Re: [quicwg/base-drafts] Fix handling of Retry in recovery (#3148)

ianswett <notifications@github.com> Thu, 24 October 2019 13:56 UTC

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Subject: Re: [quicwg/base-drafts] Fix handling of Retry in recovery (#3148)
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ianswett approved this pull request.

Thanks, nice update!

> -
-A Retry or Version Negotiation packet causes a client to send another Initial
-packet, effectively restarting the connection process and resetting congestion
-control and loss recovery state, including resetting any pending timers.  Either
-packet indicates that the Initial was received but not processed.  Neither
-packet can be treated as an acknowledgment for the Initial.
-
-The client MAY however compute an RTT estimate to the server as the time period
-from when the first Initial was sent to when a Retry or a Version Negotiation
-packet is received.  The client MAY use this value to seed the RTT estimator for
-a subsequent connection attempt to the server.
+## Handling Retry Packets
+
+A Retry packet causes a client to send another Initial packet, effectively
+restarting the connection process.  A Retry packet indicates that the Initial
+was received, but not processed.  A Retry packet cannot be treated as an

```suggestion
was received, but not processed.  A Retry packet MUST NOT be treated as an
```

> +## Handling Retry Packets
+
+A Retry packet causes a client to send another Initial packet, effectively
+restarting the connection process.  A Retry packet indicates that the Initial
+was received, but not processed.  A Retry packet cannot be treated as an
+acknowledgment.
+
+Clients that receive a Retry packet reset congestion control and loss recovery
+state, including resetting any pending timers.  Other connection state, in
+particular cryptographic handshake messages, is retained; see Section 17.2.5 of
+{{QUIC-TRANSPORT}}.
+
+The client MAY compute an RTT estimate to the server as the time period from
+when the first Initial was sent to when a Retry or a Version Negotiation packet
+is received.  The client MAY use this value in place of its default for the
+initial RTT estimate.

Given how IP routing works, accomplishing what you're suggesting would be quite difficult, but I agree there are cases this isn't perfect.  But it's typically better than any other available value, including the 1 second default.

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