microsoft / microsoft/demikernel

[inetstack] Add Optional TCP Feature - SACK (Selective Acknowledgement)

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enhancement
Dominant language
Rust
Stars
1.2k
Forks
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PR merge metrics
No merged PRs in 30d

Description

TCP has an optional feature called Selective Acknowledgement (SACK) which allows a receiver to acknowledge chunks of data, rather than just a single cumulative value. In certain situations, this can save a sender from a large number of needless retransmissions.

This feature is especially useful on somewhat lossy long (high RTT) fat (high bandwidth) networks. Since data centers tend to have low loss, short fat networks, this may not be a high priority for us if we are primarily targeting data center deployments.

See RFC 2018 and RFC 2883 for complete description of SACK. Also see RFC 6675 for a SACK-based loss recovery algorithm.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with RFC 2018 and RFC 2883 for SACK semantics, then inspect the inetstack TCP implementation and its loss-recovery path. RFC 6675 describes the related recovery algorithm. Done means SACK is supported for acknowledging received chunks and integrated with TCP loss recovery.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
networking
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
25/100

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