Open
Conversation
The dcSCTP receiver was advertising available window space (arwnd) based solely on payload bytes, while the sender's rwnd estimation included packet headers. This mismatch caused the sender to underestimate the receiver's available buffer, potentially leading to reduced throughput. This commit resolves the issue by ensuring both sender and receiver use payload bytes, as headers have been removed on the receiver side while in the reassembly queue. This is a Rust port of the fix to the upstream C++ implementation at https://webrtc-review.googlesource.com/c/src/+/377122.
lndmrk
reviewed
Mar 13, 2026
| // and by the number of bytes of duplicated chunks reported in Duplicate TSNs. | ||
| let old_pba = self.partial_bytes_acked; | ||
| self.partial_bytes_acked += total_bytes_acked; | ||
| self.partial_bytes_acked += total_payload_bytes_acked; |
Collaborator
There was a problem hiding this comment.
Wait, shouldn't this include header and padding?
https://datatracker.ietf.org/doc/html/rfc9260#section-7.2.2-4.2.1
Collaborator
There was a problem hiding this comment.
Hmm, I guess it only SHOULD?
| if !self.t3_rtx.is_running() { | ||
| self.t3_rtx.start(now); | ||
| } | ||
| let sent_bytes: usize = to_be_sent |
Collaborator
There was a problem hiding this comment.
Drive-by comment: Looks like this just duplicated bytes_retransmitted previosly.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The dcSCTP receiver was advertising available window space (arwnd) based solely on payload bytes, while the sender's rwnd estimation included packet headers. This mismatch caused the sender to underestimate the receiver's available buffer, potentially leading to reduced throughput.
This commit resolves the issue by ensuring both sender and receiver use payload bytes, as headers have been removed on the receiver side while in the reassembly queue.
This is a Rust port of the fix to the upstream C++ implementation at https://webrtc-review.googlesource.com/c/src/+/377122.