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author | sbruno <sbruno@FreeBSD.org> | 2014-10-29 22:17:45 +0000 |
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committer | sbruno <sbruno@FreeBSD.org> | 2014-10-29 22:17:45 +0000 |
commit | 47c62aa0b0b32c345bff946b9d20c22176e209a6 (patch) | |
tree | 9dfed8b1a9ebe5ab0fd30460aa7b2f24a5340d19 /share | |
parent | 97d69448b874f5c698f9ee0ceddc195e496c8838 (diff) | |
download | FreeBSD-src-47c62aa0b0b32c345bff946b9d20c22176e209a6.zip FreeBSD-src-47c62aa0b0b32c345bff946b9d20c22176e209a6.tar.gz |
MFC r272720, 273061, 273062, 273063, 273064
Implement PLPMTUD blackhole detection (RFC 4821), inspired by code
from xnu sources. If we encounter a network where ICMP is blocked
the Needs Frag indicator may not propagate back to us. Attempt to
downshift the mss once to a preconfigured value.
Note, this is turned off by default.
Diffstat (limited to 'share')
-rw-r--r-- | share/man/man4/tcp.4 | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/share/man/man4/tcp.4 b/share/man/man4/tcp.4 index 1a44542..dd218bc 100644 --- a/share/man/man4/tcp.4 +++ b/share/man/man4/tcp.4 @@ -38,7 +38,7 @@ .\" From: @(#)tcp.4 8.1 (Berkeley) 6/5/93 .\" $FreeBSD$ .\" -.Dd November 8, 2013 +.Dd October 13, 2014 .Dt TCP 4 .Os .Sh NAME @@ -522,6 +522,21 @@ avoid packet drops. Number of retries (SYN or SYN/ACK retransmits) before disabling ECN on a 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 we will +lower the MSS to check if it's MTU problem. If current MSS is greater than +configured value to try, it will be set to it, otherwise, MSS will be set to +default values (net.inet.tcp.mssdflt and net.inet.tcp.v6mssdflt). +.It Va pmtud_blackhole_mss +MSS to try for IPv4 if PMTU blackhole detection is turned on. +.It Va v6pmtud_blackhole_mss +MSS to try for IPv6 if PMTU blackhole detection is turned on. +.It Va pmtud_blackhole_activated +Number of times the code was activated to attempt a MSS downshift. +.It Va pmtud_blackhole_min_activated +Number of times the blackhole MSS was used in an attempt to downshift. +.It Va pmtud_blackhole_failed +Number of times that we failed to connect after we downshifted the MSS. .El .Sh ERRORS A socket operation may fail with one of the following errors returned: |