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RFC: 64-Bit Sequence Numbers for TCP

This draft updates RFC 793 to allow the optional use of 64-bit sequence numbers. It also updates other standards to support the extended sequence number space.

Additionally, when you are re-using sequence number space in such a short timeframe, it is unclear that the existing mechanisms for detecting duplicate packets will be sufficient. This document proposes a mechanism for providing backwards compatibility with existing TCP implementations that only support 32-bit sequence numbers. When the client receives the initial reply (that is, a segment with both the SYN and ACK flags set), it checks for a valid 64-bit Sequence Number Option.

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