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Add network related comments into the release notes

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Updating the release notes with some of the highlights - especially where
the default behavior now changed (PRR for improved SACK loss recovery).
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Richard Scheffenegger 2021-02-12 12:16:37 +01:00
parent 24692b4a7f
commit ffec1b2d34
1 changed files with 14 additions and 0 deletions

14
website/content/en/releases/13.0R/relnotes.adoc
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@ -175,6 +175,8 @@ This section covers changes and additions to devices and device drivers since {r
This section covers changes and additions to file systems and other storage subsystems, both local and networked.
For {{< manpage "iscsi" "4" >}} and {{< manpage "ctld" "8" >}}, support for specifying network QoS in the form of DiffServ Codepoints (DSCP) and Ethernet Priority Code Point (PCP) was added. {{< commit "ddf1072aac49" >}} {{< sponsored "NetApp" >}}
[[storage-general]]
=== General Storage
@ -193,6 +195,18 @@ This section covers the boot loader, boot menu, and other boot-related changes.
This section describes changes that affect networking in FreeBSD.
For {{< manpage "tcp" "4">}}, Proportional Rate Reduction, as described by RFC6937, to improve SACK loss recovery during burst loss and ACK thinning scenarios, was implemented and is enabled by default.
A new {{< manpage "sysctl" "8" >}} has been added, `net.inet.tcp.do_prr`, which when set to `0` will restore the prior behavior.
It is expected that PRR generally helps improve loss recovery performance and prevent numerous preventable RTO stalls.
This surpasses the prior behavior, but a strictly packet conserving variant can be enabled.
When misconfigured token bucket traffic policer can cause persistent loss even during loss recovery, activating the conservative PRR variant may prevent some retransmission timeouts (RTO) and associated session stalls for a few milliseconds while behaving less optimal in the general case.
For this, a new {{< manpage "sysctl" "8">}} was added, `net.inet.tcp.do_prr_conservative`.
Setting this variable to `1` will enable strictly packet conserving behavior (at most 1 segment for each ACK received), while the normal variant may send up to 2 segments per received ACK - helping in cases of ACK thinning or significant burst loss events. {{< commit "0e1d7c25c5ab" >}} {{< sponsored "NetApp" >}}
The {{< manpage "cc_cubic" "4">}} has been improved to address various corner cases and align more closely with the standard in RFC8312. {{< commit "40f9078ff9d9" >}} {{< sponsored "NetApp" >}}
The {{< manpage "ping" "8" >}} and {{< manpage "ping6" "8" >}} utilities both support setting network QoS, with IP DSCP {{< commit "6034024daddb" >}} and Ethernet PCP {{< commit "81a6f4c7ae69" >}} {{< sponsored "NetApp" >}}
[[network-general]]
=== General Network