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Diffstat (limited to 'Documentation/networking/ip-sysctl.rst')
| -rw-r--r-- | Documentation/networking/ip-sysctl.rst | 25 |
1 files changed, 19 insertions, 6 deletions
diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index 363b4950d542..0f1251cce314 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -37,8 +37,8 @@ ip_no_pmtu_disc - INTEGER Mode 3 is a hardened pmtu discover mode. The kernel will only accept fragmentation-needed errors if the underlying protocol can verify them besides a plain socket lookup. Current - protocols for which pmtu events will be honored are TCP, SCTP - and DCCP as they verify e.g. the sequence number or the + protocols for which pmtu events will be honored are TCP and + SCTP as they verify e.g. the sequence number or the association. This mode should not be enabled globally but is only intended to secure e.g. name servers in namespaces where TCP path mtu must still work but path MTU information of other @@ -705,6 +705,8 @@ tcp_retries2 - INTEGER seconds and is a lower bound for the effective timeout. TCP will effectively time out at the first RTO which exceeds the hypothetical timeout. + If tcp_rto_max_ms is decreased, it is recommended to also + change tcp_retries2. RFC 1122 recommends at least 100 seconds for the timeout, which corresponds to a value of at least 8. @@ -733,7 +735,7 @@ tcp_rmem - vector of 3 INTEGERs: min, default, max net.core.rmem_max. Calling setsockopt() with SO_RCVBUF disables automatic tuning of that socket's receive buffer size, in which case this value is ignored. - Default: between 131072 and 6MB, depending on RAM size. + Default: between 131072 and 32MB, depending on RAM size. tcp_sack - BOOLEAN Enable select acknowledgments (SACKS). @@ -1097,7 +1099,7 @@ tcp_limit_output_bytes - INTEGER limits the number of bytes on qdisc or device to reduce artificial RTT/cwnd and reduce bufferbloat. - Default: 1048576 (16 * 65536) + Default: 4194304 (4 MB) tcp_challenge_ack_limit - INTEGER Limits number of Challenge ACK sent per second, as recommended @@ -1227,8 +1229,8 @@ tcp_pingpong_thresh - INTEGER tcp_rto_min_us - INTEGER Minimal TCP retransmission timeout (in microseconds). Note that the rto_min route option has the highest precedence for configuring this - setting, followed by the TCP_BPF_RTO_MIN socket option, followed by - this tcp_rto_min_us sysctl. + setting, followed by the TCP_BPF_RTO_MIN and TCP_RTO_MIN_US socket + options, followed by this tcp_rto_min_us sysctl. The recommended practice is to use a value less or equal to 200000 microseconds. @@ -1237,6 +1239,17 @@ tcp_rto_min_us - INTEGER Default: 200000 +tcp_rto_max_ms - INTEGER + Maximal TCP retransmission timeout (in ms). + Note that TCP_RTO_MAX_MS socket option has higher precedence. + + When changing tcp_rto_max_ms, it is important to understand + that tcp_retries2 might need a change. + + Possible Values: 1000 - 120,000 + + Default: 120,000 + UDP variables ============= |