RFC 9000 / MECHANISMS

Recover data, not packets

Lost information can be carried again in new frames and new packets. A sent packet number is never reused in its number space.

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DIAGRAM§ 13.3 ↗

RFC 9000 · § 13.3EXAMPLE

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Repackage the missing information.

The same stream offset can appear in a later packet with a new packet number.

Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references

KEY POINT

A retransmission gets a new packet identity.

ACK frames describe received packet-number ranges in their own packet-number space.
QUIC does not retransmit a lost packet whole; it determines what information still needs delivery.
Initial, Handshake, and Application Data use separate packet-number spaces.

DETAILS

RFC 9002 defines loss detection and congestion response. FIN ends a stream; CONNECTION_CLOSE ends the connection, with closing and draining behavior in § 10.

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