diff options
| author | Michael Tuexen <tuexen@FreeBSD.org> | 2020-03-31 15:54:54 +0000 |
|---|---|---|
| committer | Michael Tuexen <tuexen@FreeBSD.org> | 2020-03-31 15:54:54 +0000 |
| commit | 413c3db10102c265d9225f1f1610b37bb238d50a (patch) | |
| tree | f3656d26f4f38a79f8f49acf55abfca74ef88b5f /share | |
| parent | 11c7efe3a422cd7029326bddf7f2a1c6870a99fe (diff) | |
| download | src-413c3db10102c265d9225f1f1610b37bb238d50a.tar.gz src-413c3db10102c265d9225f1f1610b37bb238d50a.zip | |
Allow the TCP backhole detection to be disabled at all, enabled only
for IPv4, enabled only for IPv6, and enabled for IPv4 and IPv6.
The current blackhole detection might classify a temporary outage as
an MTU issue and reduces permanently the MSS. Since the consequences of
such a reduction due to a misclassification are much more drastically
for IPv4 than for IPv6, allow the administrator to enable it for IPv6 only.
Reviewed by: bcr@ (man page), Richard Scheffenegger
Sponsored by: Netflix, Inc.
Differential Revision: https://reviews.freebsd.org/D24219
Notes
Notes:
svn path=/head/; revision=359487
Diffstat (limited to 'share')
| -rw-r--r-- | share/man/man4/tcp.4 | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/share/man/man4/tcp.4 b/share/man/man4/tcp.4 index b6110068171c..0e35820c77d5 100644 --- a/share/man/man4/tcp.4 +++ b/share/man/man4/tcp.4 @@ -34,7 +34,7 @@ .\" From: @(#)tcp.4 8.1 (Berkeley) 6/5/93 .\" $FreeBSD$ .\" -.Dd March 29, 2020 +.Dd March 31, 2020 .Dt TCP 4 .Os .Sh NAME @@ -628,21 +628,31 @@ specific connection. This is needed to help with connection establishment when a broken firewall is in the network path. .It Va pmtud_blackhole_detection -Turn on automatic path MTU blackhole detection. -In case of retransmits OS will -lower the MSS to check if it's MTU problem. -If current MSS is greater than -configured value to try +Enable automatic path MTU blackhole detection. +In case of retransmits of MSS sized segments, +the OS will lower the MSS to check if it's an MTU problem. +If the current MSS is greater than the configured value to try .Po Va net.inet.tcp.pmtud_blackhole_mss and .Va net.inet.tcp.v6pmtud_blackhole_mss .Pc , it will be set to this value, otherwise, -MSS will be set to default values +the MSS will be set to the default values .Po Va net.inet.tcp.mssdflt and .Va net.inet.tcp.v6mssdflt .Pc . +Settings: +.Bl -tag -compact +.It 0 +Disable path MTU blackhole detection. +.It 1 +Enable path MTU blackhole detection for IPv4 and IPv6. +.It 2 +Enable path MTU blackhole detection only for IPv4. +.It 3 +Enable path MTU blackhole detection only for IPv6. +.El .It Va pmtud_blackhole_mss MSS to try for IPv4 if PMTU blackhole detection is turned on. .It Va v6pmtud_blackhole_mss |