
+their acknowledgements cannot be processed anymore. The sender considers them no
+longer in flight. That is, the sender SHOULD discard all recovery state
+associated with those packets and MUST remove them from the count of bytes in
+flight.
+
+Endpoints stop sending and receiving Initial packets once they start exchanging
+Handshake packets (see Section 17.2.2.1 of {{QUIC-TRANSPORT}}). At this point,
+recovery state for all in-flight Initial packets is discarded.
 
-As described in Section 17.5.1 of {{QUIC-TRANSPORT}}, endpoints stop sending and
-receiving Initial packets once they start exchanging Handshake packets.  At this
-point, all loss recovery state for the Initial packet number space is also
-discarded. Packets that are in flight for the packet number space are not
-declared as either acknowledged or lost.  After discarding state, new Initial
-packets will not be sent.
+When 0-RTT is rejected, recovery state for all in-flight 0-RTT packets is
+discarded.
+
+If a server accepts 0-RTT, but does not buffer 0-RTT packets that arrive
+before Initial packets, early 0-RTT packets will be declared lost, but that
+is expected to be infrequent.
+
+It is expected that keys are discarded after packets encrypted with them would
+be acknowledged or declared lost.  Initial secrets however might be destroyed
+sooner, as soon as handshake keys are available (see Section 4.10 of
+{{QUIC-TLS}}).
 
 
 ### Probe Timeout {#pto}
@@ -952,6 +985,14 @@ The recovery period limits congestion window reduction to once per round trip.
 During recovery, the congestion window remains unchanged irrespective of new
 losses or increases in the ECN-CE counter.
 
+## Ignoring Loss of Undecryptable Packets
+
+During the handshake, some packet protection keys might not be
+available when a packet arrives. In particular, Handshake and 0-RTT packets
+cannot be processed until the Initial packets arrive, and 1-RTT packets
+cannot be processed until the handshake completes.  Endpoints MAY
+ignore the loss of Handshake, 0-RTT, and 1-RTT packets that might arrive before
+the peer has packet protection keys to process those packets.
 
 ## Probe Timeout
 
@@ -1006,23 +1047,6 @@ paces the sending of any packets in excess of the initial congestion window.
 A sender MAY implement alternate mechanisms to update its congestion window
 after idle periods, such as those proposed for TCP in {{?RFC7661}}.
 
-## Discarding Packet Number Space State
-
-When keys for a packet number space are discarded, any in-flight packets
-sent with those keys are removed from the count of bytes in flight.  Loss
-recovery state is also discarded, so no loss events will occur for any
-in-flight packets from that space (see {{discard-initial}}).  Note that it is
-expected that keys are discarded after those packets would be declared lost,
-but Initial secrets are destroyed earlier.
-
-When 0-RTT is rejected, all in-flight 0-RTT packets are removed from
-the count of bytes in flight.  Loss recovery state is also discarded, so no
-loss events will occur for any in-flight 0-RTT packets.
-
-If a server accepts 0-RTT, but does not buffer 0-RTT packets that arrive
-before Initial packets, early 0-RTT packets will be declared lost, but that
-is expected to be infrequent.
-
 ## Pseudocode
 
 ### Constants of interest {#cc-consts-of-interest}