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dcsctp: Increase RTO limits

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The previous limits were taken from Oracles SCTP stack[1] as they were
more up-to-date than the suggested ones in RFC4960. However, after
having evaluated them for a while, it's evident that they are a bit too
aggressive and likely have their origin from a wired LAN network.

Let's do a re-take. These values have been taken from Solaris TCP
stack[2]. They are even less aggressive than Linux defaults. This can be
iterated even more, and is always possible to override by the client.

It's generally the increase of rto_min that is helping here, as the
delayed SACK and RTT jitter require that the RTO.min is quite much
higher than the delayed SACK timeout of the peer (which isn't in control
by us, but one can assume it's 200ms or less). And with a too low
RTO.min, it's increased risk of getting spurious retransmissions and
decreasing the congestion window.

[1] https://docs.oracle.com/cd/E93309_01/docs.466/SIGTRAN/GUID-2136614F-4BED-407C-87B0-7EE10E0FF534.htm
[2] https://docs.oracle.com/cd/E19120-01/open.solaris/819-2724/chapter4-69/index.html

Bug: webrtc:12943
Change-Id: I9678ac4396286a55c251c5f57589379da70fd27d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/231139
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#34927}
This commit is contained in:
Victor Boivie
2021-09-03 14:15:02 +02:00
committed by WebRTC LUCI CQ
parent b02ed8f026
commit 2e78f09c1a
1 changed files with 3 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
net/dcsctp/public/dcsctp_options.h
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@ -92,17 +92,17 @@ struct DcSctpOptions {
// than this value, it will be discarded and not used for e.g. any RTO // than this value, it will be discarded and not used for e.g. any RTO
// calculation. The default value is an extreme maximum but can be adapted // calculation. The default value is an extreme maximum but can be adapted
// to better match the environment. // to better match the environment.
DurationMs rtt_max = DurationMs(8000); DurationMs rtt_max = DurationMs(60'000);
// Initial RTO value. // Initial RTO value.
DurationMs rto_initial = DurationMs(500); DurationMs rto_initial = DurationMs(500);
// Maximum RTO value. // Maximum RTO value.
DurationMs rto_max = DurationMs(800); DurationMs rto_max = DurationMs(60'000);
// Minimum RTO value. This must be larger than an expected peer delayed ack // Minimum RTO value. This must be larger than an expected peer delayed ack
// timeout. // timeout.
DurationMs rto_min = DurationMs(220); DurationMs rto_min = DurationMs(400);
// T1-init timeout. // T1-init timeout.
DurationMs t1_init_timeout = DurationMs(1000); DurationMs t1_init_timeout = DurationMs(1000);